Dear Mr. Hagerman, I'm the freeloader who built January 07's DIY of the month Hagtech project. It's true, I used all my own scrounged parts, laid out and built my own turret board for the signal circuit. Still sounds bitchin but I have a question. According to the wiring diagram I pilfered, you settled on 6.1V on the filaments. What led you to this decision?
I didn't do a very good job of selecting R21, the filament supply's dropping resistor. As you know, low-value resistors vary enough from their spec that the resulting voltage on the heaters can vary a half-volt in a heartbeat. I checked it the other day (after listening with great joy for 8 months!) and it was pushing 7V. I had to dick around for two hours, installing various series and parallel combinations to settle it in at 6.1.
I'm using tubes from the 1940s and 50s. If you trimmed back the heater voltage to accomodate contemporary tubes (Russian, Chinese, etc.), perhaps bumping it back up to 6.3V would be a worthwhile experiment?
Thanks again for the great work. My Cornet has made more than one astute listener give me that, "you're kidding me," look. Tough to believe the homely green cake pan rocks like it does. You're the best!
