I'm looking for a replacement, or a substitute, mains transformer for a
Hallicrafters SX-42 ... the existing one sizzled and died :-(

The specifications a 115V primary, 500V C.T. @ 142mA, 5V @ 3A and
6.3V @ 5.3A, and the mounting holes are 3.75"x3.00".

If anyone knows a likely source for a replacement, please let me know.

Thanks!
Julian

jjbunn wrote:

I'm looking for a replacement, or a substitute, mains transformer for a
Hallicrafters SX-42 ... the existing one sizzled and died :-(

The specifications a 115V primary, 500V C.T. @ 142mA, 5V @ 3A and
6.3V @ 5.3A, and the mounting holes are 3.75"x3.00".

If anyone knows a likely source for a replacement, please let me know.

Thanks!
Julian


Try http://www.oldradioparts.com

And there's always ebay. Unfortunately old large transformers and
audiophile prices tend to go hand-in-hand but you might get lucky. I
recently found one for an 18-tube set of mine for $19. I guess it was
"too big" for audio gear
The Vintage Electronics category is where to look.

GL, Bill

Julian,

Any chance the failure is visible, and fixable?

An option here is to get your tranny rewound. There are lots of folks
that offer this service, or you might take it on as a DIY project. If you go
this route, you could simplify the winding task by only making one winding
of 250 vac, and use a full wave bridge rectifier consisting of two silicon
diodes on the negative side (-) and the vacuum tube 5U4 rectifier on the
positive side (+). If you go this route, you can beef up the HV secondary
wire size since there will be room, and it may be easier to handle a larger
wire than what was originially there. You can also modify the turns ratio to
better match today's higher line voltage. I bet the SX-42 tranny was
designed for 110 vac AC mains whereas today we often have about 122 vac at
our outlets.

As a FYI for still working open frame boat anchor transformers, you can
preserve them by vacuum impregnating them with transformer varnish. This
will fill in the voids where a failure is imminent, but hasn't happened yet.
This can be a DIY project where you can use car manifold vacuum, some
tubing, fittings, and a suitable container. Take the end caps off first to
expose the windings. If the wires have bad insulation, you can cut them 1"
from leaving the core, and strip back. Add on new wires and heat shrink the
connection. As for doing the varnish bit, it's neat to watch the bubbles
exit the transformer as the air is pumped from the container, and then when
you let the air back in, that forces the varnish into all the cracks and
pores of the inner area of the transformer. Repeat two more times to get the
job done. Then hang until dripping is over, and bake to cure (temp and time
depends on varnish used). Instead of varnish I have also used electrical
rated RTV thinned out with chlorethane until it is a white milky soup.

Jim
WD5JKO

"jjbunn" wrote in message
oups.com...
I'm looking for a replacement, or a substitute, mains transformer for a
Hallicrafters SX-42 ... the existing one sizzled and died :-(

The specifications a 115V primary, 500V C.T. @ 142mA, 5V @ 3A and
6.3V @ 5.3A, and the mounting holes are 3.75"x3.00".

If anyone knows a likely source for a replacement, please let me know.

Thanks!
Julian

"jjbunn" wrote in message
oups.com...
I'm looking for a replacement, or a substitute, mains transformer for a
Hallicrafters SX-42 ... the existing one sizzled and died :-(

The specifications a 115V primary, 500V C.T. @ 142mA, 5V @ 3A and
6.3V @ 5.3A, and the mounting holes are 3.75"x3.00".

If anyone knows a likely source for a replacement, please let me know.

Thanks!
Julian

Julian -

An option is a transformer company. Heyboer Transformers
in Grand Rapids, Michigan does this work --
you may also have a suitable rebuilder one in California.
http://www.heyboertransformers.com/

You can provide them with specifications, an the old transformer for proper
sizing -
they matched the wire colors and used the old bells on the new transformer.
Professional job on a rebuild for me late last December.

BTW, you should specify that primary should be 120 VAC --
instead of 110 V of the original - due to higher line voltages -
this should operate cooler in the SX-42.

w9gb

g. beat @ wrote:


Julian -

An option is a transformer company. Heyboer Transformers
in Grand Rapids, Michigan does this work --
you may also have a suitable rebuilder one in California.
http://www.heyboertransformers.com/

You can provide them with specifications, an the old transformer for proper
sizing -
they matched the wire colors and used the old bells on the new transformer.
Professional job on a rebuild for me late last December.

BTW, you should specify that primary should be 120 VAC --
instead of 110 V of the original - due to higher line voltages -
this should operate cooler in the SX-42.

w9gb

Heyboer does nice work and I've used them but I would think they are
prohibitively expensive for this project. You'd looking at around $150
for one this size.

-Bill

"- exray -" wrote in message
...

Heyboer does nice work and I've used them but I would think they are
prohibitively expensive for this project. You'd looking at around $150
for one this size.

-Bill

It may be that expensive for the SX-42 model, but the transformer for my
specific project in
December was $100 with shipping - and they had it back to me in less than
one week!

Greg

Thanks Bill!

I looked the they have a great selection, but nothing that quite
fits the bill (!). I've sent them an email to double check anyway.

Julian

Hi Jim,

Thanks for the super advice. The transformer died after some "fizzing",
and now one half of the primary is O/C.

I have an old HP/Paeco transformer which has several 6.3V taps, and a
5V tap for a 5U4. However, the HV secondary is for a B+ of 440V ... too
high (the SX-42 needs 250VDC). So I don't think I can make that work
easily.

Julian

Thanks ... I think this would work out very expensive, but is a good
fall-back if all else fails.

Julian