None of the existing designs for transverters that are produced today with
work on 10GHz with a 28MHz IF. DEM, DB6NT even W1GHZ doesn't go there, just
not enough spacing between the LO and IF for proper filtering. 903 and 1296
are fine with new helical filters but above that, the performance is going
to be hurt. None of the pipe cap style filters have narrow enough bandwidth
and if you made a filter with narrow enough skirts, the insertion loss would
probably kill your signal. My suggestion is using your 28MHz rig to drive an
old Microwave modules 2m transverter or get a 2m IF strip from DEM which is
designed to do exactly this function. Yes, you have an extra LO to make sure
is on frequency but much easier to get on the band and make contacts that
way!
If you really want to continue down this path, I would suggest you contact
Paul Wade, W1GHZ and get his opinion. http://www.w1ghz.org/
73,
Terry - W8ZN
-----Original Message-----
From: vhfcontesting-bounces@contesting.com
[mailto:vhfcontesting-bounces@contesting.com] On Behalf Of Mike (KA5CVH)
Urich
Sent: Saturday, January 24, 2009 12:41 AM
To: Michael E Fox (N6MEF)
Cc: vhfcontesting@contesting.com
Subject: Re: [VHFcontesting] 28 MHz vs. 144 MHz IF
On Fri, Jan 23, 2009 at 20:06, Michael E Fox (N6MEF) <N6MEF@mefox.org>
wrote:
> I'm curious about whether to pick a transponder with 28 MHz or 144 MHz
> IF 1.25m and possibly for 33cm.
Mike wrote
The Radio Shack / Uniden 10 meter mono-band radios are somewhat popular for
IF radios.
--
Mike Urich, KA5CVH
http://ka5cvh.com
"The government cannot give to anyone anything that it does not first take
from someone else."
http://ka5cvh.com/political/democ.htm
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