Matched Pair General Electric GE 6SN7 6SN7GTB Vacuum Tubes Copper Support Rods NOS NIB

Matched Pair General Electric GE 6SN7 6SN7GTB Vacuum Tubes Copper Support Rods NOS NIBThis new old stock, new in box matched pair of GE 6SN7GTB dual triodes was tested on our Paul Hart calibrated TV7 U for shorts, gas and transconductance. There were no shorts or gas. Transconductance measured 76 86 for Tube One and 77 77 for Tube Two where minimum (65%) is 50 50 and 100% is 77 77. They have side O getters; tall bases; LV 188 5 and JU 188 5 date provenance codes, respectively; copper support rods; a round and square hole in each mica

and if it is

Transconductance measured 38/41 for Tube One and 42/41 for Tube Two (RCA-LABELED) where minimum (65%) is 32/32

1 12SK7GT/G

I am playing them in my Sound Craftsmen RC-2 monoblocks (as an "excellent" 6SN7 substitute according to Antique Electronic Supply's "Tube Substitution Guidebook") with "Hanson Conducts Ives

The dust jacket is excellent shape

It measured 36/39 where minimum (65%) is 18/18 and 100% is 28/28

These tubes have copious flashing

new in box United 15KY8A tube tested to spec on our Paul Hart-calibrated TV7/U

new in box GE 6CB6 / 6CB6A / 6CF6 tubes tested to spec on our Paul Hart-calibrated TV7/U

Unfortunately I cannot determine who manufactured it

new in box Philco number/type 35/51 tube tested to spec on our Paul Hart-calibrated TV7/U

nonetheless