[Test-Equipment] B&K 707 tube tester

[Richard Keller]

Have just gotten a beauty, both appearance and working. Do not understand the "B&K
patented automatic line voltage compensation" and would like an explanation of it
theoretically. I see nothing  in the schematic of the primary other than the winding and
the power plug plus fuse and on/off switch.
To what are they referring and is it a legitimate claim? Using a variac and changing the
supply voltage causes a drop in primary voltage, simple as that. Two secondary windings
are tapped with a 3-resistor series circuit. I see nothing in the other secondary windings
out of the ordinary.
Thanks and 73, Dick KF4NS
St. Petersburg, FL 33714 USA
Keep the glow!