I have a Wards Airline model 62-103 and after an hour the power transformer get quite hot. Runs cool for the first 20 minutes and the current drain on the primary stays the same at .66 A AC. I have recapped the set and the set runs good all the time. Seems to me that the transformer is going bad.

.66 amp means this set is consuming about 80 watts of power. That seems a little high, but may be normal for this set.

If you pull all the tubes and turn the set on for a half hour or so, does the power transformer still get very hot? If so, you probably have a shorted primary (i.e., bad transformer). If it runs cool, you might reinstall the tubes and take current readings on the B+ and filament circuits to see if one or the other is higher than expected.

Some sets were designed with marginally-rated power transformers to minimize recurring cost, so they tended to run very warm from the get-go. 1930's Zeniths were notorious for this. A hot transformer in itself isn't an indicator of a bad transformer; however, if it "smells hot" (not necessarily smoking) or drips wax or tar, it is probably overloaded. But that's no substitute for current measurements. If it's pulling and sourcing the right currents it's probably OK.

CV, you give good advice.

-Bill Grimm

John

Some power transformers saturate when operated at today's higher line voltage (125). This is an early AC radio from 1930's when line voltage would have been lower. (110-115)

Try dropping line voltage by 10 or 12 volts. This can be done with a wire wound resistor or bucking transformer.

http://www.nostalgiaair.org/Resources/250/M0011250.htm

Norm

:I have a Wards Airline model 62-103 and after an hour the power transformer get quite hot. Runs cool for the first 20 minutes and the current drain on the primary stays the same at .66 A AC. I have recapped the set and the set runs good all the time. Seems to me that the transformer is going bad.
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