Date   

IC-7300 composite noise

Conrad, PA5Y
 

The Keysite picture was showing the spurs from a Hermes at 28.4 MHz with a 192kHz sample rate using the V1 firmware. it has nothing to do with the IC7300.

 

I have spare time now so I will repost the image of the IC-7300.

 

IC-7300 is at 30W output on 28.2 MHz with offsets from 10Hz to 1MHz, Blue trace is PN, Black trace is AM noise, Green trace is composite noise. This uses the FSWP which can measure AM noise and PN simultaneously.

 

Then I will go away for a while.

 

 

 

 

From: main@SDR-Radio.groups.io <main@SDR-Radio.groups.io> On Behalf Of jdow via groups.io
Sent: 25 February 2022 14:39
To: main@SDR-Radio.groups.io
Subject: Re: [SDR-Radio] Open HPSDR Hermes (14 bit ADC, EP3C25) Transceiver Card

 

Looking at the Keysight picture you posted it's hard to tell the characteristics of the peaks that appear beside the (was it?) 28.4 MHz signal. (The screen notation of 390 kHz is confusing. That is the marker's offset?)

It appears like the 7300 is using a digital frequency synthesizer with way too few bits to make a good signal. If I got a rig that bad I think I'd have some stern words with ICOM about it. While it might be marginally legal it is unethical to sell something that bad. (And at 100W I thought the limit was -70 dB in the US.

{^_^}

On 20220225 04:03:42, Conrad, PA5Y wrote:

Hi, no it is actually 5 different IC7300s tested by 3 different people, including Rob Sherwood. if you have time you can see the plots and some other data that I posted earlier just do a search. I’m in my lunch break or I would do it for you.

 

Yes my TX IS that good but it is easier for me because I use 0dBm transverter drives at 28Mhz and transverters with high quality Xtal local oscillators. The 0dBm from either my K3S or TS-890S is very good indeed. IMD3 from both is better than -50dBc.

 

On 144 MHz,  PN noise at 1kHz separation is -144dBc/Hz and close to 156dBc/Hz at 10kHz. This is with the LO PLL active, free running it is a little better. Composite noise is the same as in this case it is PN dominated. IM3 is -38dBc but more importantly the 7th and 9th orders are better than -80dBc. This is achieved by using tetrode finals on all bands.

 

432 and 1296 are of course worse as the LOs are multiplied from Xtals in the VHF region. However my TX is some 40dB better than an IC-9700 at 1.3GHz at 10kHz separation.

 

 

Only 50MHz is a little worse due to my TS-890S PA linearity but with the noise on 6m being higher it is acceptable. When I am on FT8 where linearity does not matter it is superb. But who cares we are all on the same ‘channel’.

 

73

 

Conrad PA5Y

 

From: main@SDR-Radio.groups.io <main@SDR-Radio.groups.io> On Behalf Of jdow via groups.io
Sent: 25 February 2022 11:49
To: main@SDR-Radio.groups.io
Subject: Re: [SDR-Radio] Open HPSDR Hermes (14 bit ADC, EP3C25) Transceiver Card

 

I suspect your specification is still beyond the state of the art. Is your transmitter that good?

It sounds like the 7300 is cleaner than average close in but has some issues fairly far out. That is a little surprising. I wonder if the "IP+" technology is simply RF feedback to linearize the transmitter stages such as is seen in the old Collins kW SSB amplifiers. I can see that having an issue that depends on the charteristics of the feedback loop. But those are strange characteristics.

I take it the noise peaks are broadband, right? Do they depend on the transmit frequency in any way? It sounds very much like there is a defect in a specific radio near you. Is that the case or are hams measuring this in general? If this affects all the 7300s then the FPGA code will probably have to be reworked to fix the bug. I kinda wish I had one and a nice lab with lots of pertinent test equipment. I doubt Keysight and ICOM would set me up to do it. (It'd be better for them to set up a tiger team of their engineers with the equipment needed to suppress this possible bug.)

{^_^}


On 20220225 01:55:45, Conrad, PA5Y wrote:

By clean I mean - can I hear anything of sufficient magnitude to disturb the noise floor anywhere in band, and hence inhibit my ability to receive signals close to the noise floor. The noise floor in a semi-rural location on 28, 50 and 70MHz is not particularly low so I do not feel that this is unreasonable. The biggest problem with the IC7300 is the AM noise bump at 20kHz and 130kHz which is only 60dB down on the carrier when running at 30W on 28MHz. This power level is typical when driving an amplifier.  When modulated with an SSB signal this occupies a considerable amount of bandwidth.  The close in PN -s only -120dBc/Hz at 1kHz and  -130dBc/Hz at 10kHz. The composite noise is -115kHz at 10kHz, this is not what I would consider clean, even close in. The K3S( and a few others) is far better in this respect although the PA has quite poor linearity, especially on 6m.

 

The Hermes will do a much better job with any decent PA, even without pure signal. There are some spurs @ -65dBc which improve with a higher sample rate.  I have not checked these with the V2 firmware but I will do immediately I receive my Hermes from Apache.

 

I do not think that a transceiver at the IC-7300 price point has fixed pre-distortion. As you quite correctly say keeping it under control over temperature and voltage variation would be difficult. Also Icom would almost certainly have mentioned it in their advertising. What the IC7300 does well is manage audio overshoots by using a ‘look ahead’ algorithm. This is maybe where the impression of it having a clean TX comes from.

 

I think that the problem here is that so many transceivers are quite bad, so I can just about accept that the IC-7300 is less bad.

 

73

 

Conrad PA5Y

 

From: main@SDR-Radio.groups.io <main@SDR-Radio.groups.io> On Behalf Of jdow via groups.io
Sent: 25 February 2022 10:27
To:
main@SDR-Radio.groups.io
Subject: Re: [SDR-Radio] Open HPSDR Hermes (14 bit ADC, EP3C25) Transceiver Card

 

OK, please refresh my mind what you mean by "clean". It certainly appears to be sending something much closer to pure signal concentrated within its intended bandwidth than most other transmitters. I also understand that it is not as good as it can be with full active predistortion. Both might generate increased noise at some significant separation from the intended signal frequency. I am not sure of the mechanism by which this would take place.

As an ornery critter there is nothing I would sit down and declare "clean" without a definition of "clean". I guess I am asking for your definition of the term or even of the term "clean enough".

{O.O}



On 20220225 01:13:11, Conrad, PA5Y wrote:

I KNOW for a fact that the IC7300 is not clean. Please provide me some evidence to the contrary. I have measurements with a R&S FSWP Signal analyser out to a 1MHz BW. You guys are looking in an SSB BW which is fine unless you happen to be 130kHz away, then you will hear plenty of splatter from the IC7300. I tested the IC-7300 as a result of hearing this on 50MHz. In other words the lab tests were driven by on air experience.

 

You are spreading misleading and incorrect information.

 

73

 

Conrad PA5Y

 

From: main@SDR-Radio.groups.io <main@SDR-Radio.groups.io> On Behalf Of oldjackbob via groups.io
Sent: 24 February 2022 23:12
To:
main@SDR-Radio.groups.io
Subject: Re: [SDR-Radio] Open HPSDR Hermes (14 bit ADC, EP3C25) Transceiver Card

 

On Wed, Feb 23, 2022 at 12:24 PM, Max wrote:

I just think if we follow good design and signal chain management that superb, clean signals can also be generated without the need for PS, that's all.

Max,

I disagree. My signal is my signature. Audio clarity is admittedly important but what matters most to me is a splatter-free signal, and in that regard nothing comes close to what PS can produce. As I stated earlier, even the best Class A amplifiers only have -40dB splatter. PS starts at -60db and often pushes -70dB. That means that PS reduces splatter to less than 1% (and at times only 1/10 of 1%) of what even the best traditional equipment can produce.

I also agree with Simon that the 7300 (and also the 7610 for that matter) produces an extremely sharp-edged signal with unarguably less splatter than is achievable with any other non-ANAN radio. It was explained to me by Ray N5LAX that the reason those radios are so clean splatter-wise is because ICOM embedded an algorithm into the firmware that functions very similarly to PS in the sense that it corrects for non-linearity in the PA, but it is a fixed-value (i.e., static) correction only, not a real-time self-adjusting correction value such as is employed by PS. NOTE: I have not been able to verify that info, but that is what was told to me over-the-air by Ray when I commented that I had no idea how the 7300 could produce such a clean, sharp-edged signal. So I'm repeating it here.

IMO it's unwise and short-sighted to summarily dismiss the game-changing value that PS brings to the hobby. Its benefits are so unarguable that I (and Rob Sherwood) often wonder why the big-name radios don't offer it as a standard feature. It's free, so utilize it for goodness sake!

73,

Mark




 

 

 


Re: Open HPSDR Hermes (14 bit ADC, EP3C25) Transceiver Card

Conrad, PA5Y
 

Hello I never meant to come across as acrimonious, just insistent.

 

The plot is from a Rohde and Swartz FSUP signal source analyser in this case.

https://scdn.rohde-schwarz.com/ur/pws/dl_downloads/dl_common_library/dl_brochures_and_datasheets/pdf_1/FSUP_bro_en.pdf

 

The LO I used is from Kuhne electronics and is known as the XO1, it was intended as a 116MHz LO for use with 144 MHz transverters. It is not a custom product. It is simple Xtal oscillator with a narrow band PLL. The plot shows its performance when locked to a Leo Bodnar GPSDO at 10MHz.

 

It is normalised to 1Hz so in an SSB BW you can add 68dB to this plot assuming 2400Hz BW for SSB. I do not agree that this performance levels are only obtainable by special equipment. In fact older equipment like the IC-202 used to fair better. New equipment is making a pigs ear of this and transmitters are getting worse. A K3S and a transverter is all you need, or indeed a FDM Duo, Hermes, Flex or ANAN SDR.

 

These radios are all capable of meeting the code of conduct which in practice does have a positive effect. Not perfect but its existence is useful.

 

Now that we have such excellent receivers maybe we should pay attention to the TX chain?

 

This thread was about the Hermes, I apologise for hijacking it.

 

Regards

 

Conrad

 

 

From: main@SDR-Radio.groups.io <main@SDR-Radio.groups.io> On Behalf Of jdow via groups.io
Sent: 25 February 2022 14:30
To: main@SDR-Radio.groups.io
Subject: Re: [SDR-Radio] Open HPSDR Hermes (14 bit ADC, EP3C25) Transceiver Card

 

Um, I am not sure I understand that picture. That is the analyzer's specification or something very custom you have put together? I'm answering both emails here.

If that is the noise level you are insisting everybody meet I suspect you are going to be a very frustrated gentleman for the rest of your life. (Some old rigs never die. They simply make more noise.) The IC7300 might be capable of being tamed with a reference oscillator replacement. But I bet more bits in the D/A are required for that design than exist in reasonably priced D/A converters. Regardless "state of the art" only appears in hand tweaked radios or VERY expensive military or scientific equipment where there is a perceived need. (And codes of conduct are not worth the bits they fill on an exabyte storage array. Cats and humans cannot be herded.)

Even if 7300s are not "clean" as you would have it are they cleaner than their peers on the commercial market? From your complaints I suspect they are not. But it is a point worth asking. I ignored the argument until it got acrimonious.

{^_^}

On 20220225 04:03:42, Conrad, PA5Y wrote:

Hi, no it is actually 5 different IC7300s tested by 3 different people, including Rob Sherwood. if you have time you can see the plots and some other data that I posted earlier just do a search. I’m in my lunch break or I would do it for you.

 

Yes my TX IS that good but it is easier for me because I use 0dBm transverter drives at 28Mhz and transverters with high quality Xtal local oscillators. The 0dBm from either my K3S or TS-890S is very good indeed. IMD3 from both is better than -50dBc.

 

On 144 MHz,  PN noise at 1kHz separation is -144dBc/Hz and close to 156dBc/Hz at 10kHz. This is with the LO PLL active, free running it is a little better. Composite noise is the same as in this case it is PN dominated. IM3 is -38dBc but more importantly the 7th and 9th orders are better than -80dBc. This is achieved by using tetrode finals on all bands.

 

432 and 1296 are of course worse as the LOs are multiplied from Xtals in the VHF region. However my TX is some 40dB better than an IC-9700 at 1.3GHz at 10kHz separation.

 

 

Only 50MHz is a little worse due to my TS-890S PA linearity but with the noise on 6m being higher it is acceptable. When I am on FT8 where linearity does not matter it is superb. But who cares we are all on the same ‘channel’.

 

73

 

Conrad PA5Y

 

From: main@SDR-Radio.groups.io <main@SDR-Radio.groups.io> On Behalf Of jdow via groups.io
Sent: 25 February 2022 11:49
To: main@SDR-Radio.groups.io
Subject: Re: [SDR-Radio] Open HPSDR Hermes (14 bit ADC, EP3C25) Transceiver Card

 

I suspect your specification is still beyond the state of the art. Is your transmitter that good?

