Date   

Re: NDB - Airspy HF+ DIscovery versus Hermes Lite 2

jdow
 

I suspect you are not running them correctly.

I have listened to the best of the best analog. In fact I still have my R390A; but, it is retired just before I redesigned it for semiconductors. (I've been planning that for decades now. The earliest and most complete set of notes comes from the 1970s.) The basics of the designs for noise and dynamic range are basically the same. And the very basic detail that on large antennas attenuators on the receiver front and are an exceptionally good thing at MW and HF. Most SDRs have headaches from hitting their heads on their A/D's ceiling. The more bits of resolution (and precision) from their A/D converters helps. You may be suffering from a nearby large signal radio. For most (all) other front ends run the gain up until one of two things happens. The first thing, the good thing, is you reach a point where the signal to noise ratio does not improve. You can see that on the spectrum display. The second thing, the bad thing, is the display very suddenly shows a whole lot of signals you had not seen before. Go to a much higher gain and work down until these spurious signals become invisible. That's the best you'll get out of that front end.

For any AirSpy HF+ leave its internal AGC on. You lose the ability to calibrate it. But you get the best possible dynamic range that way.

Once you get good settings it should be as usable as any other radio for these frequencies and more usable than most because of digital only features.

{^_^}   (Poor thing. She only has 63 years experience and a couple college degrees as a result.)

On 20211223 07:38:34, Allan Isaacs wrote:

{o.o}

I have a couple of aerials, an 80m dipole and a random long wire about 150 feet long.

I use a matching unun with the long wire. The dipole works fine as a receiving aerial on any band and gives me the least local interference due to the feed point being very high and the ends clear of habitation.

I find all digital radios are inherently very noisy compared with old valve superhets.

I suppose most out there haven’t listened to a proper receiver with proper RF tuning and without a PLL.

There’s a challenge…

Allan G3PIY


From: main@SDR-Radio.groups.io [mailto:main@SDR-Radio.groups.io] On Behalf Of jdow
Sent: 23 December 2021 15:01
To: main@SDR-Radio.groups.io
Subject: Re: [SDR-Radio] NDB - Airspy HF+ DIscovery versus Hermes Lite 2

 

You have a really small antenna, perhaps? If not I suspect the Andrus is not setup as nicely as it could be. With a low loss antenna system below even 30 MHz and especially under 10 MHz it is VERY difficult to make a radio too insensitive to receive anything that is out there without reducing RF input gain by 10 dB to even 30 dB due to purely natural noise sources.



 



Re: NDB - Airspy HF+ Discovery versus Hermes Lite 2

Simon Brown
 

Max,

 

Do you connect the receive antenna direct or via a splitter? For a good test connect the receive antenna direct.

 

Simon Brown, G4ELI

https://www.sdr-radio.com

 

From: main@SDR-Radio.groups.io <main@SDR-Radio.groups.io> On Behalf Of Simon Brown
Sent: 24 December 2021 07:12
To: main@SDR-Radio.groups.io
Subject: Re: [SDR-Radio] NDB - Airspy HF+ Discovery versus Hermes Lite 2

 

Max,

 

Looking at this recording it would be interesting to see the Airspy settings (Ribbon Bar, Home). You could also try different Airspy bandwidths.

 

Simon Brown, G4ELI

https://www.sdr-radio.com

 

From: main@SDR-Radio.groups.io <main@SDR-Radio.groups.io> On Behalf Of Tom Seeger
Sent: 24 December 2021 01:34
To: main@SDR-Radio.groups.io
Subject: Re: [SDR-Radio] NDB - Airspy HF+ DIscovery versus Hermes Lite 2

 

Max, I do not need to do any of that with mine. I use HDSDR and just leave the AGC on auto, and the preamp OFF.  If you need to do all that then I would suggest there is something very wrong with your unit, or your driver, or perhaps the Airspy is being seriously overloaded by an out of band signal. On longwave mine is far superior to my WinRadio receiver, my ICOM, and SDRPlay. I'm not saying that it should be much better than your Hermes, but based on your videos, it should not be that much worse. 
Have you tried an LPF or even just a 10-20dB attenuator?
Tom


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Re: NDB - Airspy HF+ Discovery versus Hermes Lite 2

Simon Brown
 

Tom,

 

I’m surprised the Airspy is better than WinRadio on LF – what antenna do you use? Airspy is very sensitive, I expect WinRadio not as sensitive.

