[Boatanchors] solid state replacements for 5R4 rectifier tube

Sat, 9 Feb 2002 10:12:45 -0800

Nebraska Surplus Sales has these for sale.
----- Original Message ----- 
From: "Barry Hauser" <[email protected]>
To: <[email protected]>
Cc: <[email protected]>; <[email protected]>
Sent: Friday, February 08, 2002 10:18 PM
Subject: Re: [Boatanchors] solid state replacements for 5R4 rectifier tube


> Hi Bob:
> 
> I don't know of a source offhand.  I have an old 5U4 "Solidtube" which
> basically consists of a potted octal tube base with two rectifiers in it.
>  You really don't need the tube replacements, you can either harvest the
> base of a defunct tube or buy fresh bases from AES and others.  Then just
> solder in the appropriate rectfiers - allowing a healthy margin for PIV
> and wattage.  You can also solder the rectifers to the appropriate tube
> socket terminals.  I've seen some cases where the leads were thick enough
> that someone just bent and trimmed them and inserted them into the socket
> on top.
> 
> However, retrofitting solid state rectifiers usually results in higher B+
>  than specified, and in combination with higher line voltages -- 120 to
> as high as 126, which I have here, vs. the 110-117 of yesteryear -- you
> can be way over, and possibly enough to exceed the working voltage of
> some components.  You would have to check the B+ and add a dropping
> resistor to get it back down as needed.  Even that 5U4 replacement came
> with a little instruction sheet warning of exceeding B+ level and that a
> resistor might be needed.  (Imaging the TV set owner who thought -- "Oh
> goody, I can replace that 5U4 that's always burning out once and for
> all", then reads the caveat.  Didn't say anything about that on the
> outside of the package.
> 
> In addition to "too high" there's such a thing as "too quick".  With
> solid state rectifiers, the B+ turns on immediately -- ahead of the
> warmup delay of the filaments of the tubes in the set.  I'm not totally
> up on this aspect, but it's supposed to be a bad thing for tube
> longevity.  Might be theoretical, as many R-390A's are running with solid
> state rectifiers in place of their 26Z5W's and many report no problems.
> 
> Unless you absolutely must reduce heat, I'd stay with the tubes.  For the
> 5R4, you might want to go with the heavy duty replacement -- 5R4WGB or
> 5R4WGA/B/Y  -- usually made by Chatham but also others, like Raytheon,
> Cetron, etc..  These look like ice cream cones - the flat bottom kind --
> and have extra thick glass envelopes -- coincidently flat-topped.  They
> cost a bit more but still available at reasonable prices.  I don't know
> if they'll physically fit in the HT-32 -- nearly twice the diameter of a
> regular 5R4 w/o "shoulders" (ST type).  
> 
> Running out of B/W here.  If you want some sources for those, let me
> know.
> 
> Barry
> 
> 
> 
> 
> , On Fri, 8 Feb 2002 19:58:30 -0600 "Bob Raley" <[email protected]>
> writes:
> > Does anyone on the list know of a source for these?  I checked with 
> > AES and
> > they don't stock them.  If you know of a source please let me know.  
> > I'd
> > like to purchase a couple of these to replace the 5R4 and 5V4 in my 
> > HT-32.
> > 
> > Thanks..................................Bob kg5r
> > 
> > _______________________________________________
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> > http://mailman.qth.net/mailman/listinfo/boatanchors
> > 
> 
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