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Microwave signal generator



Greetings, I am contemplating the path I will need to take to receive
S-band on AO-40, and on a hunch I picked up a surplus HP 8616B microwave
signal generator at a recent hamfest for $20. I figure if nothing else,
it might be useful for testing and alignment purposes of whatever
downconverter I end up getting to feed my FT-736.

I was discussing my plans for it with the guy I got it from, and he
suggested that the signal generator could prove useful as a local
oscillator for my S-band receiver by tuning it the appropriate frequency
needed to produce a mixing product in the 2 meter band.  I have only a
vague idea how to do this, I can probably map out a block diagram, but
am a bit intimidated about the practical aspects of making it work.

A couple of practical concerns about the generator are also on my mind
as well. First, any receiver would have to be at or near the antenna,
since line loss over a nominal 75 foot run of coax, or even 7/8 CATV
hardline would be enormous at 2.4 gig.  Since the generator is a large
rack mounted piece of 1960's high technology, it is not practical to
mount it near the feedpoint of the antenna.  I would have to run coax
from the generator out to the downconverter at the antenna, and expect
from 20 to 30 dB of loss, even with top quality feedline. The signal
source is probably strong enough to overcome this, but I really have no
idea how much signal I need.  The 145 Mhz downlink should be fine with
9913, LDF4-50 or whatever decide to use.  Another concern is the
stability of  the signal source, for even a 0.1 percent drift at those
frequencies is a couple of Mhz.

It is an intresting concept, but before I invest any serious amount of
time or cash into a project, I want to see if this proposal passes the
practicality test.

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