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Heatercathodeshort · 23rd Feb 2021, 2:40 pm

An O/C in the frame linearity feedback loop can produce very high pulse voltages between the anode pin and heater of the frame output valve.

Paxolin was a great invention for the radio trade but could break down with spectacular effects. The GEC IF power supply plug in the 300 series the early symptoms of which was a low level crackling on sound followed a few weeks later by a massive crack of H.T. to the earth/grid pins of the B9A plug. The radio/chassis plug in the Ekco TS105 series suffered a similar fate.

EMI employed valve holders that they probably picked up on the street corner. They were very low quality and suffered heavy losses in TRF and Superhet I.F. strips. The HMV 'Highlight' series is a much better chassis than the 1807 series. They work quite well once you sort them out. Regards, John.

23rd Feb 2021, 2:40 pm	#8
Heatercathodeshort Dekatron Join Date: Jun 2005 Location: Warnham, West Sussex. 10 miles south of DORKING. Posts: 9,147	Re: Self Igniting Valve Holder! An O/C in the frame linearity feedback loop can produce very high pulse voltages between the anode pin and heater of the frame output valve. Paxolin was a great invention for the radio trade but could break down with spectacular effects. The GEC IF power supply plug in the 300 series the early symptoms of which was a low level crackling on sound followed a few weeks later by a massive crack of H.T. to the earth/grid pins of the B9A plug. The radio/chassis plug in the Ekco TS105 series suffered a similar fate. EMI employed valve holders that they probably picked up on the street corner. They were very low quality and suffered heavy losses in TRF and Superhet I.F. strips. The HMV 'Highlight' series is a much better chassis than the 1807 series. They work quite well once you sort them out. Regards, John.