[amsat-bb] Re: New Preamp
dguimon1 at san.rr.com
Tue Sep 18 22:12:40 PDT 2007
At 06:05 PM 9/18/2007, you wrote:
> > 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.
In over 25 years or so of using them, I've never had that concern..
1. I put them in a weather proof box.
2. I put in a type N connectors.
3. I ALWAYS use separate feed lines. To me separate feed lines,
spaced as far as physically possible is my answer to minimum
crosstalk.... And at 85 years old, I'm not about to, or attempt to
change my habits!!
4. I don't claim that is the way to do it, but it works for me....
Crappy RG-58 is never a part of anything in my system, and I have 19
holes in the wall of my house going to antennas, not all of them
always used, but I do a lot of experimenting.
73, Dave wb6llo at amsat.org
Disagree: I learn....
Pulling for P3E...
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