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Heatercathodeshort · 6th Oct 2017, 8:19 am

Don't be put off by this thread! This example was a basket case having been stored in very bad conditions with the complication of the modifications required for Band 3.

The BT2147 series, and this covers are very large number of models, is very straightforward and capable of excellent results with a good standard of reliability.

The only black hole is the flat faced GEC tube type 6505A. It tends to develop heater faults mainly lowering it's resistance together with an O/C cathode connection.

Being flat faced it is difficult to replace from a mechanical aspect with a conventional Mullard MW22-14/16/18 9" type.

This could possibly be overcome with the BT2147 due to the CRT faceplate being spaced a little from the implosion protection screen. The earlier BT1091 is almost touching it so no room for modification here.

The Mullard tubes ar also tetrodes requiring a first anode voltage of around 300v. No problem obtaining this potential from the chassis but they also require a much reduced focusing field needing shunts to be fitted across the focus magnet. [See my Ekco T164 restoration]

Other than the CRT difficulty no problems should be experienced.

I have the full service manual available should you require it.

My pet Orangutan 'Interlace' has been instructed to search all Forum friends vehicles for any Bakelite 'Oh what a lovely cabinet' models and direct their vehicles back onto the A29 or he may pelt you with duff U801's...

Regards as always, John.

6th Oct 2017, 8:19 am	#79
Heatercathodeshort Dekatron Join Date: Jun 2005 Location: Warnham, West Sussex. 10 miles south of DORKING. Posts: 9,147	Re: And the next one! a GEC BT2147 Don't be put off by this thread! This example was a basket case having been stored in very bad conditions with the complication of the modifications required for Band 3. The BT2147 series, and this covers are very large number of models, is very straightforward and capable of excellent results with a good standard of reliability. The only black hole is the flat faced GEC tube type 6505A. It tends to develop heater faults mainly lowering it's resistance together with an O/C cathode connection. Being flat faced it is difficult to replace from a mechanical aspect with a conventional Mullard MW22-14/16/18 9" type. This could possibly be overcome with the BT2147 due to the CRT faceplate being spaced a little from the implosion protection screen. The earlier BT1091 is almost touching it so no room for modification here. The Mullard tubes ar also tetrodes requiring a first anode voltage of around 300v. No problem obtaining this potential from the chassis but they also require a much reduced focusing field needing shunts to be fitted across the focus magnet. [See my Ekco T164 restoration] Other than the CRT difficulty no problems should be experienced. I have the full service manual available should you require it. My pet Orangutan 'Interlace' has been instructed to search all Forum friends vehicles for any Bakelite 'Oh what a lovely cabinet' models and direct their vehicles back onto the A29 or he may pelt you with duff U801's... Regards as always, John.