[dtvmcdonald]

I bought a 368. I figured I could convert it to post-injection for nothing, using a dual-trace scope. I was right.

However, getting it to work was a bitch. This particular gizmo must have been
a very adequate tool in its day ... it has been very very heavily used up
until the late 70's, as it had a couple of Nichicon electolytics in it and the
areas around the dials were worn. Recapping the rest was easy.
One vernier mechanism was broken and the front had to be removed to get to it. Then it worked.
But the AGC system didn't work and the marker generator was flaky on the
top band The AGC problem was a completely open 4.7 meg grid resistor. The
flaky markers were caused by poor solder joints on the wires connecting the
variable cap and its coils.

To make a post-injection output I reversed the flow on the coax that
connects the sweep output to the marker generator panel jack and made the
circuit I attach. It works OK. You connect it to the second channel of your scope.
Values are quite non-critical, but you need very fast low capacitance diodes.