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RE: preamps



Hi AMSATs,

One most important thing I still didn't see mentioned.
I have seen hams with having excellent pre-amps, but
still didn't got much better S/N ratios.
The reason is that they connect the ore-amp at the
tranceiver side, with a long cable to the antennas at
the input. 

Its easier to mount, no rain problems, no change in
the antenna situation... many reasons, but in
technical way it is not the way to do so :o)

What you need is a mast-pre-amplifier (with extra care
to the word "mast"). For satellite use you don't need
ultra low noise-fugures and very high gains. A good
antenna is even so important and do even better.

The low the NF the better, but also more expensive.
Because we do not receive signals from deep-space a
medium type would be okay. 
The gain of the pre-amp has to compensate the cable
losses. To much gain will feed the tranceiver with to
much input levels and might be overloaded.

I have the SP-2000 and SP-7000 of SSB electronics and
use them always. These pre-amps need to be mount in
the mast and are rain proof. They can be feed via coax
cable (most satellite tranceivers have 12V DC output
via the coax, like the FT847).

Ofcourse there are many other models available, I just
give my situation as an example.

73 PE1RAH
William
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