Topband: Re: topband RX

[dhaupt@bewellnet.com]

Actually, given the number of emails we have seen 
recently about flags, pennants, loops and other 
negative gain receive antennas, it is surprising 
that anybody would question using a sensitive 
receiver on 160 meters.  As W8JI points out, you 
can always put an attenuator inline with an 
overly-sensitive receiver, but there is nothing 
outboard that can be done to fix a poor IMD issue.

Given the RX antennas I'm going to be using, I'm 
actually going to have to add preamplifiers to 
them!

high level input mixers to sustain such a 
signals.  Pair of power MOSFET would
do but they are not commercially offered as a 
mixer...

Actually, you'd rather use a quartet of MOSFETS.  
There are some in the Motorola MRF line that are, 
I believe 30W RF power output capable with noise 
figure of 7 - 8 dB.  I always thought they'd make 
nice mixers, but other projects prevailed.

I always thought my IC-735 was a nice (but not 
great) radio until I started trying to listen to 
DX on 80 and 160.  It was nearly useless.  
Switched to using a Drake R-4B and suddenly I 
could hear.  The problem was PLL phase noise in 
the Icom.  Not fixable with external anythings.

Dave W8NF



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