Re: [amsat-bb] A question about a MMIC preamp

["Frederick M. Spinner" <fspinner@xxxxxxxxxxx>]

Many EME'ers would have some heed to my comments on this, and they
would be right with huge gain huge F/B ratio antennas, but--

For terrestrial work, particularily in urban areas, the 2.8 dBNF of
a MAR-6 is less than the ambient noise of most QTH's at 144 MHz.  For 
satellite work with small low gain, low F/B antennas the terrestrial noise 
pickup is still quite a bit.

So a MAR-6 amplifier would work fine in your amp.  Try to figure some
way to have a DC ground at the input as I have had static problems with 
using it for a preamp before.

Alternatively, a cheap preamp kit would work too-- like Ramsey electronics 
or Hamtronics-- most are around 1 dB or less NF, and are
in the US$20 range..

Fred W0FMS



>From: Phil <phil@spiderweb.com.au>
>To: amsat-bb@AMSAT.Org
>Subject: [amsat-bb] A question about a MMIC preamp
>Date: Thu, 18 Oct 2001 10:41:54 +1000
>
>Hello all,
>
>In an effort to improve the reception of FO-20 and 29 I want to build a
>preamp.
>
>A preamp based on a Mini-Circuit's MMIC MAR-6 looks very appealing because 
>of
>the circuit's simplicity and minimal cost.
>
>My question is; are these devices suitable for weak satelite signal use or
>are they best relegated to commercial TV mast-head amplifiers? The gain is
>good, however, I'm wondering if the 3db noise figure might be a problem.
>
>--
>Regards,
>Phil
>phil@spiderweb.com.au
>----
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