 

Simon Brown, G4ELI

https://www.sdr-radio.com

 

From: main@SDR-Radio.groups.io <main@SDR-Radio.groups.io> On Behalf Of Tom Seeger
Sent: 24 December 2021 01:34
To: main@SDR-Radio.groups.io
Subject: Re: [SDR-Radio] NDB - Airspy HF+ DIscovery versus Hermes Lite 2

 

Max, I do not need to do any of that with mine. I use HDSDR and just leave the AGC on auto, and the preamp OFF.  If you need to do all that then I would suggest there is something very wrong with your unit, or your driver, or perhaps the Airspy is being seriously overloaded by an out of band signal. On longwave mine is far superior to my WinRadio receiver, my ICOM, and SDRPlay. I'm not saying that it should be much better than your Hermes, but based on your videos, it should not be that much worse. 
Have you tried an LPF or even just a 10-20dB attenuator?
Tom


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


Re: NDB - Airspy HF+ Discovery versus Hermes Lite 2

Simon Brown
 

Max,

 

Looking at this recording it would be interesting to see the Airspy settings (Ribbon Bar, Home). You could also try different Airspy bandwidths.

 

Simon Brown, G4ELI

https://www.sdr-radio.com

 

From: main@SDR-Radio.groups.io <main@SDR-Radio.groups.io> On Behalf Of Tom Seeger
Sent: 24 December 2021 01:34
To: main@SDR-Radio.groups.io
Subject: Re: [SDR-Radio] NDB - Airspy HF+ DIscovery versus Hermes Lite 2

 

Max, I do not need to do any of that with mine. I use HDSDR and just leave the AGC on auto, and the preamp OFF.  If you need to do all that then I would suggest there is something very wrong with your unit, or your driver, or perhaps the Airspy is being seriously overloaded by an out of band signal. On longwave mine is far superior to my WinRadio receiver, my ICOM, and SDRPlay. I'm not saying that it should be much better than your Hermes, but based on your videos, it should not be that much worse. 
Have you tried an LPF or even just a 10-20dB attenuator?
Tom


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


Re: NDB - Airspy HF+ DIscovery versus Hermes Lite 2

Tom Seeger
 

Max, I do not need to do any of that with mine. I use HDSDR and just leave the AGC on auto, and the preamp OFF.  If you need to do all that then I would suggest there is something very wrong with your unit, or your driver, or perhaps the Airspy is being seriously overloaded by an out of band signal. On longwave mine is far superior to my WinRadio receiver, my ICOM, and SDRPlay. I'm not saying that it should be much better than your Hermes, but based on your videos, it should not be that much worse. 
Have you tried an LPF or even just a 10-20dB attenuator?
Tom


Re: NDB - Airspy HF+ DIscovery versus Hermes Lite 2

Max
 

Before I made the videos I spent quite a while on the Airspy tweaking all settings of AGC, then AGC off and multiple different gain settings. The recording I showed was the best result I could get. With the HL2 I just plugged it in, started it and tweaked nothing. Actually there are almost no controls to tweak anyway. Just LNA which is adjusted to prevent overload as per the front panel LEDs. In fact I don't remember the last time I needed to change that. Then there is just Visual Gain, which I usually adjust for -125dBm with no antenna connected. Admittedly I forgot to make the visual gain adjustment on the Airspy so that probably explains the HF+ looking very noisy. The background noise level with this setup is actually about S3 as you can see from the HL2 recording. For the Airspy I set sampling bandwidth to the minimum of 192kHz to give it the best chance. With the HL2, although I made the recording with sampling bandwidth set to 48kHz it gave identical results on all sampling bandwidths up to it's maximum of 384 kHz. No difference whatsoever.

