Can you guess this one? - Page 2 - UK Vintage Radio Repair and Restoration Discussion Forum

Restoration73 · 18th Jun 2015, 4:34 pm

Yes, McMichael 909 or 912 seem to have that dual chassis. I'm assuming it's a round CRT.

Heatercathodeshort · 18th Jun 2015, 6:10 pm

Yes! It is a McMichael T909 9" 'bookcase' console from 1949.
Compare this with the simplicity of the Ferguson 941T or the Bush TV12 from the same era. This looks very pre-war with it's over the top construction.
McMichael were the only TV company to employ the B7G based ECC91 as frequency changer/mixer.
The sound stages are double superhet.
I will gave a go at it sometime. It's in very good condition and a Mullard tube.
Well done! John.
[pic from radio and TV servicing]

HamishBoxer · 18th Jun 2015, 6:24 pm

Before I saw the power supply and with you saying large I thought that lethal mains derived Ultra 50,s console of which I have one of.

Restoration73 · 18th Jun 2015, 7:41 pm

Well the last McMichael I know of was 3011 or 3013 around 1966. I think the only name
that survived to the end of mono was KB (before ITT-KB)

FERNSEH · 18th Jun 2015, 9:15 pm

In 1984 the McMichael name was revived by GEC. An excellent range of Hirwaun made sets was introduced to the trade. Model numbers that come to mind were the C2085H and C2088H.
The rebranded product was called GECMcMichael. Evidently the McMichael division was the company that made industrial and military electronics.

Getting back to the McMichael 909. Now that is a magnificently over engineered receiver. Some of the circuits were quite extraordinary. The 909 and 912 are superhets and in fact as far as the sound is concerned these receivers are double superhets. The sound IF at the anode of 6J6/ECC91 frequency changer is 27Mhz, an unusual frequency. But that not the end of the story, in the 909 the sound IF is converted down to 2Mhz. This might make sense in the model 912 because this set has broadcast radio facilities. 2Mhz for TV sound and also for the radio. The sound IF amplifier is V14, an EF41 vari-mu pentode which also functions as an audio amplifier. The vision IF is 23.5Mhz.
Also noteworthy is the flyback EHT supply which employs a doubler circuit, two EY51 rectifiers. An EZ35/6X5 is used as a line damper diode.

After all this over engineering the model 512 employs a very simple and economical circuit. A mains transformer is used for the CRT heaters and to supply a higher HT voltage. A 0.3amp series heater chain supplies all the valves including the PZ30 HT rectifier.

DFWB.

PJL · 18th Jun 2015, 10:26 pm

Jon's brilliant website wins this one...Mullard, 1940's, known brand, then the location of the front controls sealed it.

18th Jun 2015, 4:34 pm	#21
Restoration73 Nonode Join Date: Jun 2013 Location: Surbiton, SW London, UK. Posts: 2,801	Re: Can you guess this one? Yes, McMichael 909 or 912 seem to have that dual chassis. I'm assuming it's a round CRT.

18th Jun 2015, 6:10 pm	#22
Heatercathodeshort Dekatron Join Date: Jun 2005 Location: Warnham, West Sussex. 10 miles south of DORKING. Posts: 9,147	Re: Can you guess this one? Yes! It is a McMichael T909 9" 'bookcase' console from 1949. Compare this with the simplicity of the Ferguson 941T or the Bush TV12 from the same era. This looks very pre-war with it's over the top construction. McMichael were the only TV company to employ the B7G based ECC91 as frequency changer/mixer. The sound stages are double superhet. I will gave a go at it sometime. It's in very good condition and a Mullard tube. Well done! John. [pic from radio and TV servicing] Attached Thumbnails

18th Jun 2015, 6:24 pm	#23
HamishBoxer Dekatron Join Date: Aug 2007 Location: W.Butterwick, near Doncaster UK. Posts: 8,935	Re: Can you guess this one? Before I saw the power supply and with you saying large I thought that lethal mains derived Ultra 50,s console of which I have one of. __________________ G8JET BVWS Archivist and Member V.M.A.R.S

18th Jun 2015, 7:41 pm	#24
Restoration73 Nonode Join Date: Jun 2013 Location: Surbiton, SW London, UK. Posts: 2,801	Re: Can you guess this one? Well the last McMichael I know of was 3011 or 3013 around 1966. I think the only name that survived to the end of mono was KB (before ITT-KB)

18th Jun 2015, 9:15 pm	#25
FERNSEH Dekatron Join Date: Mar 2005 Location: Gateshead, Tyne and Wear, UK. Posts: 7,444	Re: Can you guess this one? In 1984 the McMichael name was revived by GEC. An excellent range of Hirwaun made sets was introduced to the trade. Model numbers that come to mind were the C2085H and C2088H. The rebranded product was called GECMcMichael. Evidently the McMichael division was the company that made industrial and military electronics. Getting back to the McMichael 909. Now that is a magnificently over engineered receiver. Some of the circuits were quite extraordinary. The 909 and 912 are superhets and in fact as far as the sound is concerned these receivers are double superhets. The sound IF at the anode of 6J6/ECC91 frequency changer is 27Mhz, an unusual frequency. But that not the end of the story, in the 909 the sound IF is converted down to 2Mhz. This might make sense in the model 912 because this set has broadcast radio facilities. 2Mhz for TV sound and also for the radio. The sound IF amplifier is V14, an EF41 vari-mu pentode which also functions as an audio amplifier. The vision IF is 23.5Mhz. Also noteworthy is the flyback EHT supply which employs a doubler circuit, two EY51 rectifiers. An EZ35/6X5 is used as a line damper diode. After all this over engineering the model 512 employs a very simple and economical circuit. A mains transformer is used for the CRT heaters and to supply a higher HT voltage. A 0.3amp series heater chain supplies all the valves including the PZ30 HT rectifier. DFWB.

18th Jun 2015, 10:26 pm	#26
PJL Dekatron Join Date: Sep 2005 Location: Seaford, East Sussex, UK. Posts: 5,997	Re: Can you guess this one? Jon's brilliant website wins this one...Mullard, 1940's, known brand, then the location of the front controls sealed it.