At 3/21/2005 05:50 PM, you wrote:
>Mike,
>
>Try placing a 3db attenuator in the receive line. If the result is
>the same or better, the duplexer needs tweaking.
Since the duplexer was already retuned with no change in performance, I'd
say it's not likely that it would need retuning if use of the pad yields
better sensitivity. More likely that the front-end doesn't like the highly
reactive load at the duplexer RX notch freq. & is breaking into oscillation.
> My guess is that
>the receiver is not presenting a 50 ohm load to the duplexer. This
>would make the factory tuning off, as they are tuned with perfect 50
>ohm loads. Not an uncommon problem.
Yes, but that's more of a problem with the notches than the passes, since
they're much narrower. Since the problem is being observed with the TX off
& no other signals present, notch accuracy isn't an issue here.
Bob NO6B
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