05-08-2020, 05:37 PM
I'm wrapping up repairs to a model 91 with a 225 chassis. There is a problem with plate voltages for the RF(44), detector oscillator(36) and the IF (44) tubes. The voltages are 265 to 272 volts, which exceeds the maximum plate voltage shown in the tube manuals. Measurements taken were at 115 volts on the line, plugged directly into a wall receptacle at 124 or 125 volts drives the plates up to 285 to 290 volts.Needless to say, the radio is very loud when the volume is turned up. Other than these voltages, the radio is working well.
Output of the power supply is 332 volts at the input to the filtering section and 286 at the output of the filter.
I have several solutions for lowering the voltage but I'd rather not put in parts that weren't in the original design if I can help it.
Any suggestions would be appreciated.
Thanks
Tom
Output of the power supply is 332 volts at the input to the filtering section and 286 at the output of the filter.
I have several solutions for lowering the voltage but I'd rather not put in parts that weren't in the original design if I can help it.
Any suggestions would be appreciated.
Thanks
Tom
Sometimes I wonder whether the world is being run by smart people who are putting us on or by imbeciles who really mean it.