4 US-Made 6SF7 Vacuum Tubes Valves Lot Of Four

4 US-Made 6SF7 Vacuum Tubes Valves Lot Of FourThese four US made 6SF7 tubes were tested on our Paul Hart calibrated TV7 U for shorts, gas and transconductance. There were no shorts or gas. They tested as follows: 40 32, 65 28, 74 37 and 76 54 where minimum (65%) is 50 40. Most don't test great, but most should work in most circuits. WE HAVE SCORES OF THOUSANDS OF VACUUM TUBES. IF IT'S NOT LISTED, WE MAY HAVE IT. PLEASE ALSO SEE OUT ETSY SISTER SITE "LOWTECHTWOO" AND OR CALL OR TEXT US AT 202 372

It sounds very good with an occasional pop and tick audible in the pianissimo passages

I have played them in my Radio Craftsman RC2 monoblocks and they sound outstanding even though they test on the cusp

(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

new in box Sylvania 6AC7 tubes tested to spec on our Paul Hart-calibrated TV7/U

32 and 52 where minimum (65%) is 36 and 100% is 55

new in box Telefunken PCL81 tube tested to spec on our Paul Hart-calibrated TV7/U

44 and 50 where minimum (65%) is 30 and 100% is 47

These tubes have black

It measured 60 where minimum (65%) is 37

new in box milspec black plate GE JAN-6Y6GT / JAN-CG-6Y6GT tubes tested to spec on our Paul Hart-calibrated TV7/U

This matched pair of Philips Miniwatt PCF80 / 9U8 tubes was tested on our Paul Hart-calibrated TV7 for shorts