[Heathkit] Re: SB-620 Diodes

[Michael Tallent]

They are called Selenium cartridge rectifiers.  If you take off the end cap,
you will find a stack of selenium elements that are stacked to increase the
PIV voltage, they have a low current rating as they were used in high
voltage low current applications such as focus rectifiers in TV sets.  Some
had a PIV of 6000 v and they were 2-3 inches long.  The ones shown in your
picture would have a lower PIV rating due to their shorter length.

Mike Tallent W6MXV

----- Original Message ----- 
From: "Ken Kaplan" <krkaplan at cox.net>
To: "R. Blackman" <richard.blackman at sympatico.ca>; "HEATHKIT"
<Heathkit at mailman.qth.net>
Sent: Sunday, August 14, 2005 12:15 AM
Subject: [Heathkit] Re: SB-620 Diodes


> Richard,
>
> Good question as it got me curious enough to open up my SB-620. The parts
you refer
> to are diodes D3 & D4. I've never seen a part like that before. The only
seleniums I'm
> familiar with are the square plate type. I took a picture of mine. It can
be seen at:
>
> http://www.qsl.net/kb7rgg/heath/sb620pic1.jpg
>
> btw - the 3 big capacitors in my set are rather wet with some oily
substance. There is
> actually a wet "puddle" between C47 and C49. Does this mean its time to
replace these
> caps? Any good source for such high voltage types? C48 & C49 are .1uf at
1200vdc and
> C47 is .15uf at 1600vdc.
>
> I haven't had power on this scope for quite some time. I am in the
planning stage of
> setting up a complete station (SB100/SB600/SB610/SB620/SB630). I just need
to build
> a desk to hold everything. It's my motivation to upgrade my license.
>
> 73 Ken kb7rgg
>
> > Hello to group.
> > I am repairing an SB-620 and require the two selenium diodes   P/N 57-44
> > Does anyone  have suitable cross reference replacement ? /  specs?
> > My web search has come up zip.
> > Richard / VA3NDO
>
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