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K0CQ > HELP 01.05.08 05:17l 32 Lines 1487 Bytes #-6647 (0) @ WW
BID : 45064_W0AK
Read: GUEST
Subj: Re: TS830S fault
Path: DB0FHN<DB0MRW<OK0PKL<OK0PCC<OM0PBC<OK0PPL<DB0RES<OE6XPE<IW2OHX<IQ0LT<
I0TVL<CX2SA<N6RME<KG6BAJ<WH6IO<N0KFQ<KB0OFD<KQ0I<W0AK
Sent: 080428/2029Z @:W0AK.#CIA.IA.USA.NOAM #:45064 [Des Moines] $:45064_W0AK
From: K0CQ@W0AK.#CIA.IA.USA.NOAM
To : HELP@WW
Carbon Composition resistors have never had great stability. They
drift (usually upwards) with heat, age, and humidity exposure.
After 20 years or more probably half the resistors in a radio
will have drifted out of tolerance. In some circuits that won't
matter much, but in others it will upset circuit function.
Resistors operated near their power rating get hotter and move
more rapidly.
Then the miniature aluminum electrolytic capacitors used in
vintage (and new) solid state radios were never great quality and
often plain junk (but cost only a few cents each neglecting the
cost of insertion and soldering) and have a history of aging
rapidly leading to poor performance. I you don't have a capacitor
checker with power checking capability, it may be cheapest to
simply replace all the accessible miniature aluminum
electrolytics. The best ones these days have a high operating
temperature rating and low ESR (Equivalent Series Resistance).
The least expensive ones often don't pass my power factor checks
when new.
I hadn't thought about rivets in rotary switches, but I'll add
them to my repertoire of things to check, perhaps with a solder
dot to make the fix permanent. I know that switch contacts often
conduct better after an application of a partial drop of DeoxIT
followed by abrasion of operation.
73, Jerry, K0CQ @ W0AK.#CIA.IA.USA
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