02-13-2009, 10:03 AM
I measured the AC outputs of the power transformer with 110.8 volts input:
Input 110.8 AC (spec is 119)
B+ is 325 VDC (spec is 275)
High voltage 370 AC (spec is 440 each plate of 80)
Filament 5.85 AC (spec is 6.1)
Rectifier Filament 4.71 AC (spec is 5)
And the filters are 10mfd (spec is 8mfd)
So what is left? THE SPEAKER FIELD!!!! It measures 908 ohms (spec is 1600). So apparently it has some shorted turns - although the radio works fine (the part number on the speaker is correct, so it has not been changed). So I will do as suggested and add a series resistor chosen to produce 275 volts of B+ with 119 volts in.
Of course, that does NOT explain the problems with the Zenith 216-2. I guess I'll have to write that one off as a side effect of operating a 25-30hz radio on 60hz and using 10mfd filters instead of 6mfd. By the way, the draw is only 60 watts - spec is 85 watts (at 25 hz) - all tubes are good - output tube is NOS.
Input 110.8 AC (spec is 119)
B+ is 325 VDC (spec is 275)
High voltage 370 AC (spec is 440 each plate of 80)
Filament 5.85 AC (spec is 6.1)
Rectifier Filament 4.71 AC (spec is 5)
And the filters are 10mfd (spec is 8mfd)
So what is left? THE SPEAKER FIELD!!!! It measures 908 ohms (spec is 1600). So apparently it has some shorted turns - although the radio works fine (the part number on the speaker is correct, so it has not been changed). So I will do as suggested and add a series resistor chosen to produce 275 volts of B+ with 119 volts in.
Of course, that does NOT explain the problems with the Zenith 216-2. I guess I'll have to write that one off as a side effect of operating a 25-30hz radio on 60hz and using 10mfd filters instead of 6mfd. By the way, the draw is only 60 watts - spec is 85 watts (at 25 hz) - all tubes are good - output tube is NOS.
