NDB - Airspy HF+ DIscovery versus Hermes Lite 2


Max
 

On Sun, Jan 2, 2022 at 01:58 PM, sm6fhz wrote:
Hi Max.
This is what SAQ sounded like at my QTH.
Thanks for that Ingolf. Very nice recording. I guess not surprising that at just 43 km you can hear the alternator even when it is not being keyed!

73

Max


sm6fhz
 

Thanks :-)
I am using a 135 m terminated Beverage beaming in 310 degrees and a AFEDRI Net.
It is the antenna I use for MW DX for TA-stations. It beams into the Mid-west of the US.
I only have abt 43 km to the SAQ site. It is almost exactly in the back of the antenna.
You can hear / see the key up to key down ratio of SAQ quite clear in the recording. A lot of leakage :-)
73 / Ingolf


Simon Brown
 

Very nice 😊 – what’s the antenna?

 

 

Simon Brown, G4ELI

https://www.sdr-radio.com

 

From: main@SDR-Radio.groups.io <main@SDR-Radio.groups.io> On Behalf Of sm6fhz
Sent: 02 January 2022 13:58
To: main@SDR-Radio.groups.io
Subject: Re: [SDR-Radio] NDB - Airspy HF+ DIscovery versus Hermes Lite 2

 

Hi Max.
This is what SAQ sounded like at my QTH.
1 MB IQ-recording attached. Play with SDRconsole.
73 / Ingolf, SM6FHZ


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


sm6fhz
 

Hi Max.
This is what SAQ sounded like at my QTH.
1 MB IQ-recording attached. Play with SDRconsole.
73 / Ingolf, SM6FHZ


sm6fhz
 

Hi Max.
CHT is audible here right now, December 28, 2159 UTC.  QRB 1029 km.
I am using a AFEDRI Net and a 80 m terminated Beverage antenna beaming in 250 degrees.
It is NOT audible on the 135 m terminated Beverage beaming 310 degrees.
73 / Ingolf, SM6FHZ


jdow
 

Likely that would be antenna impedance variation and over exuberance for the matching transformer.

{^_^}

On 20211227 09:20:58, Max wrote:

On Mon, Dec 27, 2021 at 10:28 AM, Max wrote:
On Sun, Dec 26, 2021 at 03:24 PM, sm6fhz wrote:
If you missed the SAQ transmission on December 24th you have a new opportunity on December 27th
Thanks Ingolf. Only just seen this so listening.

Eventually heard SAQ this morning. Two video recordings linked for anyone who is at all interested. First one shows "VVV de SAQ" test signal from SAQ. Second one they were presumably trying to optimise antennas as it's just carrier (note the alternator drift!).

For those that wanted to see (Simon), ribbon bar in second video shows the HF+ settings. For Joanne I made sure to engage AGC as requested. Tried both settings (see second video), and also you will see preamp on and preamp off. Not much change. Antenna 66ft end fed wire, so far from ideal at this frequency. With a well matched antenna I'm sure results would have been far better.

Videos:

SAQ "VVV test"

SAQ Carrier

As per 24th compared with HL2 and RSP2Pro. Results exactly the same. Zero on HL2 (as predicted - below published frequency spec for unmodified unit) and on RSP2Pro, audible but not really readable (with juggled settings).

Yes, as per comments, both for 24th and today, antenna always connected direct, no splitter (I have not got one).

So again in this test 17.2 kHz the Airspy triumphed but at 277 kHz CHT NDB I've gone back and retested and consistently and possibly surprisingly the Hermes Lite is the winner over the HF+ by quite a margin. Next I need to test with better optimised LF antenna (loop?) and see if the disparity still exists. I still really like the tiny Airspy, and of course I adore my HL2. Both brilliant bits of kit for very little money. We are very lucky people to have such hardware available to us and of course goes without saying would not be possible without the likes of Simon's superb SDR Console. There's none better!

Max


Max
 

On Mon, Dec 27, 2021 at 05:20 PM, Max wrote:
For Joanne I made sure to engage AGC as requested. Tried both settings (see second video)
Just realised in second video in my last post it looks like when I turned on the AGC "Hi" position the signal disappeared, but just bad timing. It made no or little difference wen the signal was there.

