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G8UWM-MildMartin · 24th Mar 2013, 5:59 am

Hi Mike,
R27 (2K7) and R2 (120K or 100K ) are the only resistors I know of that need to be more than 0.25W.
For tolerances, R12's can be calibrated out, but R13 might be worth going to 1%.
Tolerances on R32-41 (twice!) for the Anode & Screen volts may tend to average out and it's debatable how critical the tolerances on the individual settings are anyway bearing in mind the tolerance on the zeners ZD1-7.
Best regards,
Martin.

24th Mar 2013, 5:59 am	#780
G8UWM-MildMartin Heptode Join Date: Jan 2004 Location: Stockport, Greater Manchester, UK. Posts: 827	Re: The "Sussex" Homebrew Valve Tester. Hi Mike, R27 (2K7) and R2 (120K or 100K ) are the only resistors I know of that need to be more than 0.25W. For tolerances, R12's can be calibrated out, but R13 might be worth going to 1%. Tolerances on R32-41 (twice!) for the Anode & Screen volts may tend to average out and it's debatable how critical the tolerances on the individual settings are anyway bearing in mind the tolerance on the zeners ZD1-7. Best regards, Martin.