by Shannon Parks » Mon Sep 19, 2011 6:35 am
Project News:
- I stripped the Hammond end bells and the Stancor choke with acetone. I felt like I needed more uniformity with the iron complement, so I also prepped the Edcor output bells with a green scratchy and then wiped down with acetone. All these were then painted with Hammertone black. Looked sharp, and I'll post pics.
- My ST-shaped 6L6GAs have pin 1 populated on their socket and they needed to be strapped on the PCB. I put wire jumpers between pin 1 and pin 8 on the PCB at V2 and V3. I was worried that if I had put this in the layout I might have an unintentional problem with 1626s, but I probably should have just done it. Note that this mod needs to be done for other tubes like EL34s and KT88s, too.
- My Stancor choke was dodgy, with an intermittent open. This caused very large voltage spikes as it acted like a large voltage booster. It took out one of the caps.
- I replaced the Stancor with a C354 and changed all my power supply caps. I changed the input cap to a 16uF, 600V chassis mount.
- Unfortunately, I'm still not getting the voltage drop I want. These tube rectifiers heat up so fast that I can have B+ soaring much higher at turn on than I'd like (>500V). This transformer - a 274BX - just won't work.
- Instead of getting a lower VCT tranny, I'll just revert back to the originally spec'd PA774 clone from Edcor and scuttle the tube rectifier. C'est la vie. At least I can now run my 1625s.
Shannon