If you look at the end of the shaft carefully, it still has the circular lines from a cutting tool. A break will not look like that. Its only a matter of hrs since I attacked a piece of conduit with my lathe.

The round shaft is puzzling. The radio is advertised as being portable so that it would have been necessary for the accessory speaker to be often switched on and off as the radio was moved around. A round shaft is not adapted to this use since a knob can be attached only by a grub screw (not possible because of its short length), or by an interference fit. On this basis the key or knob, which probably came with the speaker, would perhaps be tapped on with a hammer to become a permanent attachment.
None of my references such as Lankshear's books is enligtening.

I have made an inquiry to another in the Radio Club that I believe has one. I am firmly of the opinion that the shaft is what it always was. This is the reasoning behind the asking if there is a drilling, through the shaft for a pin? Otherwise it's possibly a knob with a long neck & split with a spring to clamp it to the shaft. These horror stories break with regular monotony.

Drilling is not an action unheard of, as that is how some potentiometer's in my BWD CRO are joined to the their drive shafts. Of course one pot is faulty & the new one is going to need drilling exactly in the same spot: That wont be with a hand drill.

it's possibly a knob with a long neck & split with a spring to clamp it to the shaft.

That would be my guess as well, and would also explain why it's missing.

I am working on my Oz replacing capacitors and have noticed the circuit is not the same as the one in Silicon Chip.

http://archive.siliconchip.com.au/cms/A_100857/article.html

There is a coil with a resistance of 800Ω and bypass capacitor, 5μF in the cathode of the 43 to ground. This is similar to the audio output stage in my Astor Caliph PZ. Why use a coil and not a resistor.
Notice the SC radio does not have a speaker change over switch also. My radio looks original and it is serial number 3381, so it may be a late production. It will be interesting to see what Brad’s chassis reveals.

Just checked two radios at our Sound Presevation Museum, in Hobart.
And both have identical switch shafts, but no knobs or keys to operate the switch.
Perhaps this came with the extension speaker.
JJ

There would be good reason to cap the hole & not have a knob in it. One would be that some Goose would turn it onto extension speaker setting & not be able to work out why it was not working and worse, if the secondary (or the voice coil) goes, or is opened, the OP transformer can start "ringing". That produces EHT in the primary which often flashes over & will do neither valve, or insulation any good.

That’s interesting Marc, one of the two I looked at had the hole sealed with what looked like wax.
JJ

Photo uploaded to Post 20.

Later version of the Oz circuit.

I replaced the caps and have got it going. I have noticed the circuit is not as per the published schematic around the 43 output valve. The wiring looks original and if it was modified they must have done it in the 30's.

Has anyone else examined an Oz with the published circuit?

Should I modify the circuit back to the published schematic or draw a new schematic with the modification?

Glen on the The Real Bakelite and Antique Radio Face Book has posted a picture of the knob.

Glen on the The Real Bakelite and Antique Radio Face Book has posted a picture of the knob.

Maybe post a copy of the image here for posterity, and for those of us who have zero to do with Facebook.

Photos uploaded to Post 26.

Thanks Garyoz/Brad.

See also, Astor Mickey OZ circuit variations over the production period, 1933 – 1935.

https://vintage-radio.com.au/default.asp?f=2&th=914