Most of the work that [Ron] has done in the past with vacuum tubes and solid state electronics has been repair. At 59 years old, he finally put together his own stereo tube amplifier and we have ...

but tube amplifiers have a propensity for telling you they need a little bit of TLC at the worst possible times, and it isn’t always the easiest thing to repair a tube amp just before a gig.

However, with a tube amplifier, a VTVM could also show a very high resistance and still make good measurements. The Heathkit meter used a dual tube as an amplifier along with some input resistor ...