[amsat-bb] Re: SSB SP-7000 rejection
k9qho6762 at sbcglobal.net
Sun Oct 5 15:03:37 PDT 2008
I have a SP-7000 and get some desense, but I think this is the reason. As I key on CW, the noise floor increases depending on the position of the antennas.
My antennas are only eight feet above ground. I notice the desense level changes as I rotate. If the antennas are a zero elevation, I get reflections back into the 435 MHz helix antenna from nearby objects. If I point the antennas above the ground clutter, I have no desensing.
This is a great preamp. I would try it without the duplexer first. By boom is about 6 ft.
I hope this helped.
Mike (K9QHO) AMSAT 33589
At 05:37 AM 10/4/2008, Tim Tapio wrote:
>I'm planning a new antenna system and planning on using an SSB preamp on the
>430 downlink side. The 7000 uses helical bandfiltering.
>My antenna separation will be on an 8' fiberglas boom. Will desense be an
>issues? Should I plan on using a bandpass filter such as a duplexer?
>Thanks and 73 de Tim, K4SHF
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