[John L Stewart]

Here is a different kind of test on the PP 6V6 AB2 amp that I posted a while ago. And an updated schematic. The PS is a Hammond 271X into a FW CT, 1N4007s into a PI filter of 8 microF, 5H & 100 microF for the +ve side. There is also a –ve supply using 1N4007s on the same HV winding into another PI filter of 10 microF, 1.5K & 10 microF. The lid is held on for the –ve side by VR150 gas regulator. The OPT is a Hammond 125E Universal.

The 6V6 screen leads go to the +ve supply. You can connect the dots.

From that one might think not to much is possible but they would be wrong. My objective with this exercise as I had previously stated is to try some different things. That is, discover what is possible in a vacuum tube amplifier with low cost parts. It is well known that by throwing unlimited resources (money & time) at a project that most anything is possible. That is not my intention here!

There are many tradeoffs in any system. It is the designer’s task to separate what is important from what is not. In the real World market the end product must be competitive.

The trace shows what happens to the +ve supply under pulsed conditions. The top marker indicates 10 watts. The red trace is the one KHz test signal, pulsed. The blue trace is the B+ supply at the 6V6 plates. The pulse rep rate is about 14 Hz.

How did I do this? I will post that info later.

Cheer to all, John