4 US-