Mike,
Try placing a 3db attenuator in the receive line. If the result is the same or better, the duplexer needs tweaking. 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. Dick---N7ZH --- In [email protected], "Michael Singewald N1PLH" <[EMAIL PROTECTED]> wrote: > > OK, this is making me nuts. I have changed jumpers about 3 times > thinking I have a cable problem but I am convinced it is not the > cable. Here are the symptoms: > > 220 Hamtronics receiver (very old, no labeling on the board). Tunes > great on the bench (.15uv 12db sinad). Installed into rack still > tests great. Hookup to the duplexer and sensitivity goes to crap > (1.5uv). > However, if I back the PL connector (I know, not my repeater, just > helping) on the cable to the rx out of the T connector on the > duplexer, the sensitivity improves dramatically. As soon as the > ground on the connecter touches the duplexer the signal dies. > > I have done this without the tx transmitting but connected and > disconnected with no difference. My service monitor is hooked up to > the t connector on the antenna port of the duplexer. > > I could see if this happened with the antenna connected to the > duplexer. I would guess it is overload from other rf desensing the > receiver. But this is happening with the service monitor hooked to > the duplexer. > > BTW, this is a 4 can tx/rx duplexer that was sent to tx/rx to be tuned > and it came back doing the same as when it left so I don't think it is > the duplexer. > > I don't know enough about this but, could this be a problem with the > receiver and how it couples with the duplexer? I hate to order a new > receiver without being relatively sure that it is the problem. > > Thanks for any guidance! Yahoo! Groups Links <*> To visit your group on the web, go to: http://groups.yahoo.com/group/Repeater-Builder/ <*> To unsubscribe from this group, send an email to: [EMAIL PROTECTED] <*> Your use of Yahoo! Groups is subject to: http://docs.yahoo.com/info/terms/
