General Radio Vacuum Tube Bridge
This is what we use for special testing and matching of power tubes.
Plate power for this bridge is provided by a Kepco 1520B power supply 0-1500VDC @
200ma. Screen power is provided by a Kepco 605 power supply which supplies 0-600VDC
@500ma and a negative bias voltage of 0-150VDC. Also used is an HP 651B oscillator,
HP 5245 counter, Dytronics 717S AC Null Detector, and Krohn-Hite UF-101A Amplifier.
With this setup, I can meausre transconductance, plate resistance and amplification factor
to 3 signifigant digits. Most importantly, I can match output tubes at the voltages
they operate at in the circuits they are used in. This assures a good match.
Also, I can test tubes such as 211's, 845's etc. that cannot be tested on a standard tube
This tester is used at our testing lab and is not for sale,