So here's the question. Which is the better receiver? The one which anyone can just attach antenna, turn on and it just works perfectly with no issue or the one we need to make multiple excuses for this that or the other not being adjusted correctly?  I know which I'd rather have. Anyway, I did not set out to pick any faults with the Airspy. Why would I? I just paid good money for it! Just thought an interesting comparison given that the Airspy is always hailed as the "best thing since sliced bread" as we say here in the UK. It's just I was therefore quite surprised that the HL2 easily bettered it on the first test. I am sure there are other areas where the Airspy will outshine the HL2.

As I said before, I'm very interested to see results on 17.2 kHz tomorrow.

For info, I do have a local quite powerful AM station (about 8 miles away) and this certainly causes severe issues with my SDR Play RSP2Pro and I can also see signs of it being an issue that needs careful tweaking with the Airspy too (nothing like as bad as the RSP though). But it does not cause any issues whatsoever with the HL2. For me at least on the first few tests the HL2 is just considerably better on the frequencies it covers. Of course no VHF FM (for example) on the HL2 so it's horses for courses as ever.

Max


Re: NDB - Airspy HF+ DIscovery versus Hermes Lite 2

Gedas
 

You might be right but I would not assume that w/o verifying first.

Also, just for fun I made some amplitude measurements of my RSPdx. You might find the near end interesting. 73

https://www.youtube.com/watch?v=qHJE6wa9dVw

Gedas, W8BYA EN70JT

Gallery at http://w8bya.com
Light travels faster than sound....
This is why some people appear bright until you hear them speak.
On 12/23/2021 1:13 PM, Tom Seeger wrote:

I assume dBm. In any case its his Airspy vs my Airspy. So its relative and just for diagnostics.
73 Tom


Re: NDB - Airspy HF+ DIscovery versus Hermes Lite 2

Tom Seeger
 

I assume dBm. In any case its his Airspy vs my Airspy. So its relative and just for diagnostics.
73 Tom


Re: NDB - Airspy HF+ DIscovery versus Hermes Lite 2

Gedas
 

Tom, I do not own an Airspy so I do not know but when you say below -130 dB what are the units? dB what?

Are they an absolute figure like dBm (which is what you need) or is it a relative number related to ADU etc ?

Gedas, W8BYA EN70JT

Gallery at http://w8bya.com
Light travels faster than sound....
This is why some people appear bright until you hear them speak.
On 12/23/2021 11:15 AM, Tom Seeger wrote:

I wonder if you have both receivers connected to the antenna at the same time? This can cause digital noise emitted from one radio to be received by the other. Another good test is to disconnect the antenna from each radio and replace it with a 50 or 75 ohm resistor and record the base noise. It should be less than -130 dB. I measure about -135 dB on my HF Discovery at 277 kHz with a 250 Hz bandwidth. 
73 Tom


Re: A new way to shut off a PC

Simon Brown
 

David,

You get a message when booting about lack of power to the GPU.

Simon Brown, G4ELI
https://www.sdr-radio.com

-----Original Message-----
From: main@SDR-Radio.groups.io <main@SDR-Radio.groups.io> On Behalf Of David J Taylor via groups.io
Sent: 23 December 2021 13:48
To: main@SDR-Radio.groups.io
Subject: Re: [SDR-Radio] A new way to shut off a PC

On 23/12/2021 12:46, Tom Crosbie G6PZZ wrote:
Max et al,

I have a Corsair PSU too can’t recall exact model but it’s rated at
750W. It was overkill for the first PC I built with it and the second
and probably the third one too, built last year. My first with a
“good” graphics card. This PSU must be about 9 years old now and the
PC runs 24/7, current uptime about a year except for update reboots. I think I’m getting my money’s worth out of it.

Tom G6PZZ
Do some graphics cards have a second power supply connection? I've seen this with satellite TV tuner cards. Just wondering what might happen if the second power lead hadn't been connected....

David GM8ARV
--
SatSignal Software - Quality software for you
Web: https://www.satsignal.eu
Email: david-taylor@...
Twitter: @gm8arv









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


Re: NDB - Airspy HF+ DIscovery versus Hermes Lite 2

Tom Seeger
 

I wonder if you have both receivers connected to the antenna at the same time? This can cause digital noise emitted from one radio to be received by the other. Another good test is to disconnect the antenna from each radio and replace it with a 50 or 75 ohm resistor and record the base noise. It should be less than -130 dB. I measure about -135 dB on my HF Discovery at 277 kHz with a 250 Hz bandwidth. 
73 Tom


Re: NDB - Airspy HF+ DIscovery versus Hermes Lite 2

Allan Isaacs
 

{o.o}

I have a couple of aerials, an 80m dipole and a random long wire about 150 feet long.

