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Re: choice of IF frequencies



This can be done if you pick the IF frequencies so that the second and third
harmonics don't fall within any amateur band. The problem with using
existing amateur-band VHF/UHF transceivers is that amateur bands are
harmonicly related so heterodyning from 144 to 432 MHz or 432 to 1296 MHz
doesn't work well. Even 50 to 144 MHz and 222 to 432 MHz are problems if you
want full band coverage. So you must pick an IF frequency between amateur
bands like 180 or 360 MHz.

John
KD6OZH

----- Original Message -----
From: "Schaik, A. van" <avanschaik@hsl1.nl>
To: "'Achim Vollhardt'" <avollhar@physik.unizh.ch>; "'amsat-bb@amsat.org'"
<amsat-bb@AMSAT.Org>
Sent: Friday, 08 December 2000 10:17 UTC
Subject: RE: [amsat-bb] choice of IF frequencies


> Helo,
>
> With all this talk going on about IF frequenties it got me thinking (I
know
> its dangerus).
> Why not go for a more modular design like it's done for 3cm transverters.
> Separate every block like LO mixer frontend if filtering etc. if done
> corectly you can use any combination of tx and rx if with just one PA and
> frontend per band, 1 IF filter per IF  (both TX and RX), 2 mixers (1 for
TX
> and 1 or RX) and as many LO's as there are IF RF combinations.
> The only problem would be sheap switching.
>
> 73 de Andre PE1RDW
> aprsdigi co-ordinator Netherlands
> member aprs workgroup Netherlands
> mailto:pe1rdw@aprsnl.org
>
> ----
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