03-22-2015, 01:48 PM
I made up a SS 80 with a couple 2.5A 1KV diodes. That brought the B+ up to around 320, that helped.
I finally have the remote receiver working with good (I think) sensitivity. I can trigger the thyratron with a -34dB input to the terminals. It will stay triggered down to -41. It was tricky to get it right, as the impedances on the grids of the 87 and the 6J7 (I'm temporarily using a 6K7) seem to be quite high, and even my scope probe loads them to a point they won't properly tune. I ended up feeding a +10dB signal in and getting the thyratron to fire, then backing the level off till it extinguished. I then tuned the first stage until it fired again then backed the level off till it extinguished again. Lather/rinse/repeat until I found what appears to be the best gain.
Now the next fun part. The stepper does not work reliably. This could be because I'm not able to send it properly spaced pulses until I get the Mystery Control working. We shall see.
The final chassis issue I have not wanted to deal with because it's going to be a total PITA is the volume control. This one has issues. Toward the lower end, it acts like a typical old volume control with either dire need of cleaning or a completely worn out trace. The volume jumps around as well as the timbre and the amount of distortion. If I find a sweet spot where the thing makes proper contact, it sounds great, but in the meantime it crackles and just makes very unpleasant noise. Once it's past this bad spot on the way up, it works fine and sounds great (but loud!!) This one of course is far more problematic to clean because it moves so slowly as you run the motorized volume up and down. I shudder at the thought of having to replace that control...
I finally have the remote receiver working with good (I think) sensitivity. I can trigger the thyratron with a -34dB input to the terminals. It will stay triggered down to -41. It was tricky to get it right, as the impedances on the grids of the 87 and the 6J7 (I'm temporarily using a 6K7) seem to be quite high, and even my scope probe loads them to a point they won't properly tune. I ended up feeding a +10dB signal in and getting the thyratron to fire, then backing the level off till it extinguished. I then tuned the first stage until it fired again then backed the level off till it extinguished again. Lather/rinse/repeat until I found what appears to be the best gain.
Now the next fun part. The stepper does not work reliably. This could be because I'm not able to send it properly spaced pulses until I get the Mystery Control working. We shall see.
The final chassis issue I have not wanted to deal with because it's going to be a total PITA is the volume control. This one has issues. Toward the lower end, it acts like a typical old volume control with either dire need of cleaning or a completely worn out trace. The volume jumps around as well as the timbre and the amount of distortion. If I find a sweet spot where the thing makes proper contact, it sounds great, but in the meantime it crackles and just makes very unpleasant noise. Once it's past this bad spot on the way up, it works fine and sounds great (but loud!!) This one of course is far more problematic to clean because it moves so slowly as you run the motorized volume up and down. I shudder at the thought of having to replace that control...
