[amsat-bb] What preamp to use for SO-50 and Arrow II antenna?

Paul Stoetzer n8hm at arrl.net
Fri May 1 04:00:12 UTC 2015

I use a High Sierra Microwave LNAA432 preamp powered by a 11.1v LiPo
battery pack (AAs or AAAs work fine too). I can work SO-50 down to the
horizon with the Arrow Antenna if I have a clear shot. I lost at about
a degree on the pass earlier. It's usually S1-2 below a couple of
degrees, S7 above 10 degrees, and my FT-817 shows S+ above 30 degrees
or so.

You have to be careful not to transmit into a receive only preamp like
this. I use two FT-817s, one for receive and one for transmit, so this
is not a problem for me, but if you use a single radio, you would need
to be sure that the preamp is between the 70cm antenna connection and
the diplexer so you don't fry it.


Paul, N8HM

On Thu, Apr 30, 2015 at 11:49 PM, John Brier <johnbrier at gmail.com> wrote:
> Since a lot of people are talking about SO-50 right now, let me ask a question:
> I did try to work SO-50 once when all I had ever worked before was
> SO-35, UO-14 and AO-27 and I was horrified by how hard it was to hear
> and track.
> I found a thread on qrz.com where they said it's very helpful to use a
> preamp for SO-50 since it's so low power, even with the short runs of
> coax required for an Arrow II satellite antenna. I know almost nothing
> about preamps. What's the deal? Do they need power to work
> (active/passive?). What do you recommend?
> John Brier, KG4AKV, Raleigh, NC, FM05
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