Beautiful Hickok Western Electric KS-15750-L2 tester, completely restored, calibrated, with custom digital plate current meter.
Free shipping in the continuous 48 states. Tester has an extended limited warranty of 12 months for the new owner provided the tester is not opened which voids the warranty and good practices are followed such as testing for shorts FIRST.
1) Comes with CD copy of the operation manual for both the L1 and L2 models.
2)The tube being tested is a 6L6GC showing both gm on the main meter and the plate current at the same time. Match your power tubes as a manufacturer or distributor would by plate current.
3) Scope pictures show the 83 and 5y3 tubes being fine tuned for equal output so there is no gm offset to the readings. Note how far off the pulsed were before the tubes were balanced. The wide peaks are the 83 tube, narrow peaks the 5Y3. When these tubes are not balanced the gm can be higher or lower than actual, and the higher the bias the worse the offset becomes.
4) The digital meter has an independent power supply so there is no parasitic influence on the tester or the tube.
5) The case has been repaired for as many dents removed from the aluminum as possible, repainted, and new hardware installed.
6) The KS series is fundamentally the same as the Hickok B/C, but with extended gm ranges for testing Western Electric tubes.
Finally you can match up tubes the right way, by plate current. Even preamp tubes, because unlike an analogue meter, you see the current in 10th of a milliamp which is what you need for such tubes as a 12ax7, 6dj8, 6sn7 so you know how well the sides are matched up for power output that has bite, that grip on the dynamic high passages without overloading distortions. You can also see the gm, for the ability to resolve low signals, those soft passages, matching the Gm of the tubes will give you maximum low signal linearity. . If you use a moving coil phono cartridge or have phase splitters, you want better current matching than for driver tubes.
For power tubes, you can match so there is no residual magnetism left in the output transformer which muddies both the high and low frequencies, and increases the distortion products. Want a tight grip on the music, then match for high current, Like a more relaxed sound that a tube such as a RCA black plate gives, then match for lower plate current. And again as with preamp tubes, matching the Gm of the tubes will give you maximum low signal linearity."
All this work was done by C.G.Industries in Florida, in March.
Note: there are many who believe that solid state replacements for the 83 and 5y3 tubes is a great idea. That is fine, to each his own. Scope traces say otherwise, the attack and decay of the pulses are not the same, the SS units are hard and there is overshoot or ringing.. There is also the issue of loading on the transformer that is not duplicated by the solid state units even if they have resistors to mimic the tube heaters...it is just not the same either. While tested tubes may give results that seem the same, the very way the tested tube is in the circuit is not treated the same. The last point is the chance of burning out the screen or plate windings of the primary transformer because the solid state units are unforgiving if there is a short, and in the snap of your finger the winding is burnt (the 83/5y3 tubes limit the current, the SS units do not). Keep the 83 and 5y3 tubes, they last for decades, and reinventing the wheel is not always the best idea.
Shipping for the 48 states is flat 50. Other destinations is an estimate, but not over this estimate. Reasonable offers can be considered.