[amsat-bb] Re: New Preamp

scott wilson s.wilson at yahoo.com
Tue Sep 18 18:05:13 PDT 2007

> Hamtronics and they are still in business and do 
> offer a wide range of inexpensive preamps.
> See http://www.hamtronics.com/lnk.htm.

I have a couple of concerns about those preamps. They are probably fine
for portable/HT operation, but they may not be up to a permanent base
station application. The first concern would be with weather. If you
look at the SSB preamps, you'll see that they are enclosed in a
weatherproof case with the connectors facing downward, and are inside of
an RF sheilded case inside of that.

Second would be the power handling capabilities. Assuming that you don't
have a sequencer, they are going to probably receive your full transmit
power and need to be able to switch themselves. I don't see any mention
of a safe switching sense power, so they may assume you're using a

Third is that the power is being supplied over a non-shielded
connection. If the power run is longer than (short?), then you may pick
up some noise on it, which is then run straight into the box. The
preamps I have use a separate coax line for power since they're shielded
and since there's always some crappy RG-58 laying around.

A niggly concern are the BNC connections - Generally, they're used for
low power UHF signals, but most quality satellite oriented antennae use
N connectors - this will necessitate an adapter, but points to them
maybe being more appropriate for portable work.

Just my 0.02.



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