It sounds like the 7300 is cleaner than average close in but has some issues fairly far out. That is a little surprising. I wonder if the "IP+" technology is simply RF feedback to linearize the transmitter stages such as is seen in the old Collins kW SSB amplifiers. I can see that having an issue that depends on the charteristics of the feedback loop. But those are strange characteristics.

I take it the noise peaks are broadband, right? Do they depend on the transmit frequency in any way? It sounds very much like there is a defect in a specific radio near you. Is that the case or are hams measuring this in general? If this affects all the 7300s then the FPGA code will probably have to be reworked to fix the bug. I kinda wish I had one and a nice lab with lots of pertinent test equipment. I doubt Keysight and ICOM would set me up to do it. (It'd be better for them to set up a tiger team of their engineers with the equipment needed to suppress this possible bug.)

{^_^}


On 20220225 01:55:45, Conrad, PA5Y wrote:

By clean I mean - can I hear anything of sufficient magnitude to disturb the noise floor anywhere in band, and hence inhibit my ability to receive signals close to the noise floor. The noise floor in a semi-rural location on 28, 50 and 70MHz is not particularly low so I do not feel that this is unreasonable. The biggest problem with the IC7300 is the AM noise bump at 20kHz and 130kHz which is only 60dB down on the carrier when running at 30W on 28MHz. This power level is typical when driving an amplifier.  When modulated with an SSB signal this occupies a considerable amount of bandwidth.  The close in PN -s only -120dBc/Hz at 1kHz and  -130dBc/Hz at 10kHz. The composite noise is -115kHz at 10kHz, this is not what I would consider clean, even close in. The K3S( and a few others) is far better in this respect although the PA has quite poor linearity, especially on 6m.

 

The Hermes will do a much better job with any decent PA, even without pure signal. There are some spurs @ -65dBc which improve with a higher sample rate.  I have not checked these with the V2 firmware but I will do immediately I receive my Hermes from Apache.

 

I do not think that a transceiver at the IC-7300 price point has fixed pre-distortion. As you quite correctly say keeping it under control over temperature and voltage variation would be difficult. Also Icom would almost certainly have mentioned it in their advertising. What the IC7300 does well is manage audio overshoots by using a ‘look ahead’ algorithm. This is maybe where the impression of it having a clean TX comes from.

 

I think that the problem here is that so many transceivers are quite bad, so I can just about accept that the IC-7300 is less bad.

 

73

 

Conrad PA5Y

 

From: main@SDR-Radio.groups.io <main@SDR-Radio.groups.io> On Behalf Of jdow via groups.io
Sent: 25 February 2022 10:27
To:
main@SDR-Radio.groups.io
Subject: Re: [SDR-Radio] Open HPSDR Hermes (14 bit ADC, EP3C25) Transceiver Card

 

OK, please refresh my mind what you mean by "clean". It certainly appears to be sending something much closer to pure signal concentrated within its intended bandwidth than most other transmitters. I also understand that it is not as good as it can be with full active predistortion. Both might generate increased noise at some significant separation from the intended signal frequency. I am not sure of the mechanism by which this would take place.

As an ornery critter there is nothing I would sit down and declare "clean" without a definition of "clean". I guess I am asking for your definition of the term or even of the term "clean enough".

{O.O}



On 20220225 01:13:11, Conrad, PA5Y wrote:

I KNOW for a fact that the IC7300 is not clean. Please provide me some evidence to the contrary. I have measurements with a R&S FSWP Signal analyser out to a 1MHz BW. You guys are looking in an SSB BW which is fine unless you happen to be 130kHz away, then you will hear plenty of splatter from the IC7300. I tested the IC-7300 as a result of hearing this on 50MHz. In other words the lab tests were driven by on air experience.

 

You are spreading misleading and incorrect information.

 

73

 

Conrad PA5Y

 

From: main@SDR-Radio.groups.io <main@SDR-Radio.groups.io> On Behalf Of oldjackbob via groups.io
Sent: 24 February 2022 23:12
To:
main@SDR-Radio.groups.io
Subject: Re: [SDR-Radio] Open HPSDR Hermes (14 bit ADC, EP3C25) Transceiver Card

 

On Wed, Feb 23, 2022 at 12:24 PM, Max wrote:

I just think if we follow good design and signal chain management that superb, clean signals can also be generated without the need for PS, that's all.

Max,

I disagree. My signal is my signature. Audio clarity is admittedly important but what matters most to me is a splatter-free signal, and in that regard nothing comes close to what PS can produce. As I stated earlier, even the best Class A amplifiers only have -40dB splatter. PS starts at -60db and often pushes -70dB. That means that PS reduces splatter to less than 1% (and at times only 1/10 of 1%) of what even the best traditional equipment can produce.

I also agree with Simon that the 7300 (and also the 7610 for that matter) produces an extremely sharp-edged signal with unarguably less splatter than is achievable with any other non-ANAN radio. It was explained to me by Ray N5LAX that the reason those radios are so clean splatter-wise is because ICOM embedded an algorithm into the firmware that functions very similarly to PS in the sense that it corrects for non-linearity in the PA, but it is a fixed-value (i.e., static) correction only, not a real-time self-adjusting correction value such as is employed by PS. NOTE: I have not been able to verify that info, but that is what was told to me over-the-air by Ray when I commented that I had no idea how the 7300 could produce such a clean, sharp-edged signal. So I'm repeating it here.

IMO it's unwise and short-sighted to summarily dismiss the game-changing value that PS brings to the hobby. Its benefits are so unarguable that I (and Rob Sherwood) often wonder why the big-name radios don't offer it as a standard feature. It's free, so utilize it for goodness sake!

73,

Mark




 

 

 


Re: Open HPSDR Hermes (14 bit ADC, EP3C25) Transceiver Card

Mark Cayton
 

On Fri, Feb 25, 2022 at 04:03 AM, Conrad, PA5Y wrote:
The 0dBm from either my K3S or TS-890S is very good indeed. IMD3 from both is better than -50dBc.
Conrad,

I don't understand your numbers at all. A class A amplifier is capable of producing better IMD3 numbers than any other amp, and it is only capable of ~40dBc IMD3.

Rob Sherwood says the Collins 32S-3 is the best transmitter he has ever tested (other than an ANAN) and he compares all modern transmitters to the 32S-3. The numbers he measures on that transmitter are only -42dB referenced to PEP (see slide #29 in this pdf):

https://hamholiday.com/wp-content/uploads/2020/07/NC0B-Redwood-Empire-2k.pdf

Rob has stated that "Except for predistortion (PureSignal) available from Apache and Warren Pratt, and a couple of Yaesu class A rigs (if zero ALC and processing is run), all transmitters today are worse than a Collins 32S-3 as far as transmit IMD.":

https://groups.io/g/TS-890/message/772

So how on earth are you getting "better than -50dBc" IMD3 numbers on the 890S and K3S?

Mark


Re: Open HPSDR Hermes (14 bit ADC, EP3C25) Transceiver Card

jdow
 

Looking at the Keysight picture you posted it's hard to tell the characteristics of the peaks that appear beside the (was it?) 28.4 MHz signal. (The screen notation of 390 kHz is confusing. That is the marker's offset?)

It appears like the 7300 is using a digital frequency synthesizer with way too few bits to make a good signal. If I got a rig that bad I think I'd have some stern words with ICOM about it. While it might be marginally legal it is unethical to sell something that bad. (And at 100W I thought the limit was -70 dB in the US.

{^_^}

On 20220225 04:03:42, Conrad, PA5Y wrote:

Hi, no it is actually 5 different IC7300s tested by 3 different people, including Rob Sherwood. if you have time you can see the plots and some other data that I posted earlier just do a search. I’m in my lunch break or I would do it for you.

 

Yes my TX IS that good but it is easier for me because I use 0dBm transverter drives at 28Mhz and transverters with high quality Xtal local oscillators. The 0dBm from either my K3S or TS-890S is very good indeed. IMD3 from both is better than -50dBc.

 

On 144 MHz,  PN noise at 1kHz separation is -144dBc/Hz and close to 156dBc/Hz at 10kHz. This is with the LO PLL active, free running it is a little better. Composite noise is the same as in this case it is PN dominated. IM3 is -38dBc but more importantly the 7th and 9th orders are better than -80dBc. This is achieved by using tetrode finals on all bands.

 

432 and 1296 are of course worse as the LOs are multiplied from Xtals in the VHF region. However my TX is some 40dB better than an IC-9700 at 1.3GHz at 10kHz separation.

 

 

Only 50MHz is a little worse due to my TS-890S PA linearity but with the noise on 6m being higher it is acceptable. When I am on FT8 where linearity does not matter it is superb. But who cares we are all on the same ‘channel’.

 

73

 

Conrad PA5Y

 

From: main@SDR-Radio.groups.io <main@SDR-Radio.groups.io> On Behalf Of jdow via groups.io
Sent: 25 February 2022 11:49
To: main@SDR-Radio.groups.io
Subject: Re: [SDR-Radio] Open HPSDR Hermes (14 bit ADC, EP3C25) Transceiver Card

 

I suspect your specification is still beyond the state of the art. Is your transmitter that good?

It sounds like the 7300 is cleaner than average close in but has some issues fairly far out. That is a little surprising. I wonder if the "IP+" technology is simply RF feedback to linearize the transmitter stages such as is seen in the old Collins kW SSB amplifiers. I can see that having an issue that depends on the charteristics of the feedback loop. But those are strange characteristics.

I take it the noise peaks are broadband, right? Do they depend on the transmit frequency in any way? It sounds very much like there is a defect in a specific radio near you. Is that the case or are hams measuring this in general? If this affects all the 7300s then the FPGA code will probably have to be reworked to fix the bug. I kinda wish I had one and a nice lab with lots of pertinent test equipment. I doubt Keysight and ICOM would set me up to do it. (It'd be better for them to set up a tiger team of their engineers with the equipment needed to suppress this possible bug.)

{^_^}

On 20220225 01:55:45, Conrad, PA5Y wrote:

By clean I mean - can I hear anything of sufficient magnitude to disturb the noise floor anywhere in band, and hence inhibit my ability to receive signals close to the noise floor. The noise floor in a semi-rural location on 28, 50 and 70MHz is not particularly low so I do not feel that this is unreasonable. The biggest problem with the IC7300 is the AM noise bump at 20kHz and 130kHz which is only 60dB down on the carrier when running at 30W on 28MHz. This power level is typical when driving an amplifier.  When modulated with an SSB signal this occupies a considerable amount of bandwidth.  The close in PN -s only -120dBc/Hz at 1kHz and  -130dBc/Hz at 10kHz. The composite noise is -115kHz at 10kHz, this is not what I would consider clean, even close in. The K3S( and a few others) is far better in this respect although the PA has quite poor linearity, especially on 6m.

 

The Hermes will do a much better job with any decent PA, even without pure signal. There are some spurs @ -65dBc which improve with a higher sample rate.  I have not checked these with the V2 firmware but I will do immediately I receive my Hermes from Apache.

 

I do not think that a transceiver at the IC-7300 price point has fixed pre-distortion. As you quite correctly say keeping it under control over temperature and voltage variation would be difficult. Also Icom would almost certainly have mentioned it in their advertising. What the IC7300 does well is manage audio overshoots by using a ‘look ahead’ algorithm. This is maybe where the impression of it having a clean TX comes from.

 

I think that the problem here is that so many transceivers are quite bad, so I can just about accept that the IC-7300 is less bad.

 

73

 

Conrad PA5Y

 

From: main@SDR-Radio.groups.io <main@SDR-Radio.groups.io> On Behalf Of jdow via groups.io
Sent: 25 February 2022 10:27
To:
main@SDR-Radio.groups.io
Subject: Re: [SDR-Radio] Open HPSDR Hermes (14 bit ADC, EP3C25) Transceiver Card

 

OK, please refresh my mind what you mean by "clean". It certainly appears to be sending something much closer to pure signal concentrated within its intended bandwidth than most other transmitters. I also understand that it is not as good as it can be with full active predistortion. Both might generate increased noise at some significant separation from the intended signal frequency. I am not sure of the mechanism by which this would take place.

As an ornery critter there is nothing I would sit down and declare "clean" without a definition of "clean". I guess I am asking for your definition of the term or even of the term "clean enough".

{O.O}


On 20220225 01:13:11, Conrad, PA5Y wrote:

I KNOW for a fact that the IC7300 is not clean. Please provide me some evidence to the contrary. I have measurements with a R&S FSWP Signal analyser out to a 1MHz BW. You guys are looking in an SSB BW which is fine unless you happen to be 130kHz away, then you will hear plenty of splatter from the IC7300. I tested the IC-7300 as a result of hearing this on 50MHz. In other words the lab tests were driven by on air experience.

 

You are spreading misleading and incorrect information.

