Hermes Lite RX
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Carlos Huerta
May 18, 2020, 9:43:48 PM5/18/20
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Interested in using the Hermes Lite between 1 to 500 Khz, is this board able to do this?
Thanks
Max
May 20, 2020, 10:38:42 AM5/20/20
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Hi Carlos
Spec says yes!
I am receiving perfectly on 198kHz in the UK (BBC Radio 4). I also clearly receive Rugby MSF on 60kHz and also Mainflingen in Germany on 77.5KHz.
Best
Max
Carlos Huerta
May 20, 2020, 12:10:09 PM5/20/20
to Max, Hermes-Lite
Thanks Max, great info, have you tried the gnu radio blocks for HL?
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Max
May 20, 2020, 12:39:48 PM5/20/20
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Hi Carlos
No, I don't have the time to experiment unfortunately. In any case, my main software for this radio is SDR Console. It works extremely well with HL2 for all my purposes:
Maybe I will get time to play with GNU Radio when I eventually retire, at about age 95 at the rate I am going!
Best
Max
On Wednesday, 20 May 2020 17:10:09 UTC+1, Carlos Huerta wrote:
Thanks Max, great info, have you tried the gnu radio blocks for HL?
Hi Carlos--Spec says yes!I am receiving perfectly on 198kHz in the UK (BBC Radio 4). I also clearly receive Rugby MSF on 60kHz and also Mainflingen in Germany on 77.5KHz.BestMax
On Tuesday, 19 May 2020 02:43:48 UTC+1, Carlos Huerta wrote:Interested in using the Hermes Lite between 1 to 500 Khz, is this board able to do this?Thanks
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in3otd
May 20, 2020, 3:31:24 PM5/20/20
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Hello,
just a clarification on the specs: the HW can be tuned down to "0 Hz" but the frequency response will be limited by the transformers and capacitors in the RF path.
I assume you are interested mainly in the RX, there the lowest frequency limit will be set mainly by the input transformer, T2, and the input capacitor B81; here you can find some measurements of different RX input transformer responses. I think that in practice the sensitivity at LF will depend on the SNR at the antenna, as the received noise will be high so the RX noise and sensitivity may not have a big impact but if you really need to go down to 1 kHz you may need to change the input circuitry, depending on your application.
73 de Claudio, DK1CG / IN3OTD
Steve Haynal
May 20, 2020, 5:49:20 PM5/20/20
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Hi Carlos,
I did a quick measurement with a loop back cable in full duplex mode: low power RF out connected to RX in through 30dB attenuator. Everything for TX and RX looked stable down to 150kHz. Low power out went down from 17dBm at 1.8MHz to 16dBm at 150kHz both via scope and RX measurements. Below 150kHz there were distortions in the TX (seen on my oscilloscope, so not indicative of problems with the RX), which may be due to the software and/or gateware and not the AD9866. The RX appears to still work, but again you might find issues with the software and/or gateware you are using at the lowest frequencies. As Claudio said, you may improve the low frequency performance by modifying TX and B81. We used to hand wind T2 on a larger core and you may need to do that again for best low frequency performance. The footprint for T2 actually has through holes to allow for easy mounting of this option.
73,
Steve
kf7o
Matthew
May 21, 2020, 6:59:58 AM5/21/20
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I don't really have much to add beyond what has already been said.
I have tried using my HL2 to listen to Grimeton SAQ . You get 2 (sometime 1) chances a year to test the setup! A stock HL2 wasn't good enough for me. I decided against modification of the HL2 and made a VLF transverter and after 5 years of (not very serious) experimenting trying to receive SAQ I copied the Christmas 2019 broadcast with my HL2+transverter.
I have used this with success in GNUradio with my HL2.
Good luck.
73 Matthew M5EVT.
On Wednesday, 20 May 2020 17:10:09 UTC+1, Carlos Huerta wrote:
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