SX-28 Power Transformer

WA8RVD · **Joined:** Apr Wed 04, 2012 3:54 pm **Posts:** 5

Hello All,
I have a bad power transformer in my SX-28. The manual says it should have a 580 volt center tapped @ 185 ma secondary. I have found Hammond transformers - one with a 550 v @ 230 ma secondary and one with a 600 v @ 230 ma secondary. Which would be the better choice?

Mike
WA8RVD

Ancient_Hacker · **Joined:** May Sat 22, 2010 4:42 pm **Posts:** 2331

You can always drop the voltage a bit with a resistor, but you can't easily raise it, so maybe go with the higher voltage one.

Then again, there's no need to push the voltage limits, the radio has plenty of gain and audio output power, so going a few volts low isn't going to hurt things significantly.

hbr nut · **Joined:** Jan Sat 12, 2008 12:25 am **Posts:** 52

Either one should work okay. Personally, I'd go with the 550VCT since the transformer will not be fully loaded and the measured voltage will likely be a bit higher than stated.

Darrell

K7MCG · **Posted:** Apr Wed 04, 2012 6:43 pm

Check the line voltage for which the Hammond transformer is specified - and your local line voltage. If Hammond specs at 117v and your line voltage is 125 volts (for example) you may want the lower of the two transformer output voltages.

--Chuck

WA8RVD · **Joined:** Apr Wed 04, 2012 3:54 pm **Posts:** 5

Thanks all for your advice -
I ordered one - I'll let the list know if it works. Be nice to know a replacement xfmr for an SX-28.
It's a Hammond 270HX

WA8RVD · **Joined:** Apr Wed 04, 2012 3:54 pm **Posts:** 5

UPDATE:
The transformer fit well and functions well. Hammond now has a tap on the primary so that it can be set up for 115 volts or 125 volts. This SX-28 lives again!

Johnnysan · **Posted:** Apr Wed 18, 2012 10:49 pm

How about some pictures.

WA8RVD · **Joined:** Apr Wed 04, 2012 3:54 pm **Posts:** 5

Sorry - no photos - it's back in its place on the shelf under everything else! The transformer went in with no new holes (of course) - there is a rectangular hole in the chassis for the old transformer and the mounting bolts for the new one captured the edge of this hole. Looks nice but not original! It does work fine. I removed a S.S. bridge rectifier that was soldered into the tube socket and it has a tube again! Paper caps and electrolytics replaced. I need to repaint the cabinet later this summer along with several others. Lots of fun.

Dougj · **Joined:** Oct Thu 13, 2011 11:47 am **Posts:** 3

where did you order the transformer from,

who has the best deal on transformers? , that 270hx looks like a good choice for my dead HQ-145A

my receiver isnt worh throwing a 100 dollar transformer in, maybe Ill find a good deal in Dayton...

Doug

WA8RVD · **Joined:** Apr Wed 04, 2012 3:54 pm **Posts:** 5

Hello, Doug
I got mine from Radio Daze but AES and Fair Radio among others carry them.

SX-28 Power Transformer

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