I use a matching unun with the long wire. The dipole works fine as a receiving aerial on any band and gives me the least local interference due to the feed point being very high and the ends clear of habitation.

I find all digital radios are inherently very noisy compared with old valve superhets.

I suppose most out there haven’t listened to a proper receiver with proper RF tuning and without a PLL.

There’s a challenge…

Allan G3PIY


From: main@SDR-Radio.groups.io [mailto:main@SDR-Radio.groups.io] On Behalf Of jdow
Sent: 23 December 2021 15:01
To: main@SDR-Radio.groups.io
Subject: Re: [SDR-Radio] NDB - Airspy HF+ DIscovery versus Hermes Lite 2

 

You have a really small antenna, perhaps? If not I suspect the Andrus is not setup as nicely as it could be. With a low loss antenna system below even 30 MHz and especially under 10 MHz it is VERY difficult to make a radio too insensitive to receive anything that is out there without reducing RF input gain by 10 dB to even 30 dB due to purely natural noise sources.



 


Re: NDB - Airspy HF+ DIscovery versus Hermes Lite 2

Allan Isaacs
 

They’re easy enough to come by Tom.

This one belongs to the son of silent key G3PNV and has lain dormant for the best part of 50 years.

https://www.radiomuseum.co.uk/modR1155.html

Sacriligiously the dial is now a Muirhead but even smoother than the old type 35.

My first was bought from my English teacher for £3 (quite a lot of cash in those days when a good wage was £1 a day and suffice to say my parents hit the roof). Since then I acquired a few more with one coupled to a T1154.

All the best

Allan G3PIY

 


From: main@SDR-Radio.groups.io [mailto:main@SDR-Radio.groups.io] On Behalf Of Tom Crosbie G6PZZ
Sent: 23 December 2021 14:58
To: main@SDR-Radio.groups.io
Subject: Re: [SDR-Radio] NDB - Airspy HF+ DIscovery versus Hermes Lite 2

 

You lucky man Allan!

I almost had one around 1970. It sat at the back of the physics lab and someone had removed all the valves. Couldn’t afford them on pocket money. Never thought of hanging on to it until I started work and could afford it.

That tuning dial was really smooth.

 

Season’s greetings

 

Tom G6PZZ

 


Re: NDB - Airspy HF+ DIscovery versus Hermes Lite 2

Alan G4ZFQ
 

Unless I have a sub-par HF+? Wonder if you managed to watch my video recordings of the NDB?
Max,

I did. It seems the Airspy is excessively noisy. Levels appear to be high. I can not believe that a good Airspy could be that much worse.

What antenna? It could be that some out of band signal is causing the problem. Sometimes I use a LPF but that's not normally needed unless I TX.

73 Alan G4ZFQ


Re: NDB - Airspy HF+ DIscovery versus Hermes Lite 2

jdow
 

You have a really small antenna, perhaps? If not I suspect the Andrus is not setup as nicely as it could be. With a low loss antenna system below even 30 MHz and especially under 10 MHz it is VERY difficult to make a radio too insensitive to receive anything that is out there without reducing RF input gain by 10 dB to even 30 dB due to purely natural noise sources.

{o.o}

On 20211223 06:46:56, Allan Isaacs wrote:

Max.. I’m overhauling a WW2 R1155 and as I tuned across the long wave band a Polish station close to Radio 4 came in at a good S8 about mid day.

I checked on my Andrus SDR with the same aerial and it wasn’t more than a tiny spike with no audible modulation

Admittedly the R1155 has been modified with a 6AK5 RF stage…

Allan G3PIY


From: main@SDR-Radio.groups.io [mailto:main@SDR-Radio.groups.io] On Behalf Of Max
Sent: 23 December 2021 14:36
To: main@SDR-Radio.groups.io
Subject: Re: [SDR-Radio] NDB - Airspy HF+ DIscovery versus Hermes Lite 2

 

On Thu, Dec 23, 2021 at 12:34 PM, Patrick wrote:

It's indeed surprising.

