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Re: Mode J Recieve Desense Problems



-> Forget the complex fixes; try the cheapest first: a stub.
->
-> This forms an electrical short-circuit at the frequency it is set for
-> so, on the 70cm rig antenna line, you tee off a 2m stub. You tune it
-> by starting with a length thats too long and snip bits off until you
-> hit the sweet spot.
-> Trouble is that I can't remember whether you want a quarter-wave or a
-> half- wave ... and whether its open-circuit or closed. But I'm sure
-> someone else on the -bb will know this and post.

Excellent suggestion, Richard! I have even used this fix on repeaters
before, and forgot about it. The way I implemented it previously was to
use a pass cavity tuned to the frequency I wanted to eliminate "teed"
into the antenna/preamp circuit, and then a 50 ohm load on the other
side of the pass filter. It works exactly like you describe, just no
tuned radiator. A simple mobile duplexer would do the job as the pass
band device.

Regards,
Steve Diggs, W4EPI
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