• WARNING: Tube/Valve amplifiers use potentially LETHAL HIGH VOLTAGES.
    Building, troubleshooting and testing of these amplifiers should only be
    performed by someone who is thoroughly familiar with
    the safety precautions around high voltages.

Help and suggestions for my project based on the Radford STA-35 schematic

56085

Disabled Account
2021-07-06 6:56 am
otl800.blogspot.com
Based on your last post, and before you got things corrected, the EL34's were connected as follows:

Heater: Like it should be.
Cathode & suppressor grid: Like they should be.
Control grid: Connected to about + 450 V.
Screen grid: Connected to - 57 V.
Anode: Connected to nothing.

I'm really puzzled that you blew a 1 A fuse in this situation, since it would need about 500 mA of control grid current per EL34 to do so.
 

Bonfigli

Member
2022-03-03 2:05 pm
Based on your last post, and before you got things corrected, the EL34's were connected as follows:

Heater: Like it should be.
Cathode & suppressor grid: Like they should be.
Control grid: Connected to about + 450 V.
Screen grid: Connected to - 57 V.
Anode: Connected to nothing.

I'm really puzzled that you blew a 1 A fuse in this situation, since it would need about 500 mA of control grid current per EL34 to do so.
I confirm that the el34s were connected as you wrote.

do you have any indication to give me on the measurements to be made with the oscilloscope and the function generator?