As a LF enthusiast (chasing NDB for more than 20 years), I can tell the Discovery is one of the most sensitive receiver I have ever used

Hi Patrick

I don't think this shows any issue with the HF+ Discovery, just that the Hermes Lite 2 is a quite astonishing bit of kit for the money. Actually regardless of the cost. Punches way above its weight. I did always think so but this has just confirmed it for me. Unless I have a sub-par HF+? Wonder if you managed to watch my video recordings of the NDB?

Unfortunately I was not able to listen for Grimeton test transmissions today. Listening now but nothing heard so I guess too late to the game. I will be sure not to miss the main TX tomorrow morning.

Max



Re: NDB - Airspy HF+ DIscovery versus Hermes Lite 2

Tom Crosbie G6PZZ
 

You lucky man Allan!

I almost had one around 1970. It sat at the back of the physics lab and someone had removed all the valves. Couldn’t afford them on pocket money. Never thought of hanging on to it until I started work and could afford it.

That tuning dial was really smooth.

 

Season’s greetings

 

Tom G6PZZ

 

From: main@SDR-Radio.groups.io <main@SDR-Radio.groups.io> On Behalf Of Allan Isaacs
Sent: 23 December 2021 14:47
To: main@SDR-Radio.groups.io
Subject: Re: [SDR-Radio] NDB - Airspy HF+ DIscovery versus Hermes Lite 2

 

Max.. I’m overhauling a WW2 R1155 and as I tuned across the long wave band a Polish station close to Radio 4 came in at a good S8 about mid day.

I checked on my Andrus SDR with the same aerial and it wasn’t more than a tiny spike with no audible modulation

Admittedly the R1155 has been modified with a 6AK5 RF stage…

Allan G3PIY


From: main@SDR-Radio.groups.io [mailto:main@SDR-Radio.groups.io] On Behalf Of Max
Sent: 23 December 2021 14:36
To: main@SDR-Radio.groups.io
Subject: Re: [SDR-Radio] NDB - Airspy HF+ DIscovery versus Hermes Lite 2

 

On Thu, Dec 23, 2021 at 12:34 PM, Patrick wrote:

It's indeed surprising.

As a LF enthusiast (chasing NDB for more than 20 years), I can tell the Discovery is one of the most sensitive receiver I have ever used

Hi Patrick

I don't think this shows any issue with the HF+ Discovery, just that the Hermes Lite 2 is a quite astonishing bit of kit for the money. Actually regardless of the cost. Punches way above its weight. I did always think so but this has just confirmed it for me. Unless I have a sub-par HF+? Wonder if you managed to watch my video recordings of the NDB?

Unfortunately I was not able to listen for Grimeton test transmissions today. Listening now but nothing heard so I guess too late to the game. I will be sure not to miss the main TX tomorrow morning.

Max


Re: NDB - Airspy HF+ DIscovery versus Hermes Lite 2

jdow
 

One other thing - if he is not using the AirSpy HF+ Discovery's AGC he's very likely running with some gain mismatches in the analog portion of the chain.

{^_^}

On 20211223 06:36:19, Max wrote:
On Thu, Dec 23, 2021 at 12:34 PM, Patrick wrote:
It's indeed surprising.
As a LF enthusiast (chasing NDB for more than 20 years), I can tell the Discovery is one of the most sensitive receiver I have ever used
Hi Patrick

I don't think this shows any issue with the HF+ Discovery, just that the Hermes Lite 2 is a quite astonishing bit of kit for the money. Actually regardless of the cost. Punches way above its weight. I did always think so but this has just confirmed it for me. Unless I have a sub-par HF+? Wonder if you managed to watch my video recordings of the NDB?

Unfortunately I was not able to listen for Grimeton test transmissions today. Listening now but nothing heard so I guess too late to the game. I will be sure not to miss the main TX tomorrow morning.

