What I have observed is only a small reduction in sensitivity, but reduced dynamic range and AVC action. Strong stations are more likely to overload the receiver and cause audio distortion, and intermodulation can increase too. Audio output power will decrease, but is usually not a problem with headphones. I observed these when experimenting with 90 volts plate voltage on a BC-348. 20 volts into an unmodified BC-348 with the dynamotor power supply reduced sensitivity slightly but audio power dropped considerably for a speaker. Headphone audio was still pretty good. I also experimented with 80 volts instead of 130 in a Collins 75S-1 receiver, with comparable results. The audio power out for a speaker was noticeably reduced.

   B. Gentry, KA2IVY

Has anyone had experince with receiver HV lower than the nominal 235 VDC dynamotor output? I like to run everything at or slighly below ratings. Not interested in squeezing out every last watt from the transmitters, etc.

So except for the times I am using the dynamotors, I run the receivers in the test jig and out of the racks at about 175VDC, transmitters at about 540VDC. (By the way, even 175VDC is enough to blow the .05's, so I am on a long term quest to replace all, either with re-stuffed cans or just wiring them in. Otherwise, letting them fail is like playing condenser Whack-a-Mole)

My question is about the receivers... aside from maybe the 12A6, are there any downsides to lower overall plate voltage?

Thanks

Ken 

W2EWL

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