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FERNSEH · 11th May 2020, 8:57 pm

Avoid using other RF pentodes than the correct GEC Z329 and Mazda 30F5 in the IF amplifier stages. Pin for pin compatible valves such as the EF80/Z719 and 6F23 have different inter-electrode capacitances which will have a bad effect on the alignment. OK to use plentiful EF80 type valves in the video amplifier, sync separator and line oscillator stages.

DFWB.

11th May 2020, 8:57 pm	#100
FERNSEH Dekatron Join Date: Mar 2005 Location: Gateshead, Tyne and Wear, UK. Posts: 7,444	Re: Fixing a GEC BT 302 Television Avoid using other RF pentodes than the correct GEC Z329 and Mazda 30F5 in the IF amplifier stages. Pin for pin compatible valves such as the EF80/Z719 and 6F23 have different inter-electrode capacitances which will have a bad effect on the alignment. OK to use plentiful EF80 type valves in the video amplifier, sync separator and line oscillator stages. DFWB.