Max


Re: NDB - Airspy HF+ DIscovery versus Hermes Lite 2

jdow
 

I suspect it is an issue with the antenna match to the receiver. One might provide better performance on any given antenna than the other. Which one does better depends on the antenna. And nothing says the better one cannot be improved upon with slight changes. This is down at a frequency range where antennas should not make any difference as far as QRM from outside the station's perimeter is concerned. But things such as wind can setup charges in wires it blows past. Front end impedance at DC can have significant effects on this. It might be entertaining, if the antenna is large (say a full size 80 meter dipole) to place an easily obtainable T connection and 50 ohm dummy load at the input of the receivers. If connecting the antenna raises the noise in both receivers the performance comparison should still face the same externally generated noise issue perhaps with less atmospheric effects differences on the antennas. The AirSpy's noise figure is do low that at any frequency under 10 MHz a 20 dB pad on a dipole antenna's feed line should not materially affect received SNR. So something else has to be creeping into the setup. Rain static? Wind effects? Really close by really high power AM radio station? That latter could exceed the AirSpy's dynamic range before it would affect something with an extra bit or two of A/D resolution. An AM band reject filter would mitigate this problem nicely. And it might improve both HL2 and AirSpy.

{^_^}

On 20211223 06:36:19, Max wrote:
On Thu, Dec 23, 2021 at 12:34 PM, Patrick wrote:
It's indeed surprising.
As a LF enthusiast (chasing NDB for more than 20 years), I can tell the Discovery is one of the most sensitive receiver I have ever used
Hi Patrick

I don't think this shows any issue with the HF+ Discovery, just that the Hermes Lite 2 is a quite astonishing bit of kit for the money. Actually regardless of the cost. Punches way above its weight. I did always think so but this has just confirmed it for me. Unless I have a sub-par HF+? Wonder if you managed to watch my video recordings of the NDB?

Unfortunately I was not able to listen for Grimeton test transmissions today. Listening now but nothing heard so I guess too late to the game. I will be sure not to miss the main TX tomorrow morning.

Max


Re: NDB - Airspy HF+ DIscovery versus Hermes Lite 2

Allan Isaacs
 

Max.. I’m overhauling a WW2 R1155 and as I tuned across the long wave band a Polish station close to Radio 4 came in at a good S8 about mid day.

I checked on my Andrus SDR with the same aerial and it wasn’t more than a tiny spike with no audible modulation

Admittedly the R1155 has been modified with a 6AK5 RF stage…

Allan G3PIY


From: main@SDR-Radio.groups.io [mailto:main@SDR-Radio.groups.io] On Behalf Of Max
Sent: 23 December 2021 14:36
To: main@SDR-Radio.groups.io
Subject: Re: [SDR-Radio] NDB - Airspy HF+ DIscovery versus Hermes Lite 2

 

On Thu, Dec 23, 2021 at 12:34 PM, Patrick wrote:

It's indeed surprising.

As a LF enthusiast (chasing NDB for more than 20 years), I can tell the Discovery is one of the most sensitive receiver I have ever used

Hi Patrick

I don't think this shows any issue with the HF+ Discovery, just that the Hermes Lite 2 is a quite astonishing bit of kit for the money. Actually regardless of the cost. Punches way above its weight. I did always think so but this has just confirmed it for me. Unless I have a sub-par HF+? Wonder if you managed to watch my video recordings of the NDB?

Unfortunately I was not able to listen for Grimeton test transmissions today. Listening now but nothing heard so I guess too late to the game. I will be sure not to miss the main TX tomorrow morning.

Max

_._,_._,_

 


Re: NDB - Airspy HF+ DIscovery versus Hermes Lite 2

Max
 

On Thu, Dec 23, 2021 at 12:34 PM, Patrick wrote:
It's indeed surprising.
As a LF enthusiast (chasing NDB for more than 20 years), I can tell the Discovery is one of the most sensitive receiver I have ever used
Hi Patrick

I don't think this shows any issue with the HF+ Discovery, just that the Hermes Lite 2 is a quite astonishing bit of kit for the money. Actually regardless of the cost. Punches way above its weight. I did always think so but this has just confirmed it for me. Unless I have a sub-par HF+? Wonder if you managed to watch my video recordings of the NDB?

Unfortunately I was not able to listen for Grimeton test transmissions today. Listening now but nothing heard so I guess too late to the game. I will be sure not to miss the main TX tomorrow morning.

Max

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