Dismantling a "Microphone, Hand No. 8". . .

[G6Tanuki]

. . . as used on a range of WWII-era Army radios: my question being - on the bottom of these, where the cable exits the handle, is the bush the cable comes out through supposed to unscrew? It has 2 flats on it which would support the idea that it unscrews but on mine it appears this bush is glued in rather firmly.

--G6Tanuki

[Packhow75]

Yup - they unscrew.

[G6Tanuki]

Originally Posted by Packhow75

Yup - they unscrew.

Thanks. I was wondering how the crumbled red fibre 'cord grip' washer I removed through the junction-box-plughole got in there. I'll apply a bit more twist with the spanner - and maybe try running it under the hot tap.

[Packhow75]

If you break it - I probably have a spare somewhere - though finding it will be the biggest challenge at the moment.

Tim

[G6Tanuki]

Originally Posted by Packhow75

If you break it - I probably have a spare somewhere - though finding it will be the biggest challenge at the moment.
Tim

Thanks for the offer. I'm hoping that some heat will ease off the offending adhesive.

[The mic is destined to feed - through a suitable transformer - a single-ended 6L6 which should provide enough audio to modulate another 6L6 serving as xtal-oscillator/PA: I'm doing a budget re-creation of the RCA AVT-15 aircraft transmitter from the 1930s].

[Glowingtubes]

Drop a little liquid paraffin wax on it, works great on these sort of threads. After removing wipe off with paper towel.

Glo

[G6Tanuki]

Originally Posted by Glowingtubes

Drop a little liquid paraffin wax on it, works great on these sort of threads. After removing wipe off with paper towel.
Glo

Thanks for the tip! I've currently got the handle-end of the microphone where the threaded bush fits soaking in water in the hope this will soften the glue (and it most definitely is deliberately-applied glue not just an accretion of 60 years of crud).

If thay doesn't help I will try some warmed paraffin-wax to see if that will soften things enough to let me unscrew it.

--G6Tanuki

[AC/HL]

I'd hazard a guess at Shellac or some sort of varnish if it's original MOD.

[radiotechnician]

Here is a thumbnail of the cord grip of the Hand No 7 microphone.
unscrewed to show the length. Amazingly I did find it.

Finding the others, Nos 3, and 8, that are here will be a bother.

[G6Tanuki]

Thanks Steve. My threaded-bit is still soaking in the water, the glue sahowing no signs of dissolving.

I am thinking of trying to soak it in Meths next.

--G6Tanuki

[Paul Adams]

I seem to recollect, when I was at an electronics company back in the 80’s, they used to encapsulate everything in epoxy resin, and a well know brand of a fizzy drink C*ca-c*la used to soften the material.

And if it doesn’t work you could always have a refreshing drink

Paul.

[G6Tanuki]

Hadn't thought of using said fizzy-drink for this purpose; I don't normally have the stuff in the house but am prepared to buy a can of "Value" Cola from somewhere to see whether it works.

--G6Tanuki.

[G6Tanuki]

Result! After a month of soaking in methylated spirit I put an open-ended spanner on nthe flats, and pushed.

There was a worrying crack - then it unscrewed.

You can see the remains of the brownish glue still in the threads.