You are bidding on (1) RCA USN CRC 6AC7 electron tube, made in the USA in the 1950's.  We got these tubes with a large lot we purchased and all have been tested on an Amplitrex AT-1000 digital tube tester.  The test results were printed and are attached to the boxes. 

All our tubes are tested and guaranteed by us; we only test tubes on one of our quality calibrated mutual conductance testers, NEVER on an emissions tester.  The testers we use are Phil Frakes's Bitmatic computerized Cardmatic testers from Tubesontheweb, the specific models are Western Electric KS-15874-L2's which were made for Western Electric by Hickok; we currently own two of these testers.  Our backup testers which we use occasionally are military TV-10D/U's.  For specialized tests, we employ one of our VTV Dual Triode Characterizers (for preamp tubes) as well as a Maxi-Matcher (for power tube matching).  Tubes are guaranteed for 90 days, refund or replacement our choice. Thanks for looking at our auction and be sure to check out our other auctions for other tubes that may be of interest.  (lot epe1004, s-3850)