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Heatercathodeshort · 8th Dec 2018, 12:25 pm

Great write up and what an epic journey!
The CRM91 pre war tube is an odd one and was certainly 'wide angle' at 64 degrees, compared with it's post war replacement the CRM92 57 degrees listed as a replacement for the CRM91.

It is a short stubby tube and considerable difficulties could be experienced attempting to squeeze the 92 into a 91 chassis. Mazda gave very little information stating only that the bulbs physical dimensions differed from the original..

As far as I know it was not used post war. The 1947 Ekco TSC30 employed the 92 tube.

Peter mentions the appallingly short life of Mazda tubes at that time. There were numerous complaints from Murphy dealers writing in the Murphy Service News. Apparently Ediswan knew there was a serious problem but just stated that 'the situation should get better in the future'.

Murphy Radio were one of the first companies to supply a 2v CRT isolation transformer for the Mazda triode tubes used extensively in their receivers at 15/- [75p]. [1952] They were sold out within hours and a new batch had to be produced.
Regards, John.

8th Dec 2018, 12:25 pm	#8
Heatercathodeshort Dekatron Join Date: Jun 2005 Location: Warnham, West Sussex. 10 miles south of DORKING. Posts: 9,147	Re: 1938 Murphy A56V television restoration Great write up and what an epic journey! The CRM91 pre war tube is an odd one and was certainly 'wide angle' at 64 degrees, compared with it's post war replacement the CRM92 57 degrees listed as a replacement for the CRM91. It is a short stubby tube and considerable difficulties could be experienced attempting to squeeze the 92 into a 91 chassis. Mazda gave very little information stating only that the bulbs physical dimensions differed from the original.. As far as I know it was not used post war. The 1947 Ekco TSC30 employed the 92 tube. Peter mentions the appallingly short life of Mazda tubes at that time. There were numerous complaints from Murphy dealers writing in the Murphy Service News. Apparently Ediswan knew there was a serious problem but just stated that 'the situation should get better in the future'. Murphy Radio were one of the first companies to supply a 2v CRT isolation transformer for the Mazda triode tubes used extensively in their receivers at 15/- [75p]. [1952] They were sold out within hours and a new batch had to be produced. Regards, John.