15-10-2016, 02:56 PM
I have now done quite a lot of work on it. I cut three holes in the side, and inserted an octal socket, and two 4mm sockets. The 4mm sockets go to the LT supply. Seven of the pins in the Octal socket go to the corresponding pins on the original large 9-pin socket, the wiring of which has not been disturbed. A coupling box has also been made with and octal plug on one end of the lead (Old EF39 base). The 4mm sockets on the box are: Top row left to right: D1, D2 and A2. Bottom row, left to right: Cathode, Grid 1, Grid 2, Anode. I made up 6 jump leads with 4mm bananas on one end and 2mm bananas on the other. These join my home-made valve-holder panel to the Avo valve tester main unit. G3 can be linked to the cathode on the lower black terminals on my valve-holder panel. Initially, I found the filament volts too high. The mains setting was on 220V, so I moved it to 250V, and that corrected the filament volts. The anode and screen voltages are rather higher than those shown in the switch positions. As I am not able to select exact anode and screen voltages, I am not sure, at the moment, how accurate the test is! So far, everything I have tested is showing in the red. I will have to investigate further. Tracing the various connections on the 9-pin socket was a surprisingly tedious and long-drawn-out job.
Bob
Bob
