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Re: Modify the DEM 144-28DC Transverter



The MAR-6 has a noise figure a little under 3 dB. Since there is 20-30 dB of
gain ahead of this stage, reducing its noise figure by 2-2.5 dB will not
have a measurable effect  at 2400 MHz.

73,

John
KD6OZH
----- Original Message -----
From: "Alex Artieda HB9DRI" <hb9dri@artieda.net>
To: <amsat-bb@AMSAT.Org>
Sent: Monday, 10 September 2001 20:12 UTC
Subject: [amsat-bb] Modify the DEM 144-28DC Transverter


> Dear Friends:
>
> I have a question about the transverter DEM 144-28DC. I use this unit to
> convert the 144 (IF) output from my AO40 down converter MKU24 and feed my
HF
> radio on 28 Mhz, the DEM 144-28 Dc in the reception stage have an mmc
> circuit MAR-6 used like preamplifier on 144 Mhz and I want to know if is
> posible to improve the performance replacing this MAR-6 circuit for a
> premplifier with 20db gain and 0.6 NF, at 144 Mhz the MAR-6 have more or
> less same gain but 1.5 db NF. If I replace this preamp with less NF. the
> response for the down converter is better??? How much better??
>
> 73 DX
>
> Alex
> HB9DRI
>
>
> ----
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----
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