Hallicrafters Plate transformer

Discussion in '"Boat Anchor" & Classic Equipment' started by N6UH, Dec 1, 2018.

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  1. N6UH

    N6UH Ham Member QRZ Page

    Aside from the obvious, has anyone opened one of these transformers up or have experience of similar ones before I have at it with the torch?

    It's sealed at the bottom by this soldered plate:


    There is what appears to be a plug in the top left of this picture. Possibly where the oil was put in it?

    cropped transformer top.jpg

  2. W4KJG

    W4KJG Subscriber QRZ Page

    I don't think I'd open it. I may be wrong, but I believe it is filled with a toxic oil. I hope somebody can veryify my concern one way or another.

    This is from Wikipedia:

    "Polychlorinated biphenyls (PCBs) were formerly used as transformer oil, since they have high dielectric strength and are not flammable. Unfortunately, they are also toxic, bioaccumulative, not at all biodegradable, and difficult to dispose of safely. When burned, they form even more toxic products, such as chlorinated dioxins and chlorinated dibenzofurans. Beginning in the 1970s, production and new uses of PCBs were banned in many countries, due to concerns about the accumulation of PCBs and toxicity of their byproducts. For instance, in the USA, production of PCBs was banned in 1979 under the Toxic Substances Control Act."

    K2WH likes this.
  3. W9GB

    W9GB Ham Member QRZ Page

    Ian -

    Before you start, KNOW where the Hazardous Waste Locations are in South Florida.
    It could be a Electrical Potting Compound, often tar-based (brownish black) from that era (post WW2 to 1970s).

    IF 21st century potting is desired (after rewind or repair),
    I use the 3M Scotch-Weld Epoxy Potting Compund, DP270 (black or clear)
    Last edited: Dec 2, 2018
  4. N6UH

    N6UH Ham Member QRZ Page

    It's definitely oil as I can hear it sloshing about when I shake it. I'm fairly sure our local waste management facility does some hazardous collection/disposal activities so I'll check with them first. There's no indication that it contains pcbs but it's odds on it does. As I read the regulations there's no option to repair or rewind if the oil contains pcbs so that's the end of it.
  5. N2EY

    N2EY Premium Subscriber QRZ Page

    Is the transformer defective?
    W1BR likes this.
  6. KE0ZU

    KE0ZU Ham Member QRZ Page

    Thats out of an HT-45, AKA "Loudenboomer" amplifier.

    I too ask, is it defective? I presume so since you're wanting to open it.

    The oil may also be harmless mineral oil. It was used in a lot of big dummy loads.
  7. KP4SX

    KP4SX XML Subscriber QRZ Page

    If you hit it with a torch you can expect the oil to heat and expand. You know the rest of the story.
    Drill and drain before using the torch.
    W1BR and KD2ACO like this.
  8. G3YRO

    G3YRO Ham Member QRZ Page

    You expect him to take the oil on a plane over to to Florida?!

    If the transformer's faulty, I wonder what you hope to gain by taking it out of the can?

    Roger G3YRO
  9. KD2ACO

    KD2ACO Platinum Subscriber Platinum Subscriber Life Member QRZ Page

    G4LPL lives in Florida.
    KP4SX beat me to the punchline.
    The oil is likely mineral oil.
    If you drain the can and unsolder it. The problem could be a broken wire at the termination, not a difficult repair.

    On the other hand, if the oil is toxic, then one can drop a few levels down ala Dante. If an unfotunate soul heats the can without draining (venting) it, then that’s an 8th or 9th circle offense. :p
    Last edited: Dec 2, 2018
  10. N6UH

    N6UH Ham Member QRZ Page

    Yes. One side of the secondary to the ct is intermittently showing the same resistance as the other or OC.

    Correct or at least the plate power supply for it. It is currently 100% original and almost museum quality cosmetically.
    That's why I want to try and keep it that way if at all possible.

    There's an indentation in the top (2nd pic, top left) which I'm guessing is how the oil was poured in and then sealed. I'll sand off the paint later today and see if there are any indications as to how it comes out.

    Hope so! I wouldn't want to fall foul of the enviro-nuts when I open Pandora's box!

    That's exactly what I wanted to check out first before ditching the original and building a new one!

    KD2ACO likes this.

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