# Hypothetical question: Repeater with power amplifier

This is my first time ever asking a question on stack exchange or any stack site, so please be gentle if I missed something here.

I am currently working on building a UHF (GMRS) repeater, and while picking equipment and such, I got to thinking about whether a power amplifier is something that can be used with a repeater. I don't intend to run an amplifier, but was wondering if it is theoretically possible. I have done some web searching and haven't had a whole lot of luck finding the answer I am looking for. I was wondering if someone could confirm whether my theory is correct..

Consider the following, fairly basic, setup: Dual commercial radios connected to a properly tuned UHF cavity duplexer sharing a single antenna for both RX and TX. If I were to put an amplifier on this rig, I would need to place it on the transmit radio side of the duplexer, NOT on the antenna side, correct? I assume that, if placed on the antenna side, the moment the transmit radio keyed up, it would shut off any signals coming in to the receive radio effectively disabling the system to be used as a repeater at all.

In short, if you want to run a power amplifier with a repeater, you would potentially need two devices.. a pre-amp for the receive, and a power amp for the transmit, connected as follows:

RX <== Pre-Amp <===== |----------|
| Duplexer | <===> Antenna
TX ==> Power Amp ===> |----------|


(I hope the diagram makes sense lol)

Is my thinking on this correct?

73s, Steve

• Hello Steve, and welcome to ham.stackexchange.com! Oct 26 '20 at 18:04