At 7/26/2008 15:26, you wrote: > > wd8chl <[EMAIL PROTECTED]> wrote: > > If the duplexer was supplied from Telewave on 2M, then > > what you have is right. LEAVE THEM ALONE!!!!! > > They just aren't that critical people!!! > > > > Even if it was originally on 150-160, it would still be fine! > >I don't agree... nor do I care to argue with you about the >hard numbers. > >I have a number of TPRD-1454 and TPRD-1554 duplexers here and >the difference in specified cable lengths for each model and >it's default frequency does change the performance enough to >make me not want to use the wrong/other frequency range cables >in the adjacent band/range.
I believe the problem at the duplexer T is the mismatch created by the wrong cable lengths. The reject is supposed to "look" like an open at the T so that the pass freq. passes through the T without any added mismatch from the reject side. If the cable lengths are off a little, the open becomes a slight reactance that will show up as some reflected power at the TX & (if you were to TX into the RX port of the duplexer for tuning) RX ports. Try tuning each side of the duplexer separately without the T, then connect the T with a 50 ohm load on the antenna port. If the reflected power is unacceptable, the cable lengths are probably the problem. Bob NO6B
