[amsat-bb] RE: MicroWave: 1296 Transverter design advice

["Dave Metz" <Dave.Metz@xxxxxxxxxxxxxxxxx>]

> From:          "David Robinson" <robinda@nortelnetworks.com>
> To:            "'Dave Metz'" <davemetz@muscanet.com>
> Subject:       RE: MicroWave: 1296 Transverter design advice
> Date:          Sat, 27 Feb 1999 19:55:12 -0500

> i would seriously consider not using 432 as the if due to the hamonic
> relationships between the 2 bands...the tx mixer will mix 432+864=1296 but
> 432x3=1296, at 1296.1 the tripled signal is only 200khz away from the mixed
> one making filtering difficult
> 
> dave
> 
> ww2r


Dear Dave,

Your right.  I guess the question is "how good is the third harmonic suppression"
of the transmitter? So far I've been able to build filters with 60-70db of suppression
of the second harmonic on 222Mhz.  I should be able to obtain as much or better
of the third (unless something is going on that I don't understand, that's sure possible :-)).

My plan is to use a three or four pole helical resonator to clean up the 432 signal.
What do you think?

I don't want to use two meters as the I.F. since that's my receiving I.F. for the 2.4Ghz
converter.  So, I don't want to be transmitting in the same IF band that I'm receiving
in.  Any ideas?

--73-- David WA0AUQ

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