Voltage readings too low (first build)

[Thomas]

Just finished my two stroke build using a 125ESE and one 12ax7 (thanks to the revised TAN 1.13.2011 revised 1.0 schematic). I checked voltage readings against D.Hunters book and mine are low. Perhaps I should look into smaller PT dropping resistors?

Tube.   Pin.   Expected vdc.   Measured vdc
6v6.        3.       340-360.               332
12ax7.     1.       140-160.               100
12ax7.     6.      140-160.                96

[Thomas]

Figured it out. The original target values from Daves book expect a 325v power feed. The revised schematic and layout are using 275v, which I adopted. This is why its lower

[Andy]

Sorry this is so late! Glad you figured it out.

What Power Transformer are you using? For our kit, we are using the Hammond 290AX which is 325V.

[Author]

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