> Walter, this is a 577 rectifier tube replacement, manufactured in the 24th
> week of 1976, or now 25+ years old.
>
> Semtech hasn't made such items since the early 1980's. They are a local
> company, here in Newbury Park, CA and I know their products well. Problem
> with a lot of the old potted HV rectifier tube replacements is that they
> are potted with Emerson-Cuming Stycast epoxy which, unless potted under a
> vacuum, traps air bubbles that can invite corona.
>
> WB2WIK/6
>
> "Each success only buys an admission ticket to a more difficult problem."
> -- Henry Kissinger
>
> -----Original Message-----
> From: Walter Dail [SMTP:kt4ja@cfl.rr.com]
> Sent: Saturday, September 29, 2001 11:05 AM
> To: amps@contesting.com
> Subject: Re: [AMPS] 866A replacement .... SEMTECH STR4B32 ... any
> data please
>
>
> OK, while on the Semtech subject, I've got two Semtech STR 577,
> with "7624" underneath that number(probably a lot number??) They are about
> the same height as a 572B (maybe a little taller) with the four pins and
> anode cap.
> Does anyone have any data on these rectifier replacements? Ratings? I've
> searched
> the Semtech website with no luck.
>
> 73,
> Walter - KT4JA
>
> ----- Original Message -----
> From: "skipp isaham" <nospam4me@juno.com>
> To: <amps@contesting.com>
> Sent: Saturday, September 29, 2001 12:54 PM
> Subject: [AMPS] 866A replacement .... SEMTECH STR4B32 ... any data please
>
>
> >
> > -
> > : From: "Wynand van Wyk" <zs6arf@telkomsa.net>
> > : Hi all,
> > : I was today given two items at a flea market ... "you
> > : are the only one I know that will appreciate and use
> > : this in you amp projects" I was told.
> > -
> > At a flea market, it's most often the first indication that
> > one should look for the attached anchor chain...
> > -
> > : It turns out to be two items with a 4 pin base (fits into
> > : the 866A & 811A sockets) have hefty heat sinks and
> > : anode cap on top.
> > : About as tall as a 811A tube.
> > : Markings ..SEMTECH STR4B32
> > : My guess it is a replacement solid state rectifier for
> > : the 866A mercury valve rectifiers.
> > -
> > Not limited to the 866a replacement. There is a non
> > mercury similar tube to the 866a which from memory
> > is the 3B28 or 3B29.... one of those two numbers I
> > believe.
> > -
> > Solid state replacements are/were very popular as a
> > viable retrofit in tube power supplies. One must
> > consider the original 866a has quite a bit of voltage
> > drop while in operation. Same with the non merc
> > tube (and most tube rectifiers).
> > -
> > It is interesting to know that some mfgrs often relied
> > on the voltage drop as part of the circuit parameters.
> > Replacement of the tube rectified raises the supply
> > voltage, sometimes too high in certain circuits. There
> > have been failures from the elevated supply voltages.
> > -
> > For a block of time, equipment owners were replacing
> > vintage vacuum rectifiers with the ssr replacements.
> > Most "get away" with the higher output supply voltage.
> > They are made in all sizes and types, you happen to
> > have a common HV SSR 4 pin unit. They are also
> > manufactured for smaller supplies and popular in
> > some Collins Amateur Equipment.
> > -
> > Some of us pull them back out of our amplifiers to
> > restore vintage operation. In the tube guitar amplifier
> > groups I frequent, we consider the "sag" (operating
> > voltage drop) a feature. :-) They do offer a measure
> > of ruggedness and reliability vs glass packages. I've
> > never had one fail. There is a very slight increase in
> > amplifier power. Extreme or marginal circuits might
> > require adjustment of the zsac value.
> > -
> > I now run the non merc version in my 30-S1, the SSR
> > units work and work in lower profile power supplies
> > (which are viewed less often). Original 866a's
> > still glow in circuits that allow their operational view
> > from a safe position. The Viking Valiant is such an
> > example.
> > -
> > I'll look to see if I have a data sheet for your particular
> > ssr replacement.
> > -
> > : Any info and how I can utilize this in my High Voltage
> > : supplies appreciated.
> > : Wynand
> > : ZS6ARF
> >
> > Most of the installation instructions are basic plug &
> > play, but some are smart enough to advise caution
> > related to the resultant elevated supply potential(s).
> > -
> > cheers
> > skipp
> > -
> >
> > ________________________________________________________________
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> >
> >
>
>
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