Topband: Re: diversity rx

[N7wb at aol.com]

In a message dated 6/2/2004 4:23:50 PM US Mountain Standard Time, 
r390a at bellsouth.net writes:
diversity
systems out there using the R-390/390A that were just *for*
that. Dual diversity was used with the GRC-26, GRC-129, FRR-3,
FRR-33, 38, 39,41 and others. The FRR-34 used *three* R-390's
for triple diversity
Also the Collins TRC-90B (I think I recall the right Army ID #) troposcatter 
gear used "dual diversity reception." This was 4.4 to 5.0 GHz at 1,000 watts 
aimed at the horizon in the direction of the distant station. There were two 
dishes, one for receive only and the other was XMIT and RECV. I recall watching 
the IF signal levels on the stations in Vietnam on the two receivers. I think 
that if one fell below about -50 dB, the other would switch in. I think there 
was at times as much as 20 or 30 dB difference between the receivers depending 
on the WX/conditions between the stations.

Antennas were spaced a couple dish diameters maybe, so there was possibly 
believed to be an optimum separation. I don't think there were polarization 
differences between the two dishes.

Not top band frequencies but the principles were possibly the same.

73 de John N7WB