Max


Max
 

On Mon, Dec 27, 2021 at 10:28 AM, Max wrote:
On Sun, Dec 26, 2021 at 03:24 PM, sm6fhz wrote:
If you missed the SAQ transmission on December 24th you have a new opportunity on December 27th
Thanks Ingolf. Only just seen this so listening.

Eventually heard SAQ this morning. Two video recordings linked for anyone who is at all interested. First one shows "VVV de SAQ" test signal from SAQ. Second one they were presumably trying to optimise antennas as it's just carrier (note the alternator drift!).

For those that wanted to see (Simon), ribbon bar in second video shows the HF+ settings. For Joanne I made sure to engage AGC as requested. Tried both settings (see second video), and also you will see preamp on and preamp off. Not much change. Antenna 66ft end fed wire, so far from ideal at this frequency. With a well matched antenna I'm sure results would have been far better.

Videos:

SAQ "VVV test"

SAQ Carrier

As per 24th compared with HL2 and RSP2Pro. Results exactly the same. Zero on HL2 (as predicted - below published frequency spec for unmodified unit) and on RSP2Pro, audible but not really readable (with juggled settings).

Yes, as per comments, both for 24th and today, antenna always connected direct, no splitter (I have not got one).

So again in this test 17.2 kHz the Airspy triumphed but at 277 kHz CHT NDB I've gone back and retested and consistently and possibly surprisingly the Hermes Lite is the winner over the HF+ by quite a margin. Next I need to test with better optimised LF antenna (loop?) and see if the disparity still exists. I still really like the tiny Airspy, and of course I adore my HL2. Both brilliant bits of kit for very little money. We are very lucky people to have such hardware available to us and of course goes without saying would not be possible without the likes of Simon's superb SDR Console. There's none better!

Max


Max
 

On Sun, Dec 26, 2021 at 03:24 PM, sm6fhz wrote:
If you missed the SAQ transmission on December 24th you have a new opportunity on December 27th
Thanks Ingolf. Only just seen this so listening.

Brief update as short on time over the break but I did listen for SAQ on the 24th on HF+ DIscovery, Hermes Lite 2 and SDR Play RSP2Pro. I have two wires, 132ft but this currently has a 49:1 Unun in it which I intend eventually to be able to bypass but as expected is most likely choking off the signal or at least badly optimised, so the best signal from SAQ was actually on my other wire which is a much lower 66ft end fed. Again, poorly optimised, but it did pull in a signal. Not great, but audible. 

Sorry, not a very scientific report, but basically the result was that the best reception of SAQ was on the HF+ confirming my suspicion that the HL2 is not optimised for VLF reception (which is actually documented and expected but can be changed if required).

The signal from SAQ did not seem as strong as I have received previously (as documented by some other listeners on the YouTube channel live chat).

On RSP2Pro the signal was audible but not readable (LF/wire antenna input). On the HF+ it was just readable (signal report RST 479) and on the HL2 nothing heard at all. So at this frequency the HF+ won out by quite a margin. So will probably keep it even if just for VLF and also for just sheer portability. Still shocked and amazed at how amazingly small it is. I will most likely set up something like a Wellgood or Miniwhip to leave permanently connected to the HF+ with some sort of front end diode limiter to protect the front end when transmitting.

Max


sm6fhz
 

Hi all!
If you missed the SAQ transmission on December 24th you have a new opportunity on December 27th:

https://alexander.n.se/saq-is-testing-on-december-27th/

Good luck and enjoy!

73 / Ingolf, SM6FHZ


Allan Isaacs
 

Sorry you lost your beam YL. It must have been a really traumatic experience.

I did buy a box of dual gate mosfets many moons ago with the aim of transistorising my R206. I got as far as changing the EF50 oscillator and eliminated oscillator pulling when using it with a nuvistor converter on 2m but reverted to a valve when overcome with guilt but I admit to leaving in place the tiny FM TDA chip for 2m as it was so small to be almost unnoticeable.

 

The goodish news is I just repaired a broken earth lead that a visitor had tripped over. This connects to the unun and I can now report the LW Polish station on 225KHz has shot up from -92dBm to -75dBm and is now intelligible on the Andrus SDR. In fact I counted eight AM LW broadcast stations. Radio 4 went from -47dBm to -32.5dBm and I had to insert 20dB attenuation to eliminate spurii.

