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Old February 18th 09, 07:59 PM posted to rec.radio.amateur.homebrew
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Default AC/DC radio filter cap source?

What's a good place to get some good ones, reasonable? I've got
several AA5 radios with hum and need to fix them. All my new old stock
capacitors are dry.
thanks
Hank wd5jfr

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Old February 18th 09, 08:39 PM posted to rec.radio.amateur.homebrew
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Default AC/DC radio filter cap source?

On Feb 18, 1:59*pm, "Henry Kolesnik"
wrote:
What's a good place to get some good ones, *reasonable? *I've got
several AA5 radios with hum and need to fix them. *All my new old stock
capacitors are dry.
thanks
Hank wd5jfr


Finding the multi- section caps may be impossible. A local parts
dealer had some long skinny caps I bundled 3 of them together with
heat shrink for a replacement.
They were at Slayton's in Charlotte NC. Parts like that come and go
there and they often dont know what they have unless its regular
stock. Its a great place to browse on Saturday mornings.

Jimmie
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Old February 18th 09, 08:50 PM posted to rec.radio.amateur.homebrew
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Default AC/DC radio filter cap source?


"Henry Kolesnik" wrote in message
...
What's a good place to get some good ones, reasonable? I've got
several AA5 radios with hum and need to fix them. All my new old stock
capacitors are dry.
thanks
Hank wd5jfr


Buy new ones. Small, fresh axial and pc mount 160 to 450v. I was surprised
how much smaller than the originals.

http://www.nteinc.com/



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Old February 18th 09, 09:17 PM posted to rec.radio.amateur.homebrew
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Default AC/DC radio filter cap source?


"Henry Kolesnik" wrote in message
...
What's a good place to get some good ones, reasonable? I've got
several AA5 radios with hum and need to fix them. All my new old stock
capacitors are dry.
thanks
Hank wd5jfr


Hank

Check www.dialcover.com. Bill Turner makes look-alike
replacements in several values. They are good if you want
to keep the underchassis appearances. Otherwise, use
discrete axials.

Pete


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Old February 18th 09, 09:18 PM posted to rec.radio.amateur.homebrew
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Default AC/DC radio filter cap source?

http://www.dialcover.com/capacitors2.html

more to the point....




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Old February 19th 09, 01:39 AM posted to rec.radio.amateur.homebrew
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Default AC/DC radio filter cap source?

Henry Kolesnik wrote:
What's a good place to get some good ones, reasonable? I've got
several AA5 radios with hum and need to fix them. All my new old stock
capacitors are dry.
thanks
Hank wd5jfr

===================================
Suggest you look for good electrolytic caps in scrap (not too old) PC
SMPS units . I have removed quite a few of adequate capacitance and
working voltage to be used in valve (tube) type radio ,assuming AA5
radios are of the tube variety.
When removed from scrap equipment , it is best to slowly cycle them
(charge/discharge) a few times up to the stated working voltage .
If necessary test them in a real equivalent circuit and check ripple
with a scope . A bit of work ,but imho a rewarding activity.

Frank GM0CSZ / KN6WH
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Old February 20th 09, 03:54 AM posted to rec.radio.amateur.homebrew
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Default AC/DC radio filter cap source?

Henry Kolesnik wrote:
What's a good place to get some good ones, reasonable? I've got
several AA5 radios with hum and need to fix them. All my new old stock
capacitors are dry.
thanks
Hank wd5jfr



There's places like
www.triodeelectronics.com
www.tubesandmore.com
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Old February 20th 09, 03:30 PM posted to rec.radio.amateur.homebrew
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Default AC/DC radio filter cap source?

On Feb 18, 1:59*pm, "Henry Kolesnik"
wrote:
What's a good place to get some good ones, *reasonable? *I've got
several AA5 radios with hum and need to fix them. *All my new old stock
capacitors are dry.
thanks
Hank wd5jfr


Hey OM.
I used to make a living selling Mallory capacitors. Mallory came out
with a book called the Bird's and Bee's of electrolytic capacitors.
Well the electrolyte in these capacitors does dry out, but not from
sitting around in room temps. The electrolyte dries up from discharge
and charge, each time of a charge or discharge cycle the electrolyte
breaks down, into gas, that's why they have to be vented, or they
would explode. The electrolyte also dries up if you heat them up. In
the old days they used a lot of electrolyte.

So why don't they have capacity? The electrolyte in old style
capacitors has lots of room in between the plates and seperators, and
with time the electrolyte settles via gravity, At this point the
plates are no longer fully covered with electrolyte so the capacity
goes down the crapper.

When removed from scrap equipment , it is best to slowly cycle them
(charge/discharge) a few times up to the stated working voltage .
If necessary test them in a real equivalent circuit and check ripple
with a scope . A bit of work ,but imho a rewarding activity.


Frank GM0CSZ / KN6WH


^Is right for the most part, the key really is to ramp the voltage.
from 0 to full rated WVDC, up slowly, real real real slow, like days
to a week, this will wick the electrolyte back up on the plates and
once again the capacitor will be usable. So a NOS capacitor off the
self at room temp can be brought back from the grave

73 OM
de n8zu
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