01-05-2012, 06:59 PM
Alan wrote 'R12 varies the bias on V1 Grid'
...Not on the Trader sheet, Alan. The grid bias control is definitely R10 (mind you, it is on your circuit too). R12 on the Trader sheet is part of a a screen potentiometer. I suspect you are confusing Pye's numbering with that of Trader.
I have to admit that I haven't followed your main thread about the set so I'm not in a position to comment upon any other fault - I was referring specifically to the function of the combined volume/reaction control.
With the pot effectively shorted the bias will remain constant on V1 grid as the reaction is turned. I don't suppose somehow that the reaction winding could have been connected in reverse? That certainly would cause a drop in gain.
Watch out for the mazak that self-destructs.
-Tony
...Not on the Trader sheet, Alan. The grid bias control is definitely R10 (mind you, it is on your circuit too). R12 on the Trader sheet is part of a a screen potentiometer. I suspect you are confusing Pye's numbering with that of Trader.
I have to admit that I haven't followed your main thread about the set so I'm not in a position to comment upon any other fault - I was referring specifically to the function of the combined volume/reaction control.
With the pot effectively shorted the bias will remain constant on V1 grid as the reaction is turned. I don't suppose somehow that the reaction winding could have been connected in reverse? That certainly would cause a drop in gain.
Watch out for the mazak that self-destructs.
-Tony