 

I met my very understanding wife G3SGL on 80m SSB back in the 60s.

Allan G3PIY


From: main@SDR-Radio.groups.io [mailto:main@SDR-Radio.groups.io] On Behalf Of jdow
Sent: 24 December 2021 10:53
To: main@SDR-Radio.groups.io
Subject: Re: [SDR-Radio] NDB - Airspy HF+ DIscovery versus Hermes Lite 2

 

Heh, me be injuneer. Alas not hairy chested for some reason. So MY R390A has been tweaked a little. It goes down into that frequency range. I used it a little. I moved back to 20 meters SSB talking with folks in Oz after dinner here. (nice folks.) At that time I had a TH6DXX at 70'. Gone with the divorce. And I still think I won.

I also built in a hang AGC system and rewired the demodulation processes so that for SSB and CW I used a 7360 tube.  Heaven forbid you'd think I'd leave it unmodified. Hm, I also had a nice vernier knob on it. I forget the exact ratio. I get something like 2 kHz to 5 kHz per revolution. It has an PLL synchronous AM demodulator that I'm not fond of. It needs tweaking and was not worth it. Its a superb SSB receiver. I used it in actual communications service rather than SWL.

{o.o}


jdow
 

Heh, me be injuneer. Alas not hairy chested for some reason. So MY R390A has been tweaked a little. It goes down into that frequency range. I used it a little. I moved back to 20 meters SSB talking with folks in Oz after dinner here. (nice folks.) At that time I had a TH6DXX at 70'. Gone with the divorce. And I still think I won.

I also built in a hang AGC system and rewired the demodulation processes so that for SSB and CW I used a 7360 tube.  Heaven forbid you'd think I'd leave it unmodified. Hm, I also had a nice vernier knob on it. I forget the exact ratio. I get something like 2 kHz to 5 kHz per revolution. It has an PLL synchronous AM demodulator that I'm not fond of. It needs tweaking and was not worth it. Its a superb SSB receiver. I used it in actual communications service rather than SWL.

{o.o}

On 20211224 02:01:22, Allan Isaacs wrote:

The R390A is one I still need to try out. It is somewhat of a lightweight pound for pound though compared with say the DST100 which tunes down to 50KHz and uses a VP41 RF amplifier to handle 10V RMS signals without distortion or so they claim. Is this the ultimate valve receiver I wonder, although for VLF maybe the CJD wins.

Alas mine is yet persuaded to work so I cannot tell.

Allan G3PIY


From: main@SDR-Radio.groups.io [mailto:main@SDR-Radio.groups.io] On Behalf Of jdow
Sent: 24 December 2021 08:07
To: main@SDR-Radio.groups.io
Subject: Re: [SDR-Radio] NDB - Airspy HF+ DIscovery versus Hermes Lite 2

 

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.)

 



Allan Isaacs
 

The R390A is one I still need to try out. It is somewhat of a lightweight pound for pound though compared with say the DST100 which tunes down to 50KHz and uses a VP41 RF amplifier to handle 10V RMS signals without distortion or so they claim. Is this the ultimate valve receiver I wonder, although for VLF maybe the CJD wins.

Alas mine is yet persuaded to work so I cannot tell.

Allan G3PIY


From: main@SDR-Radio.groups.io [mailto:main@SDR-Radio.groups.io] On Behalf Of jdow
Sent: 24 December 2021 08:07
To: main@SDR-Radio.groups.io
Subject: Re: [SDR-Radio] NDB - Airspy HF+ DIscovery versus Hermes Lite 2

 

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.)

 


jdow
 

Assume dB relative to full scale for the A/D converter.
{^_^}

On 20211223 10:13:42, Tom Seeger wrote:

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


jdow
 

Exactly dB what. They are a measure of how far down you are from when the front end overloads. With the AirSpy HF+ further calibration is not really possible last I knew. For most other front ends calibration is possible and remarkably accurate and linear.

{^_^}

On 20211223 09:41:40, Gedas wrote:

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


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.



 



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


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


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


Tom Seeger
 

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