This particular lot is for both a known value NOS 6L6 tube (which is the tube preferred by Hickok), and a known value NOS 6AX7 tube (tests exactly like a 12AX7 but with a 6 volt setting), to be used in the calibration process for a Hickok 533, 533A, 534, 600, 600A, 605, 800, 800A, 6000, 6000A, or TV-7 military Hickok or Hickok design-based TV-7 tester. Each tube will be mailed with its known value Gm reading labelled on it, and each tube is a high quality and very stable USSR military tube from their rocket programs, put through a stringent and technically sound program to produce a known value. The 6L6 is used to check calibration, and the 6AX7 is used after to check the bias potentiometer---if you get significantly different readings from the known value of the 6AX7 after calibration, the pot may be dirty or worn (very common in older testers).

These tubes can also be used to gauge the measured value of a Hickok or Hickok design tester not mentioned above (other Hickok testers have slightly different designs which may cause problems unless you are careful to take their idiosyncrasies into account). The tubes can also be used to compare another brand tester\'s readings with what a regular Hickok reads; I have no other brand calibration information, but this can be addressed at different sites on the Internet.

I will email the winner with scans of instructions for calibrating a 600 or 600A Hickok (as outlined in a 12/2/55 Hickok company bulletin on calibration), calibrating a 533 or 533A Hickok (as outlined in a 6/14/61 Hickok company bulletin on calibration), and the calibration instructions for a 6000 or 6005 Hickok (as outlined in a 2/25/60 Hickok company bulletin on calibration). Instructions for calibrating other models in the testers listed above can be viewed on the internet, but I don\'t offer them because I am not sure if they are copyrighted --- Google or Bing for what you want to make sure you get what you need.

Please read the description, look at the picture(s), and read the shipping, payment, and return policies. I request payment within three days of sale end. As a seller, I provide response after the buyer leaves response so that I know everything is complete. If there is an issue with your item, please contact me as soon as possible so that we can address it. International buyers are responsible for all customs fees, and American law requires that I declare the correct value on the customs forms. Other countries not listed, please contact me for cost, conditions, and availability.