 

73

 

Conrad PA5Y

 

From: main@SDR-Radio.groups.io <main@SDR-Radio.groups.io> On Behalf Of oldjackbob via groups.io
Sent: 24 February 2022 23:12
To:
main@SDR-Radio.groups.io
Subject: Re: [SDR-Radio] Open HPSDR Hermes (14 bit ADC, EP3C25) Transceiver Card

 

On Wed, Feb 23, 2022 at 12:24 PM, Max wrote:

I just think if we follow good design and signal chain management that superb, clean signals can also be generated without the need for PS, that's all.

Max,

I disagree. My signal is my signature. Audio clarity is admittedly important but what matters most to me is a splatter-free signal, and in that regard nothing comes close to what PS can produce. As I stated earlier, even the best Class A amplifiers only have -40dB splatter. PS starts at -60db and often pushes -70dB. That means that PS reduces splatter to less than 1% (and at times only 1/10 of 1%) of what even the best traditional equipment can produce.

I also agree with Simon that the 7300 (and also the 7610 for that matter) produces an extremely sharp-edged signal with unarguably less splatter than is achievable with any other non-ANAN radio. It was explained to me by Ray N5LAX that the reason those radios are so clean splatter-wise is because ICOM embedded an algorithm into the firmware that functions very similarly to PS in the sense that it corrects for non-linearity in the PA, but it is a fixed-value (i.e., static) correction only, not a real-time self-adjusting correction value such as is employed by PS. NOTE: I have not been able to verify that info, but that is what was told to me over-the-air by Ray when I commented that I had no idea how the 7300 could produce such a clean, sharp-edged signal. So I'm repeating it here.

IMO it's unwise and short-sighted to summarily dismiss the game-changing value that PS brings to the hobby. Its benefits are so unarguable that I (and Rob Sherwood) often wonder why the big-name radios don't offer it as a standard feature. It's free, so utilize it for goodness sake!

73,

Mark



 

 



Re: Open HPSDR Hermes (14 bit ADC, EP3C25) Transceiver Card

jdow
 

Um, I am not sure I understand that picture. That is the analyzer's specification or something very custom you have put together? I'm answering both emails here.

If that is the noise level you are insisting everybody meet I suspect you are going to be a very frustrated gentleman for the rest of your life. (Some old rigs never die. They simply make more noise.) The IC7300 might be capable of being tamed with a reference oscillator replacement. But I bet more bits in the D/A are required for that design than exist in reasonably priced D/A converters. Regardless "state of the art" only appears in hand tweaked radios or VERY expensive military or scientific equipment where there is a perceived need. (And codes of conduct are not worth the bits they fill on an exabyte storage array. Cats and humans cannot be herded.)

Even if 7300s are not "clean" as you would have it are they cleaner than their peers on the commercial market? From your complaints I suspect they are not. But it is a point worth asking. I ignored the argument until it got acrimonious.

{^_^}

On 20220225 04:03:42, Conrad, PA5Y wrote:

Hi, no it is actually 5 different IC7300s tested by 3 different people, including Rob Sherwood. if you have time you can see the plots and some other data that I posted earlier just do a search. I’m in my lunch break or I would do it for you.

 

Yes my TX IS that good but it is easier for me because I use 0dBm transverter drives at 28Mhz and transverters with high quality Xtal local oscillators. The 0dBm from either my K3S or TS-890S is very good indeed. IMD3 from both is better than -50dBc.

 

On 144 MHz,  PN noise at 1kHz separation is -144dBc/Hz and close to 156dBc/Hz at 10kHz. This is with the LO PLL active, free running it is a little better. Composite noise is the same as in this case it is PN dominated. IM3 is -38dBc but more importantly the 7th and 9th orders are better than -80dBc. This is achieved by using tetrode finals on all bands.

 

432 and 1296 are of course worse as the LOs are multiplied from Xtals in the VHF region. However my TX is some 40dB better than an IC-9700 at 1.3GHz at 10kHz separation.

 

 

Only 50MHz is a little worse due to my TS-890S PA linearity but with the noise on 6m being higher it is acceptable. When I am on FT8 where linearity does not matter it is superb. But who cares we are all on the same ‘channel’.

 

73

 

Conrad PA5Y

 

From: main@SDR-Radio.groups.io <main@SDR-Radio.groups.io> On Behalf Of jdow via groups.io
Sent: 25 February 2022 11:49
To: main@SDR-Radio.groups.io
Subject: Re: [SDR-Radio] Open HPSDR Hermes (14 bit ADC, EP3C25) Transceiver Card

 

I suspect your specification is still beyond the state of the art. Is your transmitter that good?

It sounds like the 7300 is cleaner than average close in but has some issues fairly far out. That is a little surprising. I wonder if the "IP+" technology is simply RF feedback to linearize the transmitter stages such as is seen in the old Collins kW SSB amplifiers. I can see that having an issue that depends on the charteristics of the feedback loop. But those are strange characteristics.

I take it the noise peaks are broadband, right? Do they depend on the transmit frequency in any way? It sounds very much like there is a defect in a specific radio near you. Is that the case or are hams measuring this in general? If this affects all the 7300s then the FPGA code will probably have to be reworked to fix the bug. I kinda wish I had one and a nice lab with lots of pertinent test equipment. I doubt Keysight and ICOM would set me up to do it. (It'd be better for them to set up a tiger team of their engineers with the equipment needed to suppress this possible bug.)

{^_^}

On 20220225 01:55:45, Conrad, PA5Y wrote:

By clean I mean - can I hear anything of sufficient magnitude to disturb the noise floor anywhere in band, and hence inhibit my ability to receive signals close to the noise floor. The noise floor in a semi-rural location on 28, 50 and 70MHz is not particularly low so I do not feel that this is unreasonable. The biggest problem with the IC7300 is the AM noise bump at 20kHz and 130kHz which is only 60dB down on the carrier when running at 30W on 28MHz. This power level is typical when driving an amplifier.  When modulated with an SSB signal this occupies a considerable amount of bandwidth.  The close in PN -s only -120dBc/Hz at 1kHz and  -130dBc/Hz at 10kHz. The composite noise is -115kHz at 10kHz, this is not what I would consider clean, even close in. The K3S( and a few others) is far better in this respect although the PA has quite poor linearity, especially on 6m.

 

The Hermes will do a much better job with any decent PA, even without pure signal. There are some spurs @ -65dBc which improve with a higher sample rate.  I have not checked these with the V2 firmware but I will do immediately I receive my Hermes from Apache.

 

I do not think that a transceiver at the IC-7300 price point has fixed pre-distortion. As you quite correctly say keeping it under control over temperature and voltage variation would be difficult. Also Icom would almost certainly have mentioned it in their advertising. What the IC7300 does well is manage audio overshoots by using a ‘look ahead’ algorithm. This is maybe where the impression of it having a clean TX comes from.

 

I think that the problem here is that so many transceivers are quite bad, so I can just about accept that the IC-7300 is less bad.

 

73

 

Conrad PA5Y

 

From: main@SDR-Radio.groups.io <main@SDR-Radio.groups.io> On Behalf Of jdow via groups.io
Sent: 25 February 2022 10:27
To:
main@SDR-Radio.groups.io
Subject: Re: [SDR-Radio] Open HPSDR Hermes (14 bit ADC, EP3C25) Transceiver Card

 

OK, please refresh my mind what you mean by "clean". It certainly appears to be sending something much closer to pure signal concentrated within its intended bandwidth than most other transmitters. I also understand that it is not as good as it can be with full active predistortion. Both might generate increased noise at some significant separation from the intended signal frequency. I am not sure of the mechanism by which this would take place.

As an ornery critter there is nothing I would sit down and declare "clean" without a definition of "clean". I guess I am asking for your definition of the term or even of the term "clean enough".

{O.O}


On 20220225 01:13:11, Conrad, PA5Y wrote:

I KNOW for a fact that the IC7300 is not clean. Please provide me some evidence to the contrary. I have measurements with a R&S FSWP Signal analyser out to a 1MHz BW. You guys are looking in an SSB BW which is fine unless you happen to be 130kHz away, then you will hear plenty of splatter from the IC7300. I tested the IC-7300 as a result of hearing this on 50MHz. In other words the lab tests were driven by on air experience.

 

You are spreading misleading and incorrect information.

 

73

 

Conrad PA5Y

 

From: main@SDR-Radio.groups.io <main@SDR-Radio.groups.io> On Behalf Of oldjackbob via groups.io
Sent: 24 February 2022 23:12
To:
main@SDR-Radio.groups.io
Subject: Re: [SDR-Radio] Open HPSDR Hermes (14 bit ADC, EP3C25) Transceiver Card

 

On Wed, Feb 23, 2022 at 12:24 PM, Max wrote:

I just think if we follow good design and signal chain management that superb, clean signals can also be generated without the need for PS, that's all.

Max,

I disagree. My signal is my signature. Audio clarity is admittedly important but what matters most to me is a splatter-free signal, and in that regard nothing comes close to what PS can produce. As I stated earlier, even the best Class A amplifiers only have -40dB splatter. PS starts at -60db and often pushes -70dB. That means that PS reduces splatter to less than 1% (and at times only 1/10 of 1%) of what even the best traditional equipment can produce.

I also agree with Simon that the 7300 (and also the 7610 for that matter) produces an extremely sharp-edged signal with unarguably less splatter than is achievable with any other non-ANAN radio. It was explained to me by Ray N5LAX that the reason those radios are so clean splatter-wise is because ICOM embedded an algorithm into the firmware that functions very similarly to PS in the sense that it corrects for non-linearity in the PA, but it is a fixed-value (i.e., static) correction only, not a real-time self-adjusting correction value such as is employed by PS. NOTE: I have not been able to verify that info, but that is what was told to me over-the-air by Ray when I commented that I had no idea how the 7300 could produce such a clean, sharp-edged signal. So I'm repeating it here.

IMO it's unwise and short-sighted to summarily dismiss the game-changing value that PS brings to the hobby. Its benefits are so unarguable that I (and Rob Sherwood) often wonder why the big-name radios don't offer it as a standard feature. It's free, so utilize it for goodness sake!

73,

Mark



 

 



Re: Open HPSDR Hermes (14 bit ADC, EP3C25) Transceiver Card

Conrad, PA5Y
 

Hello Simon, I had a choice between 6m EME and 6 and 4m with ‘normal’ antennas. I chose 6m EME but I am not so sure it was the right decision after recent storms. I have 6m/4m dual band antenna ready to go up. I will decide in April what to do. I do like 4m.

 

Good luck with the new PA.

 

73

 

Conrad

 

From: main@SDR-Radio.groups.io <main@SDR-Radio.groups.io> On Behalf Of Simon Brown via groups.io
Sent: 25 February 2022 11:43
To: main@SDR-Radio.groups.io
Subject: Re: [SDR-Radio] Open HPSDR Hermes (14 bit ADC, EP3C25) Transceiver Card

 

Conrad,

 

80m SSB DXing has died as death – despite excellent conditions very few people coming on. Are you on 4m – if so I’ll be testing my new legal limit amplifier this afternoon.

 

Simon Brown, G4ELI

https://www.sdr-radio.com

 

From: main@SDR-Radio.groups.io <main@SDR-Radio.groups.io> On Behalf Of Conrad, PA5Y
Sent: 25 February 2022 10:28
To: main@SDR-Radio.groups.io
Subject: Re: [SDR-Radio] Open HPSDR Hermes (14 bit ADC, EP3C25) Transceiver Card

 

You are not painting an attractive picture Simon.

 

However when I get older and maintaining EME antennas gets too much for me.  I do always fancy 160 and 80m. Mainly because it appears to be challenging. I do plan to put up an EWE next winter just to get a feel for it. I’m not disinterested in the idea.

 

Conrad

 

From: main@SDR-Radio.groups.io <main@SDR-Radio.groups.io> On Behalf Of Simon Brown via groups.io
Sent: 25 February 2022 11:24
To: main@SDR-Radio.groups.io
Subject: Re: [SDR-Radio] Open HPSDR Hermes (14 bit ADC, EP3C25) Transceiver Card

 

Try listening in the 80m DX window in New England – AG1J uses a ~60 year-old SSB rig. Wide hardly starts to describe it, I think it’s a phasing exciter with obligatory after-burner.

 

Simon Brown, G4ELI

https://www.sdr-radio.com

 

From: main@SDR-Radio.groups.io <main@SDR-Radio.groups.io> On Behalf Of Conrad, PA5Y
Sent: 25 February 2022 09:56
To: main@SDR-Radio.groups.io
Subject: Re: [SDR-Radio] Open HPSDR Hermes (14 bit ADC, EP3C25) Transceiver Card

 

By clean I mean - can I hear anything of sufficient magnitude to disturb the noise floor anywhere in band, and hence inhibit my ability to receive signals close to the noise floor. The noise floor in a semi-rural location on 28, 50 and 70MHz is not particularly low so I do not feel that this is unreasonable. The biggest problem with the IC7300 is the AM noise bump at 20kHz and 130kHz which is only 60dB down on the carrier when running at 30W on 28MHz. This power level is typical when driving an amplifier.  When modulated with an SSB signal this occupies a considerable amount of bandwidth.  The close in PN -s only -120dBc/Hz at 1kHz and  -130dBc/Hz at 10kHz. The composite noise is -115kHz at 10kHz, this is not what I would consider clean, even close in. The K3S( and a few others) is far better in this respect although the PA has quite poor linearity, especially on 6m.

