Hi Everyone, I was helping a friend tune a Motorola T1502 duplexer yesterday, and got the following readings using a service monitor and GM300 receiver. I just want to confirm that what I did looks reasonable as I did tweak one of the band-reject loops since observing a low reading. The repeater is playing well with no desense detected. Readings below are just general noise levels keeping the squelch open.
RX Pair: High-side pass 457.000 = 0.4uV High-side reject 452.000 = 500uV TX Pair: Low-side pass 452.000 = 0.4uV Low-side reject 457.000 = 30uV The 30uV initially looked bad, so I played with the coupling loop on one can only (the 1502 is a four square can design) which raised the low-side reject 457.125 to around 300uV. This put the loop near the outermost position, but I was able to keep it fairly tight while making adjustments. I know that a tracking generator is the best way to tune duplexers, but having the service monitor/receiver should be acceptable. With 85 watts into the cans, we're getting around 55 out. The cans are spec'd at 1.5dB insertion loss which seems consistent with these readings. I might try and find another set of similiar cans or Wacom 678's for this site, if nothing to have a spare set. Thanks in advance for the feedback. Tony
