GM300 RF Stage - Tapping Driver Outputs

[Lewcifer]

I'm building a ham radio repeater and remote base using a pair of GM300 radios (1-10W version, UHF), a CAT-700b and Wacom BpBr duplexers. I also have a TPL UHF 100W rack-mount RF amplifier, which requires 8-15W in. To drive the TPL, I have a Mitsubishi brick UHF RF amp, which takes 50 mW in (yes... milliwatts) and produces 13W out. I'd like to tap one of the pre-driver stages of the GM300 transmitter directly, and bypass the 1-10W output stage. I need to do this so that I don't have to run an attenuator to the Mitsubishi UHF RF amp.

Does someone know enough about the GM300 to tell me what the RF output level is at the various RF driver stages in the radio?

Any suggestions or alternate suggestions on how to best accomplish this?

The two radios are:
M04GMC29C3AA
M04GMC09C3AA

Regards,
Lew Payne

[jackhackett]

According to the manual the level from the RF board should be around 25mW, the first PA stage brings that up to around 200mW, the second stage 2W, and the third stage as much as 15W.

[xmo]

Download the GM300 service manual at repeater-builder dot com

[Lewcifer]

According to the manual the level from the RF board should be around 25mW, the first PA stage brings that up to around 200mW, the second stage 2W, and the third stage as much as 15W.

Thank you, Jack... that's exactly what I needed to know. Very kind of you to share your knowledge with me.

Download the GM300 service manual at repeater-builder dot com

Been there, done that... even when looking at the schematics, it wasn't obvious to me.

Regards,
Lew Payne