 

The Hermes will do a much better job with any decent PA, even without pure signal. There are some spurs @ -65dBc which improve with a higher sample rate.  I have not checked these with the V2 firmware but I will do immediately I receive my Hermes from Apache.

 

I do not think that a transceiver at the IC-7300 price point has fixed pre-distortion. As you quite correctly say keeping it under control over temperature and voltage variation would be difficult. Also Icom would almost certainly have mentioned it in their advertising. What the IC7300 does well is manage audio overshoots by using a ‘look ahead’ algorithm. This is maybe where the impression of it having a clean TX comes from.

 

I think that the problem here is that so many transceivers are quite bad, so I can just about accept that the IC-7300 is less bad.

 

73

 

Conrad PA5Y

 

From: main@SDR-Radio.groups.io <main@SDR-Radio.groups.io> On Behalf Of jdow via groups.io
Sent: 25 February 2022 10:27
To: main@SDR-Radio.groups.io
Subject: Re: [SDR-Radio] Open HPSDR Hermes (14 bit ADC, EP3C25) Transceiver Card

 

OK, please refresh my mind what you mean by "clean". It certainly appears to be sending something much closer to pure signal concentrated within its intended bandwidth than most other transmitters. I also understand that it is not as good as it can be with full active predistortion. Both might generate increased noise at some significant separation from the intended signal frequency. I am not sure of the mechanism by which this would take place.

As an ornery critter there is nothing I would sit down and declare "clean" without a definition of "clean". I guess I am asking for your definition of the term or even of the term "clean enough".

{O.O}

On 20220225 01:13:11, Conrad, PA5Y wrote:

I KNOW for a fact that the IC7300 is not clean. Please provide me some evidence to the contrary. I have measurements with a R&S FSWP Signal analyser out to a 1MHz BW. You guys are looking in an SSB BW which is fine unless you happen to be 130kHz away, then you will hear plenty of splatter from the IC7300. I tested the IC-7300 as a result of hearing this on 50MHz. In other words the lab tests were driven by on air experience.

 

You are spreading misleading and incorrect information.

 

73

 

Conrad PA5Y

 

From: main@SDR-Radio.groups.io <main@SDR-Radio.groups.io> On Behalf Of oldjackbob via groups.io
Sent: 24 February 2022 23:12
To:
main@SDR-Radio.groups.io
Subject: Re: [SDR-Radio] Open HPSDR Hermes (14 bit ADC, EP3C25) Transceiver Card

 

On Wed, Feb 23, 2022 at 12:24 PM, Max wrote:

I just think if we follow good design and signal chain management that superb, clean signals can also be generated without the need for PS, that's all.

Max,

I disagree. My signal is my signature. Audio clarity is admittedly important but what matters most to me is a splatter-free signal, and in that regard nothing comes close to what PS can produce. As I stated earlier, even the best Class A amplifiers only have -40dB splatter. PS starts at -60db and often pushes -70dB. That means that PS reduces splatter to less than 1% (and at times only 1/10 of 1%) of what even the best traditional equipment can produce.

I also agree with Simon that the 7300 (and also the 7610 for that matter) produces an extremely sharp-edged signal with unarguably less splatter than is achievable with any other non-ANAN radio. It was explained to me by Ray N5LAX that the reason those radios are so clean splatter-wise is because ICOM embedded an algorithm into the firmware that functions very similarly to PS in the sense that it corrects for non-linearity in the PA, but it is a fixed-value (i.e., static) correction only, not a real-time self-adjusting correction value such as is employed by PS. NOTE: I have not been able to verify that info, but that is what was told to me over-the-air by Ray when I commented that I had no idea how the 7300 could produce such a clean, sharp-edged signal. So I'm repeating it here.

IMO it's unwise and short-sighted to summarily dismiss the game-changing value that PS brings to the hobby. Its benefits are so unarguable that I (and Rob Sherwood) often wonder why the big-name radios don't offer it as a standard feature. It's free, so utilize it for goodness sake!

73,

Mark

 


--

- + - + -

Please use https://forum.sdr-radio.com:4499/ when posting questions or problems.


--

- + - + -

Please use https://forum.sdr-radio.com:4499/ when posting questions or problems.


Re: Open HPSDR Hermes (14 bit ADC, EP3C25) Transceiver Card

Conrad, PA5Y
 

Forgot to mention that in high amateur density areas in VHF contests for stations using high power there is a ‘code of conduct’.  Perhaps if you have time you may want to watch this video:

https://www.youtube.com/watch?v=wHPpP2FJqrU

 

It discusses how this code of conduct was derived and shows that this performance is achievable and is state of the art.  Of course this is far more important on 50MHz and above. For HF we can relax things significantly but it is still no fun if you are close to a bad radio 90dB above your noise floor.

 

IP+ is only applicable to the RX ADC I believe.

 

I will try to get on HF this year so I have a better feel for what the majority of people have to deal with. I know that Rob Sherwood is putting significant effort in highlighting the deficiencies in our transmitters. His aim is to get the ‘big 3’ to improve things.

 

Regards

 

Conrad PA5Y

 

 

 

 

From: main@SDR-Radio.groups.io <main@SDR-Radio.groups.io> On Behalf Of jdow via groups.io
Sent: 25 February 2022 11:49
To: main@SDR-Radio.groups.io
Subject: Re: [SDR-Radio] Open HPSDR Hermes (14 bit ADC, EP3C25) Transceiver Card

 

I suspect your specification is still beyond the state of the art. Is your transmitter that good?

It sounds like the 7300 is cleaner than average close in but has some issues fairly far out. That is a little surprising. I wonder if the "IP+" technology is simply RF feedback to linearize the transmitter stages such as is seen in the old Collins kW SSB amplifiers. I can see that having an issue that depends on the charteristics of the feedback loop. But those are strange characteristics.

I take it the noise peaks are broadband, right? Do they depend on the transmit frequency in any way? It sounds very much like there is a defect in a specific radio near you. Is that the case or are hams measuring this in general? If this affects all the 7300s then the FPGA code will probably have to be reworked to fix the bug. I kinda wish I had one and a nice lab with lots of pertinent test equipment. I doubt Keysight and ICOM would set me up to do it. (It'd be better for them to set up a tiger team of their engineers with the equipment needed to suppress this possible bug.)

{^_^}

On 20220225 01:55:45, Conrad, PA5Y wrote:

By clean I mean - can I hear anything of sufficient magnitude to disturb the noise floor anywhere in band, and hence inhibit my ability to receive signals close to the noise floor. The noise floor in a semi-rural location on 28, 50 and 70MHz is not particularly low so I do not feel that this is unreasonable. The biggest problem with the IC7300 is the AM noise bump at 20kHz and 130kHz which is only 60dB down on the carrier when running at 30W on 28MHz. This power level is typical when driving an amplifier.  When modulated with an SSB signal this occupies a considerable amount of bandwidth.  The close in PN -s only -120dBc/Hz at 1kHz and  -130dBc/Hz at 10kHz. The composite noise is -115kHz at 10kHz, this is not what I would consider clean, even close in. The K3S( and a few others) is far better in this respect although the PA has quite poor linearity, especially on 6m.

 

The Hermes will do a much better job with any decent PA, even without pure signal. There are some spurs @ -65dBc which improve with a higher sample rate.  I have not checked these with the V2 firmware but I will do immediately I receive my Hermes from Apache.

 

I do not think that a transceiver at the IC-7300 price point has fixed pre-distortion. As you quite correctly say keeping it under control over temperature and voltage variation would be difficult. Also Icom would almost certainly have mentioned it in their advertising. What the IC7300 does well is manage audio overshoots by using a ‘look ahead’ algorithm. This is maybe where the impression of it having a clean TX comes from.

 

I think that the problem here is that so many transceivers are quite bad, so I can just about accept that the IC-7300 is less bad.

 

73

 

Conrad PA5Y

 

From: main@SDR-Radio.groups.io <main@SDR-Radio.groups.io> On Behalf Of jdow via groups.io
Sent: 25 February 2022 10:27
To: main@SDR-Radio.groups.io
Subject: Re: [SDR-Radio] Open HPSDR Hermes (14 bit ADC, EP3C25) Transceiver Card

 

OK, please refresh my mind what you mean by "clean". It certainly appears to be sending something much closer to pure signal concentrated within its intended bandwidth than most other transmitters. I also understand that it is not as good as it can be with full active predistortion. Both might generate increased noise at some significant separation from the intended signal frequency. I am not sure of the mechanism by which this would take place.

As an ornery critter there is nothing I would sit down and declare "clean" without a definition of "clean". I guess I am asking for your definition of the term or even of the term "clean enough".

{O.O}


On 20220225 01:13:11, Conrad, PA5Y wrote:

I KNOW for a fact that the IC7300 is not clean. Please provide me some evidence to the contrary. I have measurements with a R&S FSWP Signal analyser out to a 1MHz BW. You guys are looking in an SSB BW which is fine unless you happen to be 130kHz away, then you will hear plenty of splatter from the IC7300. I tested the IC-7300 as a result of hearing this on 50MHz. In other words the lab tests were driven by on air experience.

 

You are spreading misleading and incorrect information.

 

73

 

Conrad PA5Y

 

From: main@SDR-Radio.groups.io <main@SDR-Radio.groups.io> On Behalf Of oldjackbob via groups.io
Sent: 24 February 2022 23:12
To:
main@SDR-Radio.groups.io
Subject: Re: [SDR-Radio] Open HPSDR Hermes (14 bit ADC, EP3C25) Transceiver Card

 

On Wed, Feb 23, 2022 at 12:24 PM, Max wrote:

I just think if we follow good design and signal chain management that superb, clean signals can also be generated without the need for PS, that's all.

Max,

I disagree. My signal is my signature. Audio clarity is admittedly important but what matters most to me is a splatter-free signal, and in that regard nothing comes close to what PS can produce. As I stated earlier, even the best Class A amplifiers only have -40dB splatter. PS starts at -60db and often pushes -70dB. That means that PS reduces splatter to less than 1% (and at times only 1/10 of 1%) of what even the best traditional equipment can produce.

I also agree with Simon that the 7300 (and also the 7610 for that matter) produces an extremely sharp-edged signal with unarguably less splatter than is achievable with any other non-ANAN radio. It was explained to me by Ray N5LAX that the reason those radios are so clean splatter-wise is because ICOM embedded an algorithm into the firmware that functions very similarly to PS in the sense that it corrects for non-linearity in the PA, but it is a fixed-value (i.e., static) correction only, not a real-time self-adjusting correction value such as is employed by PS. NOTE: I have not been able to verify that info, but that is what was told to me over-the-air by Ray when I commented that I had no idea how the 7300 could produce such a clean, sharp-edged signal. So I'm repeating it here.

IMO it's unwise and short-sighted to summarily dismiss the game-changing value that PS brings to the hobby. Its benefits are so unarguable that I (and Rob Sherwood) often wonder why the big-name radios don't offer it as a standard feature. It's free, so utilize it for goodness sake!

73,

Mark



 

 


Re: Open HPSDR Hermes (14 bit ADC, EP3C25) Transceiver Card

Conrad, PA5Y
 

Hi, no it is actually 5 different IC7300s tested by 3 different people, including Rob Sherwood. if you have time you can see the plots and some other data that I posted earlier just do a search. I’m in my lunch break or I would do it for you.

 

Yes my TX IS that good but it is easier for me because I use 0dBm transverter drives at 28Mhz and transverters with high quality Xtal local oscillators. The 0dBm from either my K3S or TS-890S is very good indeed. IMD3 from both is better than -50dBc.

 

On 144 MHz,  PN noise at 1kHz separation is -144dBc/Hz and close to 156dBc/Hz at 10kHz. This is with the LO PLL active, free running it is a little better. Composite noise is the same as in this case it is PN dominated. IM3 is -38dBc but more importantly the 7th and 9th orders are better than -80dBc. This is achieved by using tetrode finals on all bands.

 

432 and 1296 are of course worse as the LOs are multiplied from Xtals in the VHF region. However my TX is some 40dB better than an IC-9700 at 1.3GHz at 10kHz separation.

 

 

Only 50MHz is a little worse due to my TS-890S PA linearity but with the noise on 6m being higher it is acceptable. When I am on FT8 where linearity does not matter it is superb. But who cares we are all on the same ‘channel’.

