[Premium-Rx] Longwave Receiver Recommendations?

[George Georgevits]

Gentlemen,

What an excellent discussion on such an interesting topic! 

I have always been interested in VLF. I own a few of the receivers mentioned (Racal 6790GM, 6217 etc.) and have had fun fooling around with tuned loops and long wires. I can't say that any one receiver that I have used particularly excels. 

I recall talking to a  group of guys at a hamfest here in Australia a few years back. The name of their club escapes me, but their hobby was to have weekends away in the countryside with their LF radio gear. They would run around the paddocks, laying out miles of telephone jumper wire on the ground and then proceed to see how many overseas AM stations they could log. 

I am also the proud owner of a rather large boatanchor, the AWA CR3D, which I lovingly restored many years ago. It has two RF stages, a giant 12 position turret for the front end coils, tunes from 30MHz down to 14KHz and boasts 28 tubes.  It can vary the IF bandwidth by varying the coupling between each pair of IF coils using a ganged mechanical arrangement. Local AM stations sound really good at 15KHz bandwidth. If I was an engine driver, this Rx would be the equivalent of the 4-8-8-4 loco! See:

https://www.google.com/search?q=AWA+CR3D&tbm=isch&source=univ&client=firefox-b-d&sa=X&ved=2ahUKEwjxuvGW58voAhV97XMBHYenDt4QsAR6BAgHEAE

I found the discussion on ELF and Terry's article of particular interest. Given the lengths they had to go to (pun intended) to transmit the signal, I wonder what aerial the submarine used to receive it?  Surely not a very long wire towed in the water??? I also wonder what Rx equipment they used, that is, before the days of SDR? A quick search on the Internet drew a complete blank on this subject, even though the 76Hz system was decommissioned (and presumably declassified) in the early 2000's.

A very interesting discussion on the associated STANAG5030/MIL-188-140 and its modulation schemes can be found at:

http://i56578-swl.blogspot.com/search/label/STANAG-5030

and includes links to pages on associated topics.

Cheers,
George Georgevits 
VK2KGG

-----Original Message-----
From: premium-rx-bounces at mailman.qth.net [mailto:premium-rx-bounces at mailman.qth.net] On Behalf Of Terry O'
Sent: Friday, 3 April 2020 12:29 PM
To: premium-rx at mailman.qth.net
Subject: Re: [Premium-Rx] Longwave Receiver Recommendations?

The data rate was ridiculously slow.  3 characters in 15 minutes.  I 
wrote an article for Popular Communications on it, which, now they are 
out of print, is on my website.
http://blackradios.terryo.org/documents/publications/e-ELF.pdf

Terry O'


On 4/2/2020 8:14 PM, Jeremy Nichols wrote:
> Is that the receiver the Navy used with a transmitter somewhere in the
> upper Midwest? Michigan or Wisconsin? For communicating with subs under
> water anywhere in the world. Very low data rate.
>
> Jeremy
> N6WFO
>
>
>

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