Siemens Telephone 356 - UK Vintage Radio Repair and Restoration Discussion Forum

TonyDuell · 16th May 2023, 3:54 pm

Am I right in thinking that a Siemens Telephone 356 is the same as a GPO Telephone 332?

I bought a Siemens 356 last week and spent much of the day repairing the dial. It's one of the older slipping-cam designs. It didn't return to normal because the mainspring was broken into several pieces. I've transplanted a dial mainspring from my spares box. Also the one-way clutch to the governor was stuck solid but responded to a squirt of propan-2-ol, being worked by hand until it freed up and then a drop of oil.

But is there anything I should be wary about if I assume this is a Telephone 332?

russell_w_b · 16th May 2023, 6:30 pm

According to the blurb from the Siemens Brothers and Co Catalogue 500/54 on Bob's telephone pages, the 356 is a 'Table telephone of the latest pattern, as standardised by the British Post Office.' The circuit looks identical too.

But that's not to say yours is. It may be tropicalised or an export model, in which there may be slight differences in bell impedance or ASTIC characteristics (say). My Siemens 366 wall-model has an ATM 24/C dial fitted and has a flat mouthpiece instead of the 'spit-cup' one.

Is yours physically identical to a 332 instrument?

TonyDuell · 17th May 2023, 5:06 am

As far as I can see it is physically identical to a GPO 332, but I've not put them alongside each other. It does have the 'spit cup' mouthpiece.

OK, I'l get a 332 off the shelf and compare them inside and out.

russell_w_b · 17th May 2023, 10:08 am

Quote:

Originally Posted by TonyDuell

OK, I'l get a 332 off the shelf and compare them inside and out.

Has your 356 got a paster diagram in it? I'm only mentioning all this because my Siemens 366 has a 0.5uF bell capacitor (part of the square-section block capacitor), and the 2uF section is used as part of dial pulse suppression cct. One of the original bell bobbins (Ringer 20A - Siemens' own designation?) was O/C so I replaced them with bobbins from a Bell 59A, but now I'm wondering if they were 500 Ohms?

I think my 366 may have been for use overseas, and wondered if your 356 was too. But I don't think yours will be terribly different from a 332 that would prevent it from working on the system. If there is anything different about it, would you put some photos on?

16th May 2023, 3:54 pm	#1
TonyDuell Dekatron Join Date: Jun 2015 Location: Biggin Hill, London, UK. Posts: 5,066	Siemens Telephone 356 Am I right in thinking that a Siemens Telephone 356 is the same as a GPO Telephone 332? I bought a Siemens 356 last week and spent much of the day repairing the dial. It's one of the older slipping-cam designs. It didn't return to normal because the mainspring was broken into several pieces. I've transplanted a dial mainspring from my spares box. Also the one-way clutch to the governor was stuck solid but responded to a squirt of propan-2-ol, being worked by hand until it freed up and then a drop of oil. But is there anything I should be wary about if I assume this is a Telephone 332?

16th May 2023, 6:30 pm	#2
russell_w_b Dekatron Join Date: Jul 2007 Location: Penrith, Cumbria, UK. Posts: 3,672	Re: Siemens Telephone 356 According to the blurb from the Siemens Brothers and Co Catalogue 500/54 on Bob's telephone pages, the 356 is a 'Table telephone of the latest pattern, as standardised by the British Post Office.' The circuit looks identical too. But that's not to say yours is. It may be tropicalised or an export model, in which there may be slight differences in bell impedance or ASTIC characteristics (say). My Siemens 366 wall-model has an ATM 24/C dial fitted and has a flat mouthpiece instead of the 'spit-cup' one. Is yours physically identical to a 332 instrument? __________________ Regds, Russell W. B. G4YLI.

17th May 2023, 5:06 am	#3
TonyDuell Dekatron Join Date: Jun 2015 Location: Biggin Hill, London, UK. Posts: 5,066	Re: Siemens Telephone 356 As far as I can see it is physically identical to a GPO 332, but I've not put them alongside each other. It does have the 'spit cup' mouthpiece. OK, I'l get a 332 off the shelf and compare them inside and out.