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

Robert McGwier rwmcgwier at gmail.com
Tue Sep 4 02:49:31 PDT 2007


Tom Clark, K3IO wrote:
> 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.

CAN NOT BE more than an ohm.  I am sure the intent was clear but just 
wanted to make sure.

> 
> 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


-- 
AMSAT Director and VP Engineering. Member: ARRL, AMSAT-DL,
TAPR, Packrats, NJQRP, QRP ARCI, QCWA, FRC. ARRL SDR WG Chair
"If you're going to be crazy, you have to get paid for it or
else you're going to be locked up." Hunter S. Thompson


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