[eagle] Re: Going into the deep Echo archives.

Tom Clark, K3IO tom.k3io at gmail.com
Mon Sep 3 22:19:43 PDT 2007


Bill Ress wrote:
> If I read the Excel spreadsheet correctly, if says that -100 dBm into 
> the SQRX at 28 Mhz was full quiting??? Is that directly into the coupler 
> you installed?
>   
Lyle should verify for sure, but I believe it is into the 2M whip's SMA
on the "top".
> Any idea what signal is needed at the 18" whip at 28 MHz to provide a 
> usable signal from the SQRX in the SSB mode? You know were I'm going 
> with this, don't you? Or have I lost the bubble here and that mode has 
> already been tried??
>   
Remember that the 18" whip is pretty short at 10M. The equivalent
circuit is a capacitor and a radiation resistance that can be more than
an ohm. So the sensitivity is quite low.

Yes, it has been tried in SSB (i.e. linear receiver), mostly for some
PSK31 tests. PSK31 signals (at whatever doppler is applicable) would
them modulate the NBFM xmtr. So you tune your favorite PSK31 demod on
the noise output from your 70cm rcvr. Downlink doppler is irrelevant.
Drew/Gould should offer comments, but I believe some signal were copied
by no QSOs made. The stations were (as I recall) running ~100 watts out
from a typical HF xcvr.

Again the problem is that the 18" whip is too short by a factor ~6.

Tom


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