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Guenter Scholz
Guest
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 Posted:
Mon Nov 22, 2004 2:29 am Post subject:
Popping noises in a vintage tube radio |
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Please help with the above. the popping noises are on all bands, so I assume
it likely is dried out electrolytics in the power supply. When I have the
radio apart, anywhere else that I should be looking if that is not the case?
- thanks and cheers
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Sander deWaal
Guest
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| Posted:
Mon Nov 22, 2004 6:05 pm Post subject:
Re: Popping noises in a vintage tube radio |
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scholz@sciborg.uwaterloo.ca (Guenter Scholz) said:
| Quote: | Please help with the above. the popping noises are on all bands, so I assume
it likely is dried out electrolytics in the power supply. When I have the
radio apart, anywhere else that I should be looking if that is not the case?
|
Could be anything, from bad electrolytics via bad resistors to bad
tubes. Hard to tell.
--
Sander de Waal
" SOA of a KT88? Sufficient. " |
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Hot Glass Audio
Guest
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| Posted:
Mon Nov 22, 2004 10:05 pm Post subject:
Re: Popping noises in a vintage tube radio |
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scholz@sciborg.uwaterloo.ca (Guenter Scholz) wrote in message news:<cnriv0$8ig$1@rumours.uwaterloo.ca>...
| Quote: | Please help with the above. the popping noises are on all bands, so I assume
it likely is dried out electrolytics in the power supply. When I have the
radio apart, anywhere else that I should be looking if that is not the case?
- thanks and cheers
|
The electrolytics are likely faulty, but I wouldn't connect them with
the popping noises. I'd be checking the wax/paper coupling capacitors
and the resistors. If the 'lytics are shot, you'll have massive hum in
the audio output.
The wax/paper capacitors should all be replaced, as they absorb
moisture from age, non-use, and the moisture ruins the dielectric
properties and causes the caps to leak.
The resistors are most likely really cheap carbon composition types,
they drift severely with age, and can turn noisy. Playing the set for
a while could bring the drifted resistors back down to spec sometimes,
but it would be best to just replace them with carbon film 10%
tolerance types.
I had an RCA 66X3 that would work intermittently on shortwave, other
times the output would just be a series of pops and crackles. In my
case, the problem was a faulty plate resistors. I found that nearly
every resistor in the set had a tolerance of 50% or greater, they were
far out of spec. Replacing the caps and resistors cured the problem.
Best regards,
Ryan |
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Robert Casey
Guest
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| Posted:
Tue Nov 23, 2004 2:05 am Post subject:
Re: Popping noises in a vintage tube radio |
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Guenter Scholz wrote:
| Quote: | Please help with the above. the popping noises are on all bands,
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Possibly bad caps in the IF transformers. They often used
a mica wafer with silvering deposited to create a pair
of ~100pF caps. Problem is that there is often overspray
of the silvering, causing migration paths that build up
over the years. See my page
http://www.geocities.com/wa2ise/radios/repair.htm
about 1/3 to half way down. Also look at
http://oldradio.ca:83/Radio/IFxfrmr/ifcancaps.html |
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