[Hallicrafters] Re: [Boatanchors] solid state replacements for 5R4 rectifier tube

[Radio Randy]

Hi Guys,

I'm not sure but, I seem to recall that those "solid state" tube
replacements also had resistors in series with the diodes. This was to
imitate the voltage drop experienced when using the actual tube itself. It
might also have kept the inrush current under control.

Someone correct this if it's wrong. Thanks.

Radio Randy

----- Original Message -----
From: "Barry Hauser" <barry_hauser at juno.com>
To: <raley at emptychair.net>
Cc: <hallicrafters at mailman.qth.net>; <boatanchors at mailman.qth.net>
Sent: Friday, February 08, 2002 10:18 PM
Subject: [Hallicrafters] 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" <raley at emptychair.net>
> 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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