 

73

 

Conrad PA5Y

 

From: main@SDR-Radio.groups.io <main@SDR-Radio.groups.io> On Behalf Of jdow via groups.io
Sent: 25 February 2022 11:49
To: main@SDR-Radio.groups.io
Subject: Re: [SDR-Radio] Open HPSDR Hermes (14 bit ADC, EP3C25) Transceiver Card

 

I suspect your specification is still beyond the state of the art. Is your transmitter that good?

It sounds like the 7300 is cleaner than average close in but has some issues fairly far out. That is a little surprising. I wonder if the "IP+" technology is simply RF feedback to linearize the transmitter stages such as is seen in the old Collins kW SSB amplifiers. I can see that having an issue that depends on the charteristics of the feedback loop. But those are strange characteristics.

I take it the noise peaks are broadband, right? Do they depend on the transmit frequency in any way? It sounds very much like there is a defect in a specific radio near you. Is that the case or are hams measuring this in general? If this affects all the 7300s then the FPGA code will probably have to be reworked to fix the bug. I kinda wish I had one and a nice lab with lots of pertinent test equipment. I doubt Keysight and ICOM would set me up to do it. (It'd be better for them to set up a tiger team of their engineers with the equipment needed to suppress this possible bug.)

{^_^}

On 20220225 01:55:45, Conrad, PA5Y wrote:

By clean I mean - can I hear anything of sufficient magnitude to disturb the noise floor anywhere in band, and hence inhibit my ability to receive signals close to the noise floor. The noise floor in a semi-rural location on 28, 50 and 70MHz is not particularly low so I do not feel that this is unreasonable. The biggest problem with the IC7300 is the AM noise bump at 20kHz and 130kHz which is only 60dB down on the carrier when running at 30W on 28MHz. This power level is typical when driving an amplifier.  When modulated with an SSB signal this occupies a considerable amount of bandwidth.  The close in PN -s only -120dBc/Hz at 1kHz and  -130dBc/Hz at 10kHz. The composite noise is -115kHz at 10kHz, this is not what I would consider clean, even close in. The K3S( and a few others) is far better in this respect although the PA has quite poor linearity, especially on 6m.

 

The Hermes will do a much better job with any decent PA, even without pure signal. There are some spurs @ -65dBc which improve with a higher sample rate.  I have not checked these with the V2 firmware but I will do immediately I receive my Hermes from Apache.

 

I do not think that a transceiver at the IC-7300 price point has fixed pre-distortion. As you quite correctly say keeping it under control over temperature and voltage variation would be difficult. Also Icom would almost certainly have mentioned it in their advertising. What the IC7300 does well is manage audio overshoots by using a ‘look ahead’ algorithm. This is maybe where the impression of it having a clean TX comes from.

 

I think that the problem here is that so many transceivers are quite bad, so I can just about accept that the IC-7300 is less bad.

 

73

 

Conrad PA5Y

 

From: main@SDR-Radio.groups.io <main@SDR-Radio.groups.io> On Behalf Of jdow via groups.io
Sent: 25 February 2022 10:27
To:
main@SDR-Radio.groups.io
Subject: Re: [SDR-Radio] Open HPSDR Hermes (14 bit ADC, EP3C25) Transceiver Card

 

OK, please refresh my mind what you mean by "clean". It certainly appears to be sending something much closer to pure signal concentrated within its intended bandwidth than most other transmitters. I also understand that it is not as good as it can be with full active predistortion. Both might generate increased noise at some significant separation from the intended signal frequency. I am not sure of the mechanism by which this would take place.

As an ornery critter there is nothing I would sit down and declare "clean" without a definition of "clean". I guess I am asking for your definition of the term or even of the term "clean enough".

{O.O}


On 20220225 01:13:11, Conrad, PA5Y wrote:

I KNOW for a fact that the IC7300 is not clean. Please provide me some evidence to the contrary. I have measurements with a R&S FSWP Signal analyser out to a 1MHz BW. You guys are looking in an SSB BW which is fine unless you happen to be 130kHz away, then you will hear plenty of splatter from the IC7300. I tested the IC-7300 as a result of hearing this on 50MHz. In other words the lab tests were driven by on air experience.

 

You are spreading misleading and incorrect information.

 

73

 

Conrad PA5Y

 

From: main@SDR-Radio.groups.io <main@SDR-Radio.groups.io> On Behalf Of oldjackbob via groups.io
Sent: 24 February 2022 23:12
To:
main@SDR-Radio.groups.io
Subject: Re: [SDR-Radio] Open HPSDR Hermes (14 bit ADC, EP3C25) Transceiver Card

 

On Wed, Feb 23, 2022 at 12:24 PM, Max wrote:

I just think if we follow good design and signal chain management that superb, clean signals can also be generated without the need for PS, that's all.

Max,

I disagree. My signal is my signature. Audio clarity is admittedly important but what matters most to me is a splatter-free signal, and in that regard nothing comes close to what PS can produce. As I stated earlier, even the best Class A amplifiers only have -40dB splatter. PS starts at -60db and often pushes -70dB. That means that PS reduces splatter to less than 1% (and at times only 1/10 of 1%) of what even the best traditional equipment can produce.

I also agree with Simon that the 7300 (and also the 7610 for that matter) produces an extremely sharp-edged signal with unarguably less splatter than is achievable with any other non-ANAN radio. It was explained to me by Ray N5LAX that the reason those radios are so clean splatter-wise is because ICOM embedded an algorithm into the firmware that functions very similarly to PS in the sense that it corrects for non-linearity in the PA, but it is a fixed-value (i.e., static) correction only, not a real-time self-adjusting correction value such as is employed by PS. NOTE: I have not been able to verify that info, but that is what was told to me over-the-air by Ray when I commented that I had no idea how the 7300 could produce such a clean, sharp-edged signal. So I'm repeating it here.

IMO it's unwise and short-sighted to summarily dismiss the game-changing value that PS brings to the hobby. Its benefits are so unarguable that I (and Rob Sherwood) often wonder why the big-name radios don't offer it as a standard feature. It's free, so utilize it for goodness sake!

73,

Mark



 

 


Re: Open HPSDR Hermes (14 bit ADC, EP3C25) Transceiver Card

jdow
 

I suspect your specification is still beyond the state of the art. Is your transmitter that good?

It sounds like the 7300 is cleaner than average close in but has some issues fairly far out. That is a little surprising. I wonder if the "IP+" technology is simply RF feedback to linearize the transmitter stages such as is seen in the old Collins kW SSB amplifiers. I can see that having an issue that depends on the charteristics of the feedback loop. But those are strange characteristics.

I take it the noise peaks are broadband, right? Do they depend on the transmit frequency in any way? It sounds very much like there is a defect in a specific radio near you. Is that the case or are hams measuring this in general? If this affects all the 7300s then the FPGA code will probably have to be reworked to fix the bug. I kinda wish I had one and a nice lab with lots of pertinent test equipment. I doubt Keysight and ICOM would set me up to do it. (It'd be better for them to set up a tiger team of their engineers with the equipment needed to suppress this possible bug.)

{^_^}

On 20220225 01:55:45, Conrad, PA5Y wrote:

By clean I mean - can I hear anything of sufficient magnitude to disturb the noise floor anywhere in band, and hence inhibit my ability to receive signals close to the noise floor. The noise floor in a semi-rural location on 28, 50 and 70MHz is not particularly low so I do not feel that this is unreasonable. The biggest problem with the IC7300 is the AM noise bump at 20kHz and 130kHz which is only 60dB down on the carrier when running at 30W on 28MHz. This power level is typical when driving an amplifier.  When modulated with an SSB signal this occupies a considerable amount of bandwidth.  The close in PN -s only -120dBc/Hz at 1kHz and  -130dBc/Hz at 10kHz. The composite noise is -115kHz at 10kHz, this is not what I would consider clean, even close in. The K3S( and a few others) is far better in this respect although the PA has quite poor linearity, especially on 6m.

 

The Hermes will do a much better job with any decent PA, even without pure signal. There are some spurs @ -65dBc which improve with a higher sample rate.  I have not checked these with the V2 firmware but I will do immediately I receive my Hermes from Apache.

 

I do not think that a transceiver at the IC-7300 price point has fixed pre-distortion. As you quite correctly say keeping it under control over temperature and voltage variation would be difficult. Also Icom would almost certainly have mentioned it in their advertising. What the IC7300 does well is manage audio overshoots by using a ‘look ahead’ algorithm. This is maybe where the impression of it having a clean TX comes from.

 

I think that the problem here is that so many transceivers are quite bad, so I can just about accept that the IC-7300 is less bad.

 

73

 

Conrad PA5Y

 

From: main@SDR-Radio.groups.io <main@SDR-Radio.groups.io> On Behalf Of jdow via groups.io
Sent: 25 February 2022 10:27
To: main@SDR-Radio.groups.io
Subject: Re: [SDR-Radio] Open HPSDR Hermes (14 bit ADC, EP3C25) Transceiver Card

 

OK, please refresh my mind what you mean by "clean". It certainly appears to be sending something much closer to pure signal concentrated within its intended bandwidth than most other transmitters. I also understand that it is not as good as it can be with full active predistortion. Both might generate increased noise at some significant separation from the intended signal frequency. I am not sure of the mechanism by which this would take place.

As an ornery critter there is nothing I would sit down and declare "clean" without a definition of "clean". I guess I am asking for your definition of the term or even of the term "clean enough".

{O.O}

On 20220225 01:13:11, Conrad, PA5Y wrote:

I KNOW for a fact that the IC7300 is not clean. Please provide me some evidence to the contrary. I have measurements with a R&S FSWP Signal analyser out to a 1MHz BW. You guys are looking in an SSB BW which is fine unless you happen to be 130kHz away, then you will hear plenty of splatter from the IC7300. I tested the IC-7300 as a result of hearing this on 50MHz. In other words the lab tests were driven by on air experience.

 

You are spreading misleading and incorrect information.

 

73

 

Conrad PA5Y

 

From: main@SDR-Radio.groups.io <main@SDR-Radio.groups.io> On Behalf Of oldjackbob via groups.io
Sent: 24 February 2022 23:12
To:
main@SDR-Radio.groups.io
Subject: Re: [SDR-Radio] Open HPSDR Hermes (14 bit ADC, EP3C25) Transceiver Card

 

On Wed, Feb 23, 2022 at 12:24 PM, Max wrote:

I just think if we follow good design and signal chain management that superb, clean signals can also be generated without the need for PS, that's all.

Max,

I disagree. My signal is my signature. Audio clarity is admittedly important but what matters most to me is a splatter-free signal, and in that regard nothing comes close to what PS can produce. As I stated earlier, even the best Class A amplifiers only have -40dB splatter. PS starts at -60db and often pushes -70dB. That means that PS reduces splatter to less than 1% (and at times only 1/10 of 1%) of what even the best traditional equipment can produce.

I also agree with Simon that the 7300 (and also the 7610 for that matter) produces an extremely sharp-edged signal with unarguably less splatter than is achievable with any other non-ANAN radio. It was explained to me by Ray N5LAX that the reason those radios are so clean splatter-wise is because ICOM embedded an algorithm into the firmware that functions very similarly to PS in the sense that it corrects for non-linearity in the PA, but it is a fixed-value (i.e., static) correction only, not a real-time self-adjusting correction value such as is employed by PS. NOTE: I have not been able to verify that info, but that is what was told to me over-the-air by Ray when I commented that I had no idea how the 7300 could produce such a clean, sharp-edged signal. So I'm repeating it here.

IMO it's unwise and short-sighted to summarily dismiss the game-changing value that PS brings to the hobby. Its benefits are so unarguable that I (and Rob Sherwood) often wonder why the big-name radios don't offer it as a standard feature. It's free, so utilize it for goodness sake!

73,

Mark


 



Re: Open HPSDR Hermes (14 bit ADC, EP3C25) Transceiver Card

Simon Brown
 

Conrad,

 

80m SSB DXing has died as death – despite excellent conditions very few people coming on. Are you on 4m – if so I’ll be testing my new legal limit amplifier this afternoon.

 

Simon Brown, G4ELI

https://www.sdr-radio.com

 

From: main@SDR-Radio.groups.io <main@SDR-Radio.groups.io> On Behalf Of Conrad, PA5Y
Sent: 25 February 2022 10:28
To: main@SDR-Radio.groups.io
Subject: Re: [SDR-Radio] Open HPSDR Hermes (14 bit ADC, EP3C25) Transceiver Card

 

You are not painting an attractive picture Simon.

 

However when I get older and maintaining EME antennas gets too much for me.  I do always fancy 160 and 80m. Mainly because it appears to be challenging. I do plan to put up an EWE next winter just to get a feel for it. I’m not disinterested in the idea.

 

Conrad

 

From: main@SDR-Radio.groups.io <main@SDR-Radio.groups.io> On Behalf Of Simon Brown via groups.io
Sent: 25 February 2022 11:24
To: main@SDR-Radio.groups.io
Subject: Re: [SDR-Radio] Open HPSDR Hermes (14 bit ADC, EP3C25) Transceiver Card

 

Try listening in the 80m DX window in New England – AG1J uses a ~60 year-old SSB rig. Wide hardly starts to describe it, I think it’s a phasing exciter with obligatory after-burner.

