Fw: [softrock40] 455khz IF and some VLF results.

Terry Fox wb4jfi at knology.net
Mon Sep 4 16:48:05 CDT 2006

If you guys are interested....

----- Original Message ----- 
From: picnet2 
To: softrock40 at yahoogroups.com 
Sent: Monday, September 04, 2006 5:13 PM
Subject: [softrock40] 455khz IF and some VLF results.

After rewinding L2 with 77 turns on a T50-1 core, softrock v6.1
with 1.8432 crystal (460.737 actual lo) and supply at 13.5v (drawing
around 20-30ma) I made some crude mds tests, using my "did the tone
just stop?" and "the waterfall monitor line just vanished" highly
scientific methods.

With M0KGK software, mds was around -125dbm at 455khz rx (thats
-125dbm on the generator rather than the software, which was
calibrated to -73dbm S9 and tracks rather nicely to +-0.5dbm the

set as divide by 4, 

For VLF - I saw another post on this topic?

at 100khz rx, (400khz on generator / external clock) mds was -61dbm
at 55khz rx, "audio" mds was around -47dbm e.g a signal of -47dbm was
needed to get any response (audio or change in spectral peak) 

Using winrad
at 55khz rx, at -72dbm the waterfall line / spectral peak was at noise
floor. (considering -73dbm is S9 the bandpass filter is doing its job)
although the sim gives -22dbm at 55khz for the bpf = 94dbm, which is
curiously too close to the soundcards theoretical 96db so maybe thats
what was being measured rather than any directly converted signal by
the softrock board?


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