[Lowfer] analog vs sdr vlf/lf comparison

[JD]

Thanks for taking the time to read and address all those points, Doug.

I see from your reply that you do have the LPF in line for both units, so 
the test conditions are about as close as they can be for sensitivity and 
readability of difficult signals.  It's encouraging to learn that they 
perform so similarly.

On the frequency matter, it's not just the upconverter's stability that 
affects the outcome, but also the fact that the drift of a modern receiver 
(with its internal frequencies derived from one reference) is actually going 
to be a percentage error that applies to the tuned frequency.  Thus, my 
drift yesterday of 0.1 Hz out of 185,300 Hz would have been 1.7 Hz if I'd 
had to tune it in at 3,1853 MHz, even assuming no error at all from the 
upconverter.

If you ever have the time and inclination to try the test with both 
receivers tuned to 3.060 MHz at the output of the modified AMRAD converter, 
what that would really tell us is how both units do at HF, and thereby give 
a really great comparison of their natural stability.  A person could try 
that with both units tuned to WWV, of course, but I imagine the Doppler 
shift from the wandering ionosphere would result in a mighty thick Argo line 
at QRSS120.  Some days it's messy enough at QRSS3. :)

73
John