Hello, I have a Motorola 4 can duplexer out of a UHF MSR2000 series radio that is the pass/notch style. I am pretty sure Motorola also used this same duplexer on the MSF5000 series of radios. I can not find any info on this unit and I am having a problem with the notch on the low pass side. I can not seem to adjust the notch past 4.5 MHz spacing. It will adjust down to 3 MHz spacing just fine. The notch on the high pass side adjusts just fine and will actually go a little beyond the 5 MHz spacing.
The pass adjusts properly on both sections of the duplexer. It was originally on 464/469 and I retuned it to 440.8/445.8. The notch problem was there on the original frequency as well. I am using a IFR A-7550 analyzer/tracking generator for alignment. the duplexer has very good insertion loss and the notches are -100 db, so it is meeting specs very well, other than the one notch being off. Has anyone ran across this before or have any ideas. I though I would ask the group, before I started drilling out pop rivets to disassemble the cans from the mounting bracket. Thanks, Joe
