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Re: Preamp recommendations



I have Mirage preamps for 2 meters and 70 cm.  The 70 cm preamp has been on
the mast for almost 5 years providing good service.  Although by no means
necessary, FO-20 and FO-29 contacts are more pleasurable with a preamp in
place.  The 2 meter preamp has spent more time off my mast than on over the
last 5 years.  I have replaced the 2 meter power block (the device that
sends 12v dc up the coax to the mast mounted preamp) twice and it needs
fixed or replaced again.  It keeps burning up.  Although my swr readings
don't indicate it, there must be a short somewhere on the 2 meter side.  I
certainly wish I had the 2 meter preamp operating for AO-10 because contacts
on this satellite for me are a challenge.

I use Belden 9913 coax with KLM 2 meter (22 el) and 70 cm (14 el) circular
polarized antennas and a Yeasu FT847.

Kevin Smith
N3HKQ
FN00be

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----- Original Message -----
From: <markw@instantdocuments.com>
To: <amsat-bb@AMSAT.Org>
Sent: Thursday, July 01, 1999 3:56 PM
Subject: [amsat-bb] Preamp recommendations


> I'm sure it has been answered before, but I have have not seen it so:
>
> I'm looking for a really good preamp for 70cm, the best available. That is
> of course if I do indeed need one at all. My modus iperandi is to pretty
> much
> get the best available up front, so I don't care if it is expensive or if
it
> will
> only give me 'a little' benefit. The preamp needs to switch between TX and
> RX,
> I do not mind running a PTT signal wire to the preamp, which will be
mounted
> on the antenna.
>
> I'm setting up to work 1200 and 9600 baud satellites. I'm getting some M2
> circular beams in any day now. I'm using Time Microwave LMR  600 cable,
> which is pretty good stuff, with very low loss. This goes to a Yaesu
FT847,
> I don't know much about the noise figure of the built in 'pre-amp'.
>
> Question 1: Will a preamp help at all? One book says I MUST have preamps,
> another says I don't need them. Lots of opinions. Does anyone have yet
more
> opinions, if so I would like to hear them.
>
> Question 2: Is there a preamp FAQ out there?
>
> Question 3: If you are using preamps, what is your favorite brand/model?
>
> So far it looks like the SSB SP-7000 is the one to beat. It claims 10-20dB
> with a maximum Noise figure of 0.9db. Others are publishing better noise
> numbers
> but do not provide curves like SSB does. Also SSB is using single gate
> GaAsFets,
> which I undestand are quieter than dual gate GaAsFets, and MUCH quieter
than
> bipolars (which realy are'nt under consideration anyway).
>
> - Mark West
>
>
>
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