This new old stock-testing matched pair RCA 6L6GB output tubes was tested on our Maxi Matcher 2 for shorts, gas and transconductance.  There were no shorts or gas. Transconductance measured:

Tube One:  26.5 milliamps / 2340 micromhos (RCA remnants remaining & 6L6GB on glass; unbranded base)

Tube Two:  24.7 / 2290 (RCA branded base with code 58-39; 6L6GB on glass)

Tubes tested with 400 volts on the plates and a bias of -48 volts. New old stock US-made 6L6s typically test with plate current from the mid-teens to 

mid 30s with transconductance from around 2200 micromhos.

Tubes have black plates, dual bottom D double bar getters, top radiators for cooler operation and longer tube life, crenelated round micas and tight on bases with no debris or rattling sounds.  Sound tested in our Musical Paradise shop amp (see pics).

Please Note:  6L6GB tubes can only be used for amplifiers rated for GBs.  If you use them in a 6L6GC rated amplifier you will destroy these tubes and we can not refund you.

Tubes ships via United States Postal Service (USPS) First Class Mail with tracking for domestic U.S. sale; Priority Mail is an option if you desire quicker 

delivery.  International orders ship via eBay International Shipping.

Package weighs twelve ounces (12 oz).

Please view my eBay store for other varieties of tubes.

Combined shipping always welcomed.

TUBES ARE GUARANTEED GOOD AND IN WORKING ORDER AT SHIPMENT.  TRANSIT VIA POST CAN DAMAGE TUBES.  THIS IS NO FAULT OF OURS BUT THE THIRD PARTY ENTITY THAT IS DELIVERING ITEM(S) TO YOU, I.E, USPS, UPS, FEDEX, YOUR NATIONAL CARRIER IF INTERNATIONAL, ETC. PLEASE INSURE THEM! WE CANNOT GUARANTEE FAILURES ON YOUR EQUIPMENT AFTER POWER UP AS THERE IS NO WAY TO ASCERTAIN HOW TUBES WILL INTERACT WITH YOUR ELECTRONICS; NOR IS THERE A WAY TO DETERMINE WHETHER THEY MAY HAVE FATAL FLAWS IN TUBES THEMSELVES!  THESE ARE USED VACUUM TUBES AND TIME MAY HAVE TAKEN A TOLL ON THEM OVER THE MANY YEARS SINCE THEY WERE MANUFACTURED. WE CAN ONLY TEST FOR THE PARAMETERS MENTIONED ABOVE IN ONE OR MORE OF THE FOLLOWING EQUIPMENT WE USE FOR MEASURING:  TV-7/U, JACKSON 648 & MAXI MATCHER 2.