 

Simon Brown, G4ELI

https://www.sdr-radio.com

 

From: main@SDR-Radio.groups.io <main@SDR-Radio.groups.io> On Behalf Of Conrad, PA5Y
Sent: 25 February 2022 09:56
To: main@SDR-Radio.groups.io
Subject: Re: [SDR-Radio] Open HPSDR Hermes (14 bit ADC, EP3C25) Transceiver Card

 

By clean I mean - can I hear anything of sufficient magnitude to disturb the noise floor anywhere in band, and hence inhibit my ability to receive signals close to the noise floor. The noise floor in a semi-rural location on 28, 50 and 70MHz is not particularly low so I do not feel that this is unreasonable. The biggest problem with the IC7300 is the AM noise bump at 20kHz and 130kHz which is only 60dB down on the carrier when running at 30W on 28MHz. This power level is typical when driving an amplifier.  When modulated with an SSB signal this occupies a considerable amount of bandwidth.  The close in PN -s only -120dBc/Hz at 1kHz and  -130dBc/Hz at 10kHz. The composite noise is -115kHz at 10kHz, this is not what I would consider clean, even close in. The K3S( and a few others) is far better in this respect although the PA has quite poor linearity, especially on 6m.

 

The Hermes will do a much better job with any decent PA, even without pure signal. There are some spurs @ -65dBc which improve with a higher sample rate.  I have not checked these with the V2 firmware but I will do immediately I receive my Hermes from Apache.

 

I do not think that a transceiver at the IC-7300 price point has fixed pre-distortion. As you quite correctly say keeping it under control over temperature and voltage variation would be difficult. Also Icom would almost certainly have mentioned it in their advertising. What the IC7300 does well is manage audio overshoots by using a ‘look ahead’ algorithm. This is maybe where the impression of it having a clean TX comes from.

 

I think that the problem here is that so many transceivers are quite bad, so I can just about accept that the IC-7300 is less bad.

 

73

 

Conrad PA5Y

 

From: main@SDR-Radio.groups.io <main@SDR-Radio.groups.io> On Behalf Of jdow via groups.io
Sent: 25 February 2022 10:27
To: main@SDR-Radio.groups.io
Subject: Re: [SDR-Radio] Open HPSDR Hermes (14 bit ADC, EP3C25) Transceiver Card

 

OK, please refresh my mind what you mean by "clean". It certainly appears to be sending something much closer to pure signal concentrated within its intended bandwidth than most other transmitters. I also understand that it is not as good as it can be with full active predistortion. Both might generate increased noise at some significant separation from the intended signal frequency. I am not sure of the mechanism by which this would take place.

As an ornery critter there is nothing I would sit down and declare "clean" without a definition of "clean". I guess I am asking for your definition of the term or even of the term "clean enough".

{O.O}

On 20220225 01:13:11, Conrad, PA5Y wrote:

I KNOW for a fact that the IC7300 is not clean. Please provide me some evidence to the contrary. I have measurements with a R&S FSWP Signal analyser out to a 1MHz BW. You guys are looking in an SSB BW which is fine unless you happen to be 130kHz away, then you will hear plenty of splatter from the IC7300. I tested the IC-7300 as a result of hearing this on 50MHz. In other words the lab tests were driven by on air experience.

 

You are spreading misleading and incorrect information.

 

73

 

Conrad PA5Y

 

From: main@SDR-Radio.groups.io <main@SDR-Radio.groups.io> On Behalf Of oldjackbob via groups.io
Sent: 24 February 2022 23:12
To:
main@SDR-Radio.groups.io
Subject: Re: [SDR-Radio] Open HPSDR Hermes (14 bit ADC, EP3C25) Transceiver Card

 

On Wed, Feb 23, 2022 at 12:24 PM, Max wrote:

I just think if we follow good design and signal chain management that superb, clean signals can also be generated without the need for PS, that's all.

Max,

I disagree. My signal is my signature. Audio clarity is admittedly important but what matters most to me is a splatter-free signal, and in that regard nothing comes close to what PS can produce. As I stated earlier, even the best Class A amplifiers only have -40dB splatter. PS starts at -60db and often pushes -70dB. That means that PS reduces splatter to less than 1% (and at times only 1/10 of 1%) of what even the best traditional equipment can produce.

I also agree with Simon that the 7300 (and also the 7610 for that matter) produces an extremely sharp-edged signal with unarguably less splatter than is achievable with any other non-ANAN radio. It was explained to me by Ray N5LAX that the reason those radios are so clean splatter-wise is because ICOM embedded an algorithm into the firmware that functions very similarly to PS in the sense that it corrects for non-linearity in the PA, but it is a fixed-value (i.e., static) correction only, not a real-time self-adjusting correction value such as is employed by PS. NOTE: I have not been able to verify that info, but that is what was told to me over-the-air by Ray when I commented that I had no idea how the 7300 could produce such a clean, sharp-edged signal. So I'm repeating it here.

IMO it's unwise and short-sighted to summarily dismiss the game-changing value that PS brings to the hobby. Its benefits are so unarguable that I (and Rob Sherwood) often wonder why the big-name radios don't offer it as a standard feature. It's free, so utilize it for goodness sake!

73,

Mark

 


--

- + - + -

Please use https://forum.sdr-radio.com:4499/ when posting questions or problems.


--
- + - + -
Please use https://forum.sdr-radio.com:4499/ when posting questions or problems.


Re: Open HPSDR Hermes (14 bit ADC, EP3C25) Transceiver Card

Conrad, PA5Y
 

You are not painting an attractive picture Simon.

 

However when I get older and maintaining EME antennas gets too much for me.  I do always fancy 160 and 80m. Mainly because it appears to be challenging. I do plan to put up an EWE next winter just to get a feel for it. I’m not disinterested in the idea.

 

Conrad

 

From: main@SDR-Radio.groups.io <main@SDR-Radio.groups.io> On Behalf Of Simon Brown via groups.io
Sent: 25 February 2022 11:24
To: main@SDR-Radio.groups.io
Subject: Re: [SDR-Radio] Open HPSDR Hermes (14 bit ADC, EP3C25) Transceiver Card

 

Try listening in the 80m DX window in New England – AG1J uses a ~60 year-old SSB rig. Wide hardly starts to describe it, I think it’s a phasing exciter with obligatory after-burner.

 

Simon Brown, G4ELI

https://www.sdr-radio.com

 

From: main@SDR-Radio.groups.io <main@SDR-Radio.groups.io> On Behalf Of Conrad, PA5Y
Sent: 25 February 2022 09:56
To: main@SDR-Radio.groups.io
Subject: Re: [SDR-Radio] Open HPSDR Hermes (14 bit ADC, EP3C25) Transceiver Card

 

By clean I mean - can I hear anything of sufficient magnitude to disturb the noise floor anywhere in band, and hence inhibit my ability to receive signals close to the noise floor. The noise floor in a semi-rural location on 28, 50 and 70MHz is not particularly low so I do not feel that this is unreasonable. The biggest problem with the IC7300 is the AM noise bump at 20kHz and 130kHz which is only 60dB down on the carrier when running at 30W on 28MHz. This power level is typical when driving an amplifier.  When modulated with an SSB signal this occupies a considerable amount of bandwidth.  The close in PN -s only -120dBc/Hz at 1kHz and  -130dBc/Hz at 10kHz. The composite noise is -115kHz at 10kHz, this is not what I would consider clean, even close in. The K3S( and a few others) is far better in this respect although the PA has quite poor linearity, especially on 6m.

 

The Hermes will do a much better job with any decent PA, even without pure signal. There are some spurs @ -65dBc which improve with a higher sample rate.  I have not checked these with the V2 firmware but I will do immediately I receive my Hermes from Apache.

 

I do not think that a transceiver at the IC-7300 price point has fixed pre-distortion. As you quite correctly say keeping it under control over temperature and voltage variation would be difficult. Also Icom would almost certainly have mentioned it in their advertising. What the IC7300 does well is manage audio overshoots by using a ‘look ahead’ algorithm. This is maybe where the impression of it having a clean TX comes from.

 

I think that the problem here is that so many transceivers are quite bad, so I can just about accept that the IC-7300 is less bad.

 

73

 

Conrad PA5Y

 

From: main@SDR-Radio.groups.io <main@SDR-Radio.groups.io> On Behalf Of jdow via groups.io
Sent: 25 February 2022 10:27
To: main@SDR-Radio.groups.io
Subject: Re: [SDR-Radio] Open HPSDR Hermes (14 bit ADC, EP3C25) Transceiver Card

 

OK, please refresh my mind what you mean by "clean". It certainly appears to be sending something much closer to pure signal concentrated within its intended bandwidth than most other transmitters. I also understand that it is not as good as it can be with full active predistortion. Both might generate increased noise at some significant separation from the intended signal frequency. I am not sure of the mechanism by which this would take place.

As an ornery critter there is nothing I would sit down and declare "clean" without a definition of "clean". I guess I am asking for your definition of the term or even of the term "clean enough".

{O.O}

On 20220225 01:13:11, Conrad, PA5Y wrote:

I KNOW for a fact that the IC7300 is not clean. Please provide me some evidence to the contrary. I have measurements with a R&S FSWP Signal analyser out to a 1MHz BW. You guys are looking in an SSB BW which is fine unless you happen to be 130kHz away, then you will hear plenty of splatter from the IC7300. I tested the IC-7300 as a result of hearing this on 50MHz. In other words the lab tests were driven by on air experience.

 

You are spreading misleading and incorrect information.

 

73

 

Conrad PA5Y

 

From: main@SDR-Radio.groups.io <main@SDR-Radio.groups.io> On Behalf Of oldjackbob via groups.io
Sent: 24 February 2022 23:12
To:
main@SDR-Radio.groups.io
Subject: Re: [SDR-Radio] Open HPSDR Hermes (14 bit ADC, EP3C25) Transceiver Card

 

On Wed, Feb 23, 2022 at 12:24 PM, Max wrote:

I just think if we follow good design and signal chain management that superb, clean signals can also be generated without the need for PS, that's all.

Max,

I disagree. My signal is my signature. Audio clarity is admittedly important but what matters most to me is a splatter-free signal, and in that regard nothing comes close to what PS can produce. As I stated earlier, even the best Class A amplifiers only have -40dB splatter. PS starts at -60db and often pushes -70dB. That means that PS reduces splatter to less than 1% (and at times only 1/10 of 1%) of what even the best traditional equipment can produce.

I also agree with Simon that the 7300 (and also the 7610 for that matter) produces an extremely sharp-edged signal with unarguably less splatter than is achievable with any other non-ANAN radio. It was explained to me by Ray N5LAX that the reason those radios are so clean splatter-wise is because ICOM embedded an algorithm into the firmware that functions very similarly to PS in the sense that it corrects for non-linearity in the PA, but it is a fixed-value (i.e., static) correction only, not a real-time self-adjusting correction value such as is employed by PS. NOTE: I have not been able to verify that info, but that is what was told to me over-the-air by Ray when I commented that I had no idea how the 7300 could produce such a clean, sharp-edged signal. So I'm repeating it here.

IMO it's unwise and short-sighted to summarily dismiss the game-changing value that PS brings to the hobby. Its benefits are so unarguable that I (and Rob Sherwood) often wonder why the big-name radios don't offer it as a standard feature. It's free, so utilize it for goodness sake!

73,

Mark

 


--

- + - + -

Please use https://forum.sdr-radio.com:4499/ when posting questions or problems.


Re: Open HPSDR Hermes (14 bit ADC, EP3C25) Transceiver Card

Conrad, PA5Y
 

When I get the opportunity I will check on 80m, I have not checked below 28MHz. On 80m I do not expect the composite noise to any issue due to the much higher noise floor on the low bands. So if you had mentioned 80m I would not have taken issue at all. However it is a multiband rig and on the higher bands it is not one of the cleanest rigs available. Far from it.

 

Regards

 

Conrad

 

From: main@SDR-Radio.groups.io <main@SDR-Radio.groups.io> On Behalf Of Simon Brown via groups.io
Sent: 25 February 2022 11:20
To: main@SDR-Radio.groups.io
Subject: Re: [SDR-Radio] Open HPSDR Hermes (14 bit ADC, EP3C25) Transceiver Card

 

Watching on-air on 80m and comparing to all other rigs people use.

