FCC Licensed Amateur Radio Operator, Extra Class

GMRS G.E. Mastr II Repeater Build and Alignment for K6JFS

It took me a while to gather the hardware and get everything ready to build this GMRS repeater for K6JFS, but I finally got around to getting it done this morning. It actually went very smoothly, expecially considering the fact I had to completely replace the original PLL type exciter with a non-PLL type and completely realign the repeater from its original commercial frequency tuning to GMRS range (roughly 11 MHz higher than it left the factory set up for.)

This set of photos gives a little rundown of the build, alignment, and final test results. I hope he gets many years of enjoyment and great use out of this machine.

This Mastr II had a PLL type exciter from the factory (lower left corner.) Due to the fact I had already recrystalled a non-PLL type transmit ICOM for this build, I replaced the PLL exciter subassembly with a non-PLL type.

Standard UHF exciter board installed in place of the factory PLL type exciter.

Transmit ICOM recrystalled for 462.700 MHz output frequency.

Receiver ICOM recrystalled for 467.700 MHz Rx frequency. The entire receiver system had to be realigned because of the +11 MHz shift in frequency.

Communications Specialists (ComSpec) TS-32 PL/CTCSS tone encoder/decoder board installed and wired for Rx and Tx tone operation.

Receive crystal “netted” for 465.500 MHz quite nicely, with only +1.0 Hz error. This build is utilizing “Low Side Injection” so the crystal has to be netted to 11.2 MHz below the actual receive frequency, using an 11.2 MHz IF offset.

Exciter and P.A./final output is nice and clean on the spectrum analyzer.

GMRS repeaters are not required to have automatic identification, so there was no need to remove and replace the factory installed Repeater Control and Audio modules and replace them with an aftermarket controller. I adjusted the repeat time-out timer to just over 3 minutes.

Built, realigned, tested, and ready to close up and give it a final “zipped up” test.

Closed and ready for one last round of testing before K6JFS takes delivery of his repeater (translation: “before he comes and loads up this heavy beast.”)

Final round of testing after closing everything up looked good. Showing only 9.0 Hz transmit frequency error, 4.41 KHz modulation (input/test signal was 1 KHz audible tone at 3.5 KHz deviation, and 123.0 Hz PL tone at 0.7 KHz deviation.) Output power can be adjusted to the required level with the simple adjustment of a potentiometer in the Power Amplifier assembly.



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