Sylvania 7F7 Vacuum Tube Sylvania 3E6 NOS NIB Both tubes have thin cracks

Both tubes have thin cracks in their bases

meaning you need to indicate the quantity you want

(New US-made 7408s typically test with plate current from the mid-teens to mid-30s with transconductance from 2300 micromhos or so

This new old stock-TESTING matched pair of Sylvania 6SJ7s was tested on our Paul Hart-calibrated TV7/U for shorts

each with two rectangular holes

Sylvania 7F7 Vacuum Tube Sylvania 3E6 NOS NIB Both tubes have thin cracksThis Sylvania 7F7 was tested on our Paul Hart calibrated TV7 U for shorts, gas and transconductance. There were no shorts or gas. It measured 42 44 where minimum (65%) is 33 33 and 100% is 51 51. I have played it in my Cern Audio phono pre preamplifier as a 6SL7 substitute (with an adapter, not included) and it sounds outstanding. It is dead quiet when the preamp is muted and has excellent frequency response, sound staging, and dynamics It is somewhat