[sobell1980]

I took a quick peak at ridiculous o clock before work this morning regarding the HT. Feeding L17 the HT was 364 volts. The other side of L17 was 290v. So a voltage drop of 74 volts across L17. I'm a great believer in finding the root cause rather than sticking a dropper in to obtain the correct HT. Thinking about it today, I realised for powering up the set first time I used a low emission output valve, valve 4 which was just for testing. I realised I hadn't swopped it back for the known tested good one. I popped this in and measured across L17 again. A voltage drop of 96 volts across L17 giving a HT after L17 of 246 volts instead of 290 volts after L17. Changing v4 really had made a difference. Also operation of the tone control is much more noticeable effect than when the low emission test valve 4 was in place. I noticed that I got a high pitched squeal from V4 when tone control was used and hardly any difference could be heard in tone. With a known good V4 fitted, no strange valve noises and much, much better improved tone control.
I don't think the test valve is much good now after screaming it's nut under test with no negative grid bias etc it was really under pressure. But, it has served it's purpose and saved ruining another good valve. So my HT is now 246 v at V4 anode pin. I don't think I'm going to get it much more down than this without now fitting a dropper. The mains transformer is set on its highest voltage setting. Also the trader sheet quotes that the quoted valve readings were also taken with the mains transformer on its highest voltage setting using a mains voltage of 228 v ac. My mains was 240v ac so would this now explain for my slightly higher HT than the quoted valve readings? Many thanks.
Dave.