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Author Topic: Hammarlund Power transformer  (Read 5402 times)

Posts: 93

« on: April 29, 2011, 05:04:31 PM »

I am rebuilding some Hammarlund HQ 120 and 129 X's In one each , I have no power output and # 1 don't know what the output for the 120 should be and am fairly sure I will have trouble finding replacements for eather of them.
Any information would be great. Thanks in advance.


Posts: 4450

« Reply #1 on: April 29, 2011, 05:49:19 PM »

Schematics and service info here:

...says a lot about our society that Martin Shkreli went to prison for defrauding investors but not for price gouging lifesaving medication   -   Ken Klippenstein

Posts: 3161

« Reply #2 on: April 29, 2011, 08:25:55 PM »

Michael -

I am a bit confused by this statement in your question
I am fairly sure that I will have trouble finding replacements for either of them (transformers).
Any information would be great.

A number of Hallicrafters receivers were built in Chicago, largely using Chicago or Midwest component manufacturers.
Many of these companies still exist or have been acquired / merged over the past 60 years.

There are also a number of Antique Radio Receiver (1920s - 1950s) Restorers across the United States ...
this is actually a separate hobby and interest area.  500 members in the Chicago area club.

HERE is a very good web site for restorers to post Wanted items !

You have a group for Iowa, Minnesota, Nebraska and Dakotas

They will have a Radio Auction in Cedar Rapids, IA on May 7th !

Tom, W8JI has a nice photo of his Hammerlund HQ-120-X


There are still a large number of transformer manufacturers in this Great Lakes region.
The specificaitons for the transformers can be found in the manuals and
by reading the electrical schematics (both readily available).

IF you have the original transformers (failed or bad)
you can ship these transformers with the specifications to:

Heyboer Transformers Inc
17382 Hayes St.
Grand Haven, Michigan 49417
Phone: (616) 842-5830
Fax: (616) 842-3731

Heyboer normally charges $75 to $125 for winding a new transformer
to your form factor / size.  
While this may seem like a sizable $$ investment -- restorers appreciate the service --
and the USA is not building new thermionic receivers like this anymore  :-)

The guitar amplifier / musician industry regularly uses these services from Heyboer and other
firms - such as Sun Transformers in southern IL.

« Last Edit: April 29, 2011, 08:49:23 PM by W9GB » Logged

Posts: 93

« Reply #3 on: April 30, 2011, 07:32:05 PM »

Again, my assumptions need to be corrected.
When I started this project, I had no knowledge of what I was doing and didn't have Elmer to help. The information recieved, is some of the best I have incountered so far.
How I Aappricate all the information and tnx so much.

Posts: 68

« Reply #4 on: May 01, 2011, 07:48:56 AM »


I can make no claim to be an expert, but I also have an HQ-129x and an HQ-120x receiver. I was able to successfully rework the 129x, learning as I went along.

It sounds like you are having trouble with the power transformers? If the transformer is still in the circuit, I have two suggestions to make. First, look for the two .05 mfd AC bypass caps connected to the transformer primary. If they are shorted, then the fuse is likely to blow. If these caps are original, I would replace them with new AC rated bypass caps asap.

If you have 120 volts on the primary, pull the rectifier tube and check for high voltage AC at the tube socket plate pins.  This is the HV Secondary, Be Carefull!!   Pulling the 5U4G tube will isolate the high voltage windings from the rest of the power supply filter circuit; if these windings are good, there should be several hundred volts (500+ ?) across the rectifier plate pins.

A common problem with the HQ's, and most boat anchors, after many years, was leaky electrolytic filter caps. When the filters finally got leaky enough, the excess current tended to burn out one of the filter chokes. If your original chokes are still there, check them over. If the original filter caps are still there, replace "em. On my HQ-129, the first choke was gone, replaced with a high-wattage ceramic resistor. It seems to work fine, all my HV values are in line with the table in the manual.

If your transformer secondary is burnt out, a similar sized unit from an old 50's or 60's TV or tube radio would probably work, but they are getting hard to find. I would try to find a used junk TV or old radio to serve as a parts donor. Junk shops, surplus stores, garage sales? Craigslist or Ebay? E-ham classifieds? The old sets are harder to find now, especially ones with tubes and plate transformers.

73, Al

Posts: 4450

« Reply #5 on: May 01, 2011, 09:29:53 AM »

Someone should mention that Hammond Mfg. in Canuckistan might have a new transformer so close to the original that only Mrs. Hammarlund would notice.

And, if you're ever in Guelph, this looks like a cool place to visit:

...says a lot about our society that Martin Shkreli went to prison for defrauding investors but not for price gouging lifesaving medication   -   Ken Klippenstein

Posts: 5183

« Reply #6 on: May 02, 2011, 06:23:25 AM »

The transformer could be the problem (especially "primary open") but there are several other points in the AC winding circuit: Power cord, fuse, some bypass caps, power switch, etc that seem far more likely.

Transformers can and do go bad in a variety of ways (some spectacular and some quiet) but IME this is not endemic among Hammarlund's.

I would not believe the transformer had failed until you had ohmed out the windings and checked everything else in the primary circuit.

Posts: 93

« Reply #7 on: May 02, 2011, 06:14:15 PM »

Testing today I found the wire from the electrolytic cap going to the 5u4 was not connected which give me no power to anything. Went looking after your suggestions and am very grateful I have you "all" in my court. Now the old girl is defffff. and am tracking the reason Why.
Tnx Mike
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