What is a Duplexer? How it works and common failures

[@houseofstylz]

Thanks Dave, for video & recent technical assistance.

[@cjammer34]

Nice video. Couple things I would like an answer to: 1) does it matter which TX/RX is tuned to TX or RX? I see them marked as HIGH and LOW. 2) this may be part of question 1, but the internal coils are different. Why? if Question 1 Matters what happens if you tune them backwards? Which I can see being done easily because my radio TX Freq. and the repeater TX freq. are not the Same.

[@kg4lzc]

The Low side is designed to pass the low frequency and reject the High. The coupling is slightly different between the two sides of the duplexer. I have tried to tuned them opposite and didn't really have a lot of luck. The pass was really bad while the reject was ok.

[@SoCoguy]

Thank you Dave! Very good information, addressed my issue precisely. Jeff in Colorado

[@kg4lzc]

Thank you, and I'm glad your questions were answered!

[@brianjones3245]

Very similar to what the Marines call "Re-Trans" setup. But it used 2 separate antennas. One for transmit and the other for receive. Would that be possible for 2 KG-1000 radios in repeater mode? Use 2 antennas instead of a duplexer?

[@kg4lzc]

A duplexer allows the user to utilize one antenna. Without a duplexer, you would need two antennas. And, yes, we used 'Re-Trans' setups in the Marines. However, I didn't understand exactly how they worked back then.

[@daveengstrom9250]

Never use ten words when you can use ten thousand.

[@OnAirVoice]

Tuning those things is no fun, I did one 20 years or so ago. I would not even know where to start now. That one had WAY bigger cans. Had borrow.a spectrum analyzer.