Topband: YCCC 9 Circle preamp failure
ve6wz at shaw.ca
Fri Sep 13 14:55:20 EDT 2019
After 2.5 years of flawless operation, earlier this summer my YCCC 9 circle rx array started to develop some strange inter-mod noise, and random junk showed up on 160m when using the array.
I isolated the problem to be the .1 uF coupling capacitors on the input of the amps. This happened on 4 of the 9 amplifiers.
The most likely cause is from TX overload because this array is only about 125’ from my parasitic TX array. (the TX antenna is detuned when on RX and presents no issue on receive).
At first I suspected a nearby lightning strike, but the 4 failed amps happen to be the closest to the TX array, nothing else in the amp was damaged, and there was no other evidence of a lightning event at the station.
Here is a link to a YouTube video I made showing how I isolated the problem. Using my scope I show how the output from the damaged amp has significant phase and amplitude distortion, and using the multimeter the failed caps are evaluated.
If you have one of these arrays, I show how it is very easy to test the pre-amps in the field using your multi-meter to confirm if a similar fate has occurred in your system.
73, de steve ve6w
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