 

Simon Brown, G4ELI

https://www.sdr-radio.com

 

From: main@SDR-Radio.groups.io <main@SDR-Radio.groups.io> On Behalf Of Conrad, PA5Y
Sent: 25 February 2022 09:13
To: main@SDR-Radio.groups.io
Subject: Re: [SDR-Radio] Open HPSDR Hermes (14 bit ADC, EP3C25) Transceiver Card

 

I KNOW for a fact that the IC7300 is not clean. Please provide me some evidence to the contrary. I have measurements with a R&S FSWP Signal analyser out to a 1MHz BW. You guys are looking in an SSB BW which is fine unless you happen to be 130kHz away, then you will hear plenty of splatter from the IC7300. I tested the IC-7300 as a result of hearing this on 50MHz. In other words the lab tests were driven by on air experience.

 

You are spreading misleading and incorrect information.

 

73

 

Conrad PA5Y

 

From: main@SDR-Radio.groups.io <main@SDR-Radio.groups.io> On Behalf Of oldjackbob via groups.io
Sent: 24 February 2022 23:12
To: main@SDR-Radio.groups.io
Subject: Re: [SDR-Radio] Open HPSDR Hermes (14 bit ADC, EP3C25) Transceiver Card

 

On Wed, Feb 23, 2022 at 12:24 PM, Max wrote:

I just think if we follow good design and signal chain management that superb, clean signals can also be generated without the need for PS, that's all.

Max,

I disagree. My signal is my signature. Audio clarity is admittedly important but what matters most to me is a splatter-free signal, and in that regard nothing comes close to what PS can produce. As I stated earlier, even the best Class A amplifiers only have -40dB splatter. PS starts at -60db and often pushes -70dB. That means that PS reduces splatter to less than 1% (and at times only 1/10 of 1%) of what even the best traditional equipment can produce.

I also agree with Simon that the 7300 (and also the 7610 for that matter) produces an extremely sharp-edged signal with unarguably less splatter than is achievable with any other non-ANAN radio. It was explained to me by Ray N5LAX that the reason those radios are so clean splatter-wise is because ICOM embedded an algorithm into the firmware that functions very similarly to PS in the sense that it corrects for non-linearity in the PA, but it is a fixed-value (i.e., static) correction only, not a real-time self-adjusting correction value such as is employed by PS. NOTE: I have not been able to verify that info, but that is what was told to me over-the-air by Ray when I commented that I had no idea how the 7300 could produce such a clean, sharp-edged signal. So I'm repeating it here.

IMO it's unwise and short-sighted to summarily dismiss the game-changing value that PS brings to the hobby. Its benefits are so unarguable that I (and Rob Sherwood) often wonder why the big-name radios don't offer it as a standard feature. It's free, so utilize it for goodness sake!

73,

Mark


--

- + - + -

Please use https://forum.sdr-radio.com:4499/ when posting questions or problems.


Re: Open HPSDR Hermes (14 bit ADC, EP3C25) Transceiver Card

Simon Brown
 

Try listening in the 80m DX window in New England – AG1J uses a ~60 year-old SSB rig. Wide hardly starts to describe it, I think it’s a phasing exciter with obligatory after-burner.

 

Simon Brown, G4ELI

https://www.sdr-radio.com

 

From: main@SDR-Radio.groups.io <main@SDR-Radio.groups.io> On Behalf Of Conrad, PA5Y
Sent: 25 February 2022 09:56
To: main@SDR-Radio.groups.io
Subject: Re: [SDR-Radio] Open HPSDR Hermes (14 bit ADC, EP3C25) Transceiver Card

 

By clean I mean - can I hear anything of sufficient magnitude to disturb the noise floor anywhere in band, and hence inhibit my ability to receive signals close to the noise floor. The noise floor in a semi-rural location on 28, 50 and 70MHz is not particularly low so I do not feel that this is unreasonable. The biggest problem with the IC7300 is the AM noise bump at 20kHz and 130kHz which is only 60dB down on the carrier when running at 30W on 28MHz. This power level is typical when driving an amplifier.  When modulated with an SSB signal this occupies a considerable amount of bandwidth.  The close in PN -s only -120dBc/Hz at 1kHz and  -130dBc/Hz at 10kHz. The composite noise is -115kHz at 10kHz, this is not what I would consider clean, even close in. The K3S( and a few others) is far better in this respect although the PA has quite poor linearity, especially on 6m.

 

The Hermes will do a much better job with any decent PA, even without pure signal. There are some spurs @ -65dBc which improve with a higher sample rate.  I have not checked these with the V2 firmware but I will do immediately I receive my Hermes from Apache.

 

I do not think that a transceiver at the IC-7300 price point has fixed pre-distortion. As you quite correctly say keeping it under control over temperature and voltage variation would be difficult. Also Icom would almost certainly have mentioned it in their advertising. What the IC7300 does well is manage audio overshoots by using a ‘look ahead’ algorithm. This is maybe where the impression of it having a clean TX comes from.

 

I think that the problem here is that so many transceivers are quite bad, so I can just about accept that the IC-7300 is less bad.

 

73

 

Conrad PA5Y

 

From: main@SDR-Radio.groups.io <main@SDR-Radio.groups.io> On Behalf Of jdow via groups.io
Sent: 25 February 2022 10:27
To: main@SDR-Radio.groups.io
Subject: Re: [SDR-Radio] Open HPSDR Hermes (14 bit ADC, EP3C25) Transceiver Card

 

OK, please refresh my mind what you mean by "clean". It certainly appears to be sending something much closer to pure signal concentrated within its intended bandwidth than most other transmitters. I also understand that it is not as good as it can be with full active predistortion. Both might generate increased noise at some significant separation from the intended signal frequency. I am not sure of the mechanism by which this would take place.

As an ornery critter there is nothing I would sit down and declare "clean" without a definition of "clean". I guess I am asking for your definition of the term or even of the term "clean enough".

{O.O}

On 20220225 01:13:11, Conrad, PA5Y wrote:

I KNOW for a fact that the IC7300 is not clean. Please provide me some evidence to the contrary. I have measurements with a R&S FSWP Signal analyser out to a 1MHz BW. You guys are looking in an SSB BW which is fine unless you happen to be 130kHz away, then you will hear plenty of splatter from the IC7300. I tested the IC-7300 as a result of hearing this on 50MHz. In other words the lab tests were driven by on air experience.

 

You are spreading misleading and incorrect information.

 

73

 

Conrad PA5Y

 

From: main@SDR-Radio.groups.io <main@SDR-Radio.groups.io> On Behalf Of oldjackbob via groups.io
Sent: 24 February 2022 23:12
To:
main@SDR-Radio.groups.io
Subject: Re: [SDR-Radio] Open HPSDR Hermes (14 bit ADC, EP3C25) Transceiver Card

 

On Wed, Feb 23, 2022 at 12:24 PM, Max wrote:

I just think if we follow good design and signal chain management that superb, clean signals can also be generated without the need for PS, that's all.

Max,

I disagree. My signal is my signature. Audio clarity is admittedly important but what matters most to me is a splatter-free signal, and in that regard nothing comes close to what PS can produce. As I stated earlier, even the best Class A amplifiers only have -40dB splatter. PS starts at -60db and often pushes -70dB. That means that PS reduces splatter to less than 1% (and at times only 1/10 of 1%) of what even the best traditional equipment can produce.

I also agree with Simon that the 7300 (and also the 7610 for that matter) produces an extremely sharp-edged signal with unarguably less splatter than is achievable with any other non-ANAN radio. It was explained to me by Ray N5LAX that the reason those radios are so clean splatter-wise is because ICOM embedded an algorithm into the firmware that functions very similarly to PS in the sense that it corrects for non-linearity in the PA, but it is a fixed-value (i.e., static) correction only, not a real-time self-adjusting correction value such as is employed by PS. NOTE: I have not been able to verify that info, but that is what was told to me over-the-air by Ray when I commented that I had no idea how the 7300 could produce such a clean, sharp-edged signal. So I'm repeating it here.

IMO it's unwise and short-sighted to summarily dismiss the game-changing value that PS brings to the hobby. Its benefits are so unarguable that I (and Rob Sherwood) often wonder why the big-name radios don't offer it as a standard feature. It's free, so utilize it for goodness sake!

73,

Mark

 


--
- + - + -
Please use https://forum.sdr-radio.com:4499/ when posting questions or problems.


Re: Open HPSDR Hermes (14 bit ADC, EP3C25) Transceiver Card

Simon Brown
 

Watching on-air on 80m and comparing to all other rigs people use.

 

Simon Brown, G4ELI

https://www.sdr-radio.com

 

From: main@SDR-Radio.groups.io <main@SDR-Radio.groups.io> On Behalf Of Conrad, PA5Y
Sent: 25 February 2022 09:13
To: main@SDR-Radio.groups.io
Subject: Re: [SDR-Radio] Open HPSDR Hermes (14 bit ADC, EP3C25) Transceiver Card

 

I KNOW for a fact that the IC7300 is not clean. Please provide me some evidence to the contrary. I have measurements with a R&S FSWP Signal analyser out to a 1MHz BW. You guys are looking in an SSB BW which is fine unless you happen to be 130kHz away, then you will hear plenty of splatter from the IC7300. I tested the IC-7300 as a result of hearing this on 50MHz. In other words the lab tests were driven by on air experience.

 

You are spreading misleading and incorrect information.

 

73

 

Conrad PA5Y

 

From: main@SDR-Radio.groups.io <main@SDR-Radio.groups.io> On Behalf Of oldjackbob via groups.io
Sent: 24 February 2022 23:12
To: main@SDR-Radio.groups.io
Subject: Re: [SDR-Radio] Open HPSDR Hermes (14 bit ADC, EP3C25) Transceiver Card

 

On Wed, Feb 23, 2022 at 12:24 PM, Max wrote:

I just think if we follow good design and signal chain management that superb, clean signals can also be generated without the need for PS, that's all.

Max,

I disagree. My signal is my signature. Audio clarity is admittedly important but what matters most to me is a splatter-free signal, and in that regard nothing comes close to what PS can produce. As I stated earlier, even the best Class A amplifiers only have -40dB splatter. PS starts at -60db and often pushes -70dB. That means that PS reduces splatter to less than 1% (and at times only 1/10 of 1%) of what even the best traditional equipment can produce.

I also agree with Simon that the 7300 (and also the 7610 for that matter) produces an extremely sharp-edged signal with unarguably less splatter than is achievable with any other non-ANAN radio. It was explained to me by Ray N5LAX that the reason those radios are so clean splatter-wise is because ICOM embedded an algorithm into the firmware that functions very similarly to PS in the sense that it corrects for non-linearity in the PA, but it is a fixed-value (i.e., static) correction only, not a real-time self-adjusting correction value such as is employed by PS. NOTE: I have not been able to verify that info, but that is what was told to me over-the-air by Ray when I commented that I had no idea how the 7300 could produce such a clean, sharp-edged signal. So I'm repeating it here.

IMO it's unwise and short-sighted to summarily dismiss the game-changing value that PS brings to the hobby. Its benefits are so unarguable that I (and Rob Sherwood) often wonder why the big-name radios don't offer it as a standard feature. It's free, so utilize it for goodness sake!

73,

Mark


--
- + - + -
Please use https://forum.sdr-radio.com:4499/ when posting questions or problems.


Re: Open HPSDR Hermes (14 bit ADC, EP3C25) Transceiver Card

Simon Brown
 

Been there, got very confused 😊 .

 

Simon Brown, G4ELI

https://www.sdr-radio.com

 

From: main@SDR-Radio.groups.io <main@SDR-Radio.groups.io> On Behalf Of jdow
Sent: 25 February 2022 08:52
To: main@SDR-Radio.groups.io
Subject: Re: [SDR-Radio] Open HPSDR Hermes (14 bit ADC, EP3C25) Transceiver Card

 

Military contracts fall into the code names and acronyms to the point whole conversations seem to exclusively use acronyms without normal nouns, verbs, and stuff. I'm glad I am out of that now.
{o.o}

On 20220225 00:39:44, sm6fhz wrote:

OK Simon.
I guess the filter tracking is generic to the HPSDR concept, let it be ANAN or Hermes.
Thanks for the info, good to know.
A name is just a name, is it an acronym for something? It might just be shorter to use a name rather than a full description.
The HPSDR crew seem to be very happy with naming the different parts. I have not been able to see any coupling between name and function on any of them.
Coming from the cellular base-station industry, I am fostered with acronyms for everything ;-) functions, products or projects, let it be that it looks like names and possible to pronounce :-)
Some of them needed a lot of fantasy and imagination to decode :-) and were created with the same amount of fantasy and imagination. LOF :-)
73 / Ingolf

 


--
- + - + -
Please use https://forum.sdr-radio.com:4499/ when posting questions or problems.


Re: Open HPSDR Hermes (14 bit ADC, EP3C25) Transceiver Card

Conrad, PA5Y
 

By clean I mean - can I hear anything of sufficient magnitude to disturb the noise floor anywhere in band, and hence inhibit my ability to receive signals close to the noise floor. The noise floor in a semi-rural location on 28, 50 and 70MHz is not particularly low so I do not feel that this is unreasonable. The biggest problem with the IC7300 is the AM noise bump at 20kHz and 130kHz which is only 60dB down on the carrier when running at 30W on 28MHz. This power level is typical when driving an amplifier.  When modulated with an SSB signal this occupies a considerable amount of bandwidth.  The close in PN -s only -120dBc/Hz at 1kHz and  -130dBc/Hz at 10kHz. The composite noise is -115kHz at 10kHz, this is not what I would consider clean, even close in. The K3S( and a few others) is far better in this respect although the PA has quite poor linearity, especially on 6m.

