4 US-Made 6SF7 Vacuum Tubes Valves Lot Of Four GM Delco Zenith This matched trio of Raytheon

This matched trio of Raytheon 5Z4 rectifier tubes were tested on our Paul Hart-calibrated TV7/U for shorts

5 standard deviations of 4000 micromhos)

The pressing is quite-quiet with little surface noise and only the occasional pop and tick

Transconductance measured 42/31 for Tube One and 44/31 for Tube Two where minimum (65%) is 30/15

These tubes have excellent silkscreening

4 US-Made 6SF7 Vacuum Tubes Valves Lot Of Four GM Delco Zenith This matched trio of RaytheonThese 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