No, didn't know that there was wax under the black - interesting.

Not much of it relative to the black tar,
I mean a massive amount relative to what you'd find anywhere else.
Drilling into it dirties the wax with the black powder.
If I wanted the wax, I'd drill a couple of holes in the top of it.
It will still melt before the tar does.
You can probably still buy wax if you were inclined,
but I think one of these would set the caps shells for a whole radio.

I am proud


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Image Link

This was a practice for a valve cover that matters.
I did a makeshift chemical treatment lab, motorised jig
for turning while spraying, and fan forced baking oven with extraction.
and it's still only a can of spraypaint

Damn photo doesn't do it justice!
Pretty confident with surface rust parts now

Matte black does look good.

Might be worthwhile writing the CBG 81 number on it somewhere for future reference.

All of these photos with text on them is filed away for future reference

But if my new Hammond one doesn't fit this,
I'd be good to give this cup away, unless it meant I was supposed to get a lower wattage one.

I just didn't want to stuff up the valve sleeve on my first go painting for a while.

It was going to be dark brown, but the new power transformer said otherwise ;)

Does the audio transformer get hot?
I think the wax is the thermal conductor to the metal casing.
The wax would also store heat in a short time, and dissipate
it over a longer period of time.
For something out of sight like that,
it would probably be better to update and use a transfer compound now.

By filling the voids in the transformer, wax would help with heat transfer, but it main purpose is probably to keep moisture out to prevent corrosion.

They can get warm, but unless you run the radio at full blast for a long time it is unlikely to get too hot.

I seem to have started a vigorous discussion!!!

Thanks STC830, you've given me some confidence. Will dig out the article (from my collection of EAs under the house).

My transformer doesn't have a shell (I've taken some pix but will have to download them later). The pitch covers the core and the windings, with 4 lugs sitting proud. The pitch on the core flakes off quite easily, but the problem is the windings and the former. The pitch has formed a layer over these that doesn't seem to be able to be easily flaked off (Hi honey, can I use your oven?) I haven't found any wax but haven't dug deep.

I agree with STC830, the pitch was almost certainly a moisture barrier.

It's just the wax between the top of the core and the cup I was talking about there..
as an explanation for putting a bit of wax in it first.

If you do get up at midnight and heat it up, let us know

Re ovens

Have been accused of tainting the oven with smells a few times mainly drying spray paint. Since only dry the paint at about 50C, I think the smell sticks to the inside of the oven. A burst at 200C when the job is out seems to fix it.

re wax

If you are putting the wax there to hold the transformer off the bottom of the cup, would have to make sure that it doesn't melt and drop the transformer to the bottom when the pitch goes in.

re the EA article

Good stuff, but at one point they say that the secondary operating impedance can be estimated from 10 X primary winding DC resistance - does not make sense to me - think they meant to say secondary winding DC resistance.

Fredr, I was just wondering if you still have the B61B HMV portable.

I would like to know what type of emblem it has on the front, a picture would be great if possible (email).

I am at present restoring mine.

Did you get yours sorted?

Clive