Hammarlund IF transformers

[k1pjs]

Looking for Hammarlund HQ-145 IF transformers. In particular T5, T6 and T8. Is there a source available?

Thanks

K1PJS

[w3jn]

What happened - did the slugs freeze (and break) or are the fixed caps in the transformers bad?  Both very common in Hammarlund IF xformers.

Either one can be repaired.  No source for these except a junker (and chances are a junker's trannys would have the same problems), I'd advise fixing the ones you have.

[k1pjs]

Hello W3jn,

Yes, a couple of the transformers do have slugs that are frozen...the other 2 seem to have an open winding. I have not disassembled the transformers yet. Do you have experience with these?

K1PJS

[w3jn]

Yes indeedy, that's one thing I hate about Hammarlund receivers.

If you have open windings, chances are someone reefed on the slug and the form twisted and broke, pulling the wires from their terminals.  Just get in there with a tweezers and re-slobber the wires to their terminals.  You may need to use a short wire (IE a clipped resistor lead) to extend the terminal up a bit becasue the wire might be too short.  Wrap the IF wire around said short piece of wire several times, solder, check continuity, then solder that wire to the terminal.

If the coil is bruned out in the middle somewhere (apparent with a visual inspection) you're screwed, you need to replace the transformer.

As far as the slugs go, you need some  donor IF transformers with the same style of slug.  This is a painful and time consuming process, and you need to be very careful not to wreck the coil form.  Get in there with a small screwdriver and crumble it gradually, use a small drill bit works too (DO NOT try drilling it out with a power drill!).  Eventually it'll all come out.  Then just replace the slug with one from a donor xformer - one out of a cheapo tube broadcast radio, etc.

[WQ9E]

If the slugs are frozen, but not yet broken, you may be able to carefully get them loose.  Choose a metal allen wrench of the correct size to fit firmly in the core and then heat the allen wrench with your soldering iron as close to the form as possible to conduct the heat to the core.  Try applying heat for about a minute and then gently try turning the wrench (use pliers to protect your fingers from the heat and don't use much force).  If it is still stuck try another couple of minutes of heat.

No guarantee that the procedure will work but I have used it to free stuck cores in Heathkit SB series front end coil forms.  If you do get it loose pull it all of the way out and check for cracking.  If cracked then discard, it it is good clean the threads (core and form) and reinsert.

I have been lucky I guess, the only HQ problems I have had is with those open mica caps used in the HQ-170/180 transformers.

Rodger WQ9E

[k1pjs]

Thanks W3JN and WQ9E

73,

k1pjs

[k1pjs]

update....disassembled the transformers and found the wires broken. Re soldered and epoxy body back to base. Receiver now working.

K1pjs

[WQ9E]

Great! Always nice to hear of a success story.

Rodger WQ9E

[Todd, KA1KAQ]

Thanks W3JN and WQ9E

You couldn't have gotten two better guys to help you.

I'm curious, John - this isn't the first I've heard of it, but are the frozen slugs an issue mainly with the newer HQ rigs? It never seemed to be an issue for me with the old big box receivers like the HQ-120/129, 150 or Super Pros. Maybe I've just been lucky?

[w3jn]

Yeah, the cheaper and later Hammarlunds have the problem.  Ferrite slugs needing a hex tool and most of the time they're either seized or busted.

[N3DRB The Derb]

I got a stash of these at the richmond hamfest brand new in the tubes, 30 43 of them, all sizes, shapes, hex head, etc.  If anyone ever needs any, post a pic of the dead one or the fragments and I'll match it up close as possible and send it to youse. 

[KM1H]

The earlier HQ's and SP's used a slug with a threaded rod attached that exited the can. There was no physical contact to the coil form.

Ive used a trigger controlled propane torch to heat the Allen wrench for the other slugs. If you use the long Allens you can keep heat on them while applying gentle force with pliers. Frozen slugs is a real PITA with Heath products and house radios.

Carl
KM1H

[W3SLK]

Carl said:

Frozen slugs is a real PITA with Heath products and house radios.

Amen to that! I had a SoB-401 that the drive coils seized up on. I wish I had though about some of the ideas here.