[Boatanchors] Available Tube VLF Rcvrs

[Al Klase]

OK, I'm going to "pile on" with a while-we're-on-the-subject post.

The antenna is the critical link, but it doesn't have to be elaborate.  
A small loop will work much better that all but the most elaborate wire 
antennas.  Even a low-Q broadly-tuned loop is useful.  Google 
"octoloop."  You want to get down to hearing "spherics" (lightning 
crashes) rather than buzzing.

There are a lot of stations down there that can only be identified by 
their frequency and type of modulation.  For example, the VLF 
"submarine" stations, like super-loud NAA on 24 KHz, are just Gaussian 
lumps of encrypted white noise.  A sideband receiver feeding audio 
spectrum analyzer software on your PC can provide a lot of 
entertainment.  I'm blessed with a W-J 357 w/Nixie readout, but a simple 
crystal-controlled VLF converter in front to a rice box would be my next 
choice.

If I were going to use a vintage receiver, like an RBA, RAK, etc., I'd 
set a signal generator and frequency counter beside it to sort things out.

Your first targets beyond local NDB's:

100KHz:   Loud wide-band rattle of Loran-C pulses.  I've heard this on a 
crystal set here in New Jersey.
60KHz:    WWVB - Steady CW carrier is reduced by 10dB at a one hertz 
rate to convey time-code info.  Your wrist watch hears this in the 
middle of the night.
24KHz      MSK a la NAA (see above,)

Have fun,
Al

-- 
Al Klase - N3FRQ
Jersey City, NJ
http://www.skywaves.ar88.net/