[davemc]

Thanks. According to Riders, the 37-660 transformer measures 700 ohms total. My original is open, unfortunately. The Utah 5999 measures 419 ohms total. I do not know what that implies. Perhaps the original has higher inductance, and thus perhaps more bass or less distortion. The owner just wants it to work, so I guess I should not worry.  I plan on using 10000 ohms for the plate load (6F6 push-pull pentode) and 2 ohms for the secondary (measures 1.2 ohms DC). So I am looking for a ratio of about 70:1 I suppose. I use my old HP200A audio generator to drive the primary at about 10 volts at 500Hz and look at the voltages on the various taps.