Batboard

Hi Guys,

Further to the last post, when I'm on site I'll also be having to check out an internal duplexer in a VHF GR1225 repeater. I have never done anything with ones of these duplexers. Can someone tell me how to tune one or verify? Also, anything I should look for?? What are the max and min separations?

i don't have the model number, I'm ASSUMING that it is a standard model that was ordered with the GR1225 from Motorola.

Tx - 162.xxx
Rx - 167.xxx

Thanks!!

Internal duplexers in the GR1225 VHF repeaters are a notch-notch type. They notch out the TX frequency on the receiver input side. They notch out or filter out the receiver frequency in the TX side.

An easy test... DISABLE the RPT function, reverse the duplexer TX and RX ports, feed a RX signal into the antenna port, and there should be at least a 50 Db LOSS thru the duplexer's TX side to the receiver.