Repeater maintenance update 8/8/2023

A work party consisting of members Garth KA7BVS, David KB7GFL, John AC7LC, Fred KE7HOD, and Erik K7QOG met with guest Karl N7TBN at the repeater site to determine the problem with the 2m link, and to test the radios. K7QOG brought a very fancy RigExpert antenna analyzer, and N7TBN brought a hefty oscilloscope to measure the power output of the radios.

The problem with the 2m link was quickly determined to be a lack of 12v power to the radio from the power supply. Turning the power supply on resolved this problem. The 2m link was tested and determined to be functioning.

Here are the power results measured by N7TBN and the SWR results measured by K7QOG, as recorded by KB7GFL:

The Direct value is straight from the isolated radio’s output.

The In-circuit value is measured with all the other system components (i.e. duplexer/splitter) in place to the coax that feeds the antenna.

444.125 mHz direct output: 35.5 watts
444.125 mHz in-circuit output: 17.3 watts
Antenna for 444.125 mHz has a 1.3 SWR

145.650 mHz direct output: 23 watts
145.650 mHz in-circuit output: 18 watts
Antenna for 145.650 mHz has a 1.2 SWR

The estimated power output of the main repeater system at the antenna is around 8 watts based on losses in the entire system (i.e. duplexer, splitter, connectors, and coax loss etc.) as well as the gain of the antenna.

224.180 mHz direct output: 28.8 watts
224.180 mHz in-circuit output: 9 watts — which is low (it is suspected the 220 duplexer needs tuning)
Antenna for 224.180 mHz has a 1.2 SWR

All radios have been tested and determined to be fully functional for the first time in a long time. Yay!



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