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Re: COMSAT PORTABLE SATELLITE UPLINK SYSTEM



>From: "David Lennig" <lennigde@muohio.edu>
>Yes, by "interesting" I meant adaptable for Ham usage.
>
>1.6Ghz, eh... could the transmitter be tweaked for L-band?
>>From the heat sinks visible in the picture, it must be "high" power.
>
>Anyone know what modulation scheme it uses? Probably FM?

David,

To summarize, I don't think that moving this equipment up 800 MHz higher is
trivial or even possible using the usual microstrip flaking, etc.  Often
you hear of hams modifying microwave gear, but that quite often involves
going to a lower frequency.  This is a bit easier in that the active
devices usually will work at lower frequencies.  So going down to 1.2G
might be done; not going up to 2.4G.  I would say the transmitter is in the
5w range.  The heat sink is needed because of the multiple stages needed to
get sufficient gain from the typical -6 dBm drive levels.

A person with good test equipment and design skills could remove components
and construct new stripline pcbs.  Basically all you would be getting is a
cheap source of  microwave transistors...after that you build it from the
ground up!  Its out of my league at present.  So I defer to others who have
experience in doing this.

As far as mode, FM?  I'm not sure; it may be some kind of digital voice
modulation [BPSK, CDMA,...?].  Anyone else out there know?

This would be a much more intensive project than modifying the Drakes or
other convertors that has been discussed recently.  David, I don't presume
to know what your technical skills are...but by the questions asked, I
would guess that this is not for you...yet.  But please keep positive
toward trying a microwave project.  Now maybe I'm way out of line and
someone else can lead you through a project like this.  It may cost you
$500 to start.  Take that same $500 to DEM or SSB or Kuhne and you can have
a 20w upconvertor for mode-L [ready to go].

Ed


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