 

The Hermes will do a much better job with any decent PA, even without pure signal. There are some spurs @ -65dBc which improve with a higher sample rate.  I have not checked these with the V2 firmware but I will do immediately I receive my Hermes from Apache.

 

I do not think that a transceiver at the IC-7300 price point has fixed pre-distortion. As you quite correctly say keeping it under control over temperature and voltage variation would be difficult. Also Icom would almost certainly have mentioned it in their advertising. What the IC7300 does well is manage audio overshoots by using a ‘look ahead’ algorithm. This is maybe where the impression of it having a clean TX comes from.

 

I think that the problem here is that so many transceivers are quite bad, so I can just about accept that the IC-7300 is less bad.

 

73

 

Conrad PA5Y

 

From: main@SDR-Radio.groups.io <main@SDR-Radio.groups.io> On Behalf Of jdow via groups.io
Sent: 25 February 2022 10:27
To: main@SDR-Radio.groups.io
Subject: Re: [SDR-Radio] Open HPSDR Hermes (14 bit ADC, EP3C25) Transceiver Card

 

OK, please refresh my mind what you mean by "clean". It certainly appears to be sending something much closer to pure signal concentrated within its intended bandwidth than most other transmitters. I also understand that it is not as good as it can be with full active predistortion. Both might generate increased noise at some significant separation from the intended signal frequency. I am not sure of the mechanism by which this would take place.

As an ornery critter there is nothing I would sit down and declare "clean" without a definition of "clean". I guess I am asking for your definition of the term or even of the term "clean enough".

{O.O}

On 20220225 01:13:11, Conrad, PA5Y wrote:

I KNOW for a fact that the IC7300 is not clean. Please provide me some evidence to the contrary. I have measurements with a R&S FSWP Signal analyser out to a 1MHz BW. You guys are looking in an SSB BW which is fine unless you happen to be 130kHz away, then you will hear plenty of splatter from the IC7300. I tested the IC-7300 as a result of hearing this on 50MHz. In other words the lab tests were driven by on air experience.

 

You are spreading misleading and incorrect information.

 

73

 

Conrad PA5Y

 

From: main@SDR-Radio.groups.io <main@SDR-Radio.groups.io> On Behalf Of oldjackbob via groups.io
Sent: 24 February 2022 23:12
To:
main@SDR-Radio.groups.io
Subject: Re: [SDR-Radio] Open HPSDR Hermes (14 bit ADC, EP3C25) Transceiver Card

 

On Wed, Feb 23, 2022 at 12:24 PM, Max wrote:

I just think if we follow good design and signal chain management that superb, clean signals can also be generated without the need for PS, that's all.

Max,

I disagree. My signal is my signature. Audio clarity is admittedly important but what matters most to me is a splatter-free signal, and in that regard nothing comes close to what PS can produce. As I stated earlier, even the best Class A amplifiers only have -40dB splatter. PS starts at -60db and often pushes -70dB. That means that PS reduces splatter to less than 1% (and at times only 1/10 of 1%) of what even the best traditional equipment can produce.

I also agree with Simon that the 7300 (and also the 7610 for that matter) produces an extremely sharp-edged signal with unarguably less splatter than is achievable with any other non-ANAN radio. It was explained to me by Ray N5LAX that the reason those radios are so clean splatter-wise is because ICOM embedded an algorithm into the firmware that functions very similarly to PS in the sense that it corrects for non-linearity in the PA, but it is a fixed-value (i.e., static) correction only, not a real-time self-adjusting correction value such as is employed by PS. NOTE: I have not been able to verify that info, but that is what was told to me over-the-air by Ray when I commented that I had no idea how the 7300 could produce such a clean, sharp-edged signal. So I'm repeating it here.

IMO it's unwise and short-sighted to summarily dismiss the game-changing value that PS brings to the hobby. Its benefits are so unarguable that I (and Rob Sherwood) often wonder why the big-name radios don't offer it as a standard feature. It's free, so utilize it for goodness sake!

73,

Mark


 


Re: Open HPSDR Hermes (14 bit ADC, EP3C25) Transceiver Card

jdow
 

OK, please refresh my mind what you mean by "clean". It certainly appears to be sending something much closer to pure signal concentrated within its intended bandwidth than most other transmitters. I also understand that it is not as good as it can be with full active predistortion. Both might generate increased noise at some significant separation from the intended signal frequency. I am not sure of the mechanism by which this would take place.

As an ornery critter there is nothing I would sit down and declare "clean" without a definition of "clean". I guess I am asking for your definition of the term or even of the term "clean enough".

{O.O}

On 20220225 01:13:11, Conrad, PA5Y wrote:

I KNOW for a fact that the IC7300 is not clean. Please provide me some evidence to the contrary. I have measurements with a R&S FSWP Signal analyser out to a 1MHz BW. You guys are looking in an SSB BW which is fine unless you happen to be 130kHz away, then you will hear plenty of splatter from the IC7300. I tested the IC-7300 as a result of hearing this on 50MHz. In other words the lab tests were driven by on air experience.

 

You are spreading misleading and incorrect information.

 

73

 

Conrad PA5Y

 

From: main@SDR-Radio.groups.io <main@SDR-Radio.groups.io> On Behalf Of oldjackbob via groups.io
Sent: 24 February 2022 23:12
To: main@SDR-Radio.groups.io
Subject: Re: [SDR-Radio] Open HPSDR Hermes (14 bit ADC, EP3C25) Transceiver Card

 

On Wed, Feb 23, 2022 at 12:24 PM, Max wrote:

I just think if we follow good design and signal chain management that superb, clean signals can also be generated without the need for PS, that's all.

Max,

I disagree. My signal is my signature. Audio clarity is admittedly important but what matters most to me is a splatter-free signal, and in that regard nothing comes close to what PS can produce. As I stated earlier, even the best Class A amplifiers only have -40dB splatter. PS starts at -60db and often pushes -70dB. That means that PS reduces splatter to less than 1% (and at times only 1/10 of 1%) of what even the best traditional equipment can produce.

I also agree with Simon that the 7300 (and also the 7610 for that matter) produces an extremely sharp-edged signal with unarguably less splatter than is achievable with any other non-ANAN radio. It was explained to me by Ray N5LAX that the reason those radios are so clean splatter-wise is because ICOM embedded an algorithm into the firmware that functions very similarly to PS in the sense that it corrects for non-linearity in the PA, but it is a fixed-value (i.e., static) correction only, not a real-time self-adjusting correction value such as is employed by PS. NOTE: I have not been able to verify that info, but that is what was told to me over-the-air by Ray when I commented that I had no idea how the 7300 could produce such a clean, sharp-edged signal. So I'm repeating it here.

IMO it's unwise and short-sighted to summarily dismiss the game-changing value that PS brings to the hobby. Its benefits are so unarguable that I (and Rob Sherwood) often wonder why the big-name radios don't offer it as a standard feature. It's free, so utilize it for goodness sake!

73,

Mark



Re: Open HPSDR Hermes (14 bit ADC, EP3C25) Transceiver Card

jdow
 

I am not clear what you mean by "between the modulation".

The full feedback process for improving modulation characteristics attempts to make the transmitted signal as close to a perfect rendition of the ideal waveform as possible, This will probably reduce noise as well as signal distortion. It may even show a close to the carrier phase noise improvement depending on the design. When the SSB modulation goes silent the transmitter should go silent within the capabilities of the feedback loop. Outside the loop bandwidth there MIGHT be a small increase in the transmitter's noise floor.

With fixed predistortion (such as learning the precise D/A transfer function) the signal generation process is improved which will reduce IMD products and such. It may even allow for digitally compensating for the transmitter's linearity. This MAY need frequent calibration as it may be sensitive to supply voltages and the like. Temperature changes will almost assuredly alter the curves. But it will not make any material changes to the local oscillator noise characteristics.

I've noticed in the past that the average ham transceiver has nothing near the signal level to noise floor level characteristics of the receivers. That is largely a separate issue that will take some serious design efforts to change it. The goal of the whole exercise should be to make at least the next adjacent channel usable from a co-sited antenna with the transmitter running full power and as small a spacing between the two antennas as possible. There is a lot of room for effort here. And at present to my somewhat dated knowledge the transmitter is the most fertile ground for this effort at this time.

{^_^}

On 20220225 00:55:01, sm6fhz wrote:
Simon and Conrad.
It seems to me that you maybe are talking about two different parameters when it comes to a clean Tx-signal from the IC-7300.
I get that Simon is referring to splatter from the intended modulation.
I interpret that Conrad is looking at composite noise from a carrier.
I guess you are both correct.
If some kind of static Pre-Distortion is improving the the splatter levels from a SSB transmission it is very nice.
Still, the composite noise will be there in-between the modulation and also outside the modulation BW.
Splatter and composite noise will for sure have very different QRM characteristics on the band.
Can it be that the composite noise seen, is an artifact of the Pre-Distortion process?
Just a thought.....as I have never been deep diving into Pre-Distortion engineering. But usually there is a price to pay, if you are not very cautious with the details, when engineering a solution.
I am sure someone here is more into this and can explain.
73 / Ingolf, SM6FHZ


Re: Open HPSDR Hermes (14 bit ADC, EP3C25) Transceiver Card

Conrad, PA5Y
 

I KNOW for a fact that the IC7300 is not clean. Please provide me some evidence to the contrary. I have measurements with a R&S FSWP Signal analyser out to a 1MHz BW. You guys are looking in an SSB BW which is fine unless you happen to be 130kHz away, then you will hear plenty of splatter from the IC7300. I tested the IC-7300 as a result of hearing this on 50MHz. In other words the lab tests were driven by on air experience.

 

You are spreading misleading and incorrect information.

 

73

 

Conrad PA5Y

 

From: main@SDR-Radio.groups.io <main@SDR-Radio.groups.io> On Behalf Of oldjackbob via groups.io
Sent: 24 February 2022 23:12
To: main@SDR-Radio.groups.io
Subject: Re: [SDR-Radio] Open HPSDR Hermes (14 bit ADC, EP3C25) Transceiver Card

 

On Wed, Feb 23, 2022 at 12:24 PM, Max wrote:

I just think if we follow good design and signal chain management that superb, clean signals can also be generated without the need for PS, that's all.

Max,

I disagree. My signal is my signature. Audio clarity is admittedly important but what matters most to me is a splatter-free signal, and in that regard nothing comes close to what PS can produce. As I stated earlier, even the best Class A amplifiers only have -40dB splatter. PS starts at -60db and often pushes -70dB. That means that PS reduces splatter to less than 1% (and at times only 1/10 of 1%) of what even the best traditional equipment can produce.

I also agree with Simon that the 7300 (and also the 7610 for that matter) produces an extremely sharp-edged signal with unarguably less splatter than is achievable with any other non-ANAN radio. It was explained to me by Ray N5LAX that the reason those radios are so clean splatter-wise is because ICOM embedded an algorithm into the firmware that functions very similarly to PS in the sense that it corrects for non-linearity in the PA, but it is a fixed-value (i.e., static) correction only, not a real-time self-adjusting correction value such as is employed by PS. NOTE: I have not been able to verify that info, but that is what was told to me over-the-air by Ray when I commented that I had no idea how the 7300 could produce such a clean, sharp-edged signal. So I'm repeating it here.

IMO it's unwise and short-sighted to summarily dismiss the game-changing value that PS brings to the hobby. Its benefits are so unarguable that I (and Rob Sherwood) often wonder why the big-name radios don't offer it as a standard feature. It's free, so utilize it for goodness sake!

73,

Mark


Re: Open HPSDR Hermes (14 bit ADC, EP3C25) Transceiver Card

sm6fhz
 

Simon and Conrad.
It seems to me that you maybe are talking about two different parameters when it comes to a clean Tx-signal from the IC-7300.
I get that Simon is referring to splatter from the intended modulation.
I interpret that Conrad is looking at composite noise from a carrier.
I guess you are both correct.
If some kind of static Pre-Distortion is improving the the splatter levels from a SSB transmission it is very nice.
Still, the composite noise will be there in-between the modulation and also outside the modulation BW.
Splatter and composite noise will for sure have very different QRM characteristics on the band.
Can it be that the composite noise seen, is an artifact of the Pre-Distortion process?
Just a thought.....as I have never been deep diving into Pre-Distortion engineering. But usually there is a price to pay, if you are not very cautious with the details, when engineering a solution.
I am sure someone here is more into this and can explain.
73 / Ingolf, SM6FHZ

2401 - 2420 of 67963