01-14-2018, 01:56 PM
I am restoring an early 50s FADA AM/FM radio for a friend. There are a mix of paper and ceramic capacitors inside. (And a few electrolytics.)
One type that I think must be ceramic are hard, white cylinders, smaller than paper, labeled "Hi Q 1500 mmF 20%." There are similar caps with other values ranging from 2 pf to about 250 pf. None are marked with a voltage spec, nor does the parts list say anything about voltage.
My question is, are these high temperature stability caps? Most of them don't look like they are associated with the oscillators or anywhere else requiring high stability. The exceptions are some 2 mmf, 10 mmf and 30 mmf caps that the parts list call "FM Oscillator coupling," "osc. feedback," and "osc grid cap," so those could need to be stable with temperature.
Some are bad. My question is, do I need to look for temperature stable caps, or can I replace them with poly or mica caps 500 volts or higher to be safe? If I do need high stability caps what type should I use and where would I find them?
Thanks!
One type that I think must be ceramic are hard, white cylinders, smaller than paper, labeled "Hi Q 1500 mmF 20%." There are similar caps with other values ranging from 2 pf to about 250 pf. None are marked with a voltage spec, nor does the parts list say anything about voltage.
My question is, are these high temperature stability caps? Most of them don't look like they are associated with the oscillators or anywhere else requiring high stability. The exceptions are some 2 mmf, 10 mmf and 30 mmf caps that the parts list call "FM Oscillator coupling," "osc. feedback," and "osc grid cap," so those could need to be stable with temperature.
Some are bad. My question is, do I need to look for temperature stable caps, or can I replace them with poly or mica caps 500 volts or higher to be safe? If I do need high stability caps what type should I use and where would I find them?
Thanks!
John Honeycutt
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