Hello--
I'm not sure whether this qualifies as my easiest-- or most difficult--
repair.
Years ago, I purchased a Kay Elemerics multiband sweep generator and discovered
that its swept-frequency output was nowhere near frequency-linear.
I swapped tubes (yes, it was that old) to no avail. Removing the chassis from the cabinet,
I noted that the underside was spotlessly clean, and every soldered connection sported
a little daub of red inspection varnish.
A couple of weeks went by and the schematic arrived in the mail. To generate a frequency sweep, a trapezoidal sawtooth waveform drove an Increductor (I *told* you this instrument was that old<g>).
I compared the wiring and discovered that the schematic showed the
Increductor driver tube's cathode connected to a bias resistor.
But it didn't. The red-varnished cathode connection went directly to ground.
Snipping the cathode-to-ground jumper restored the cathode
connection to its bias resistor and the sweep to linearity.
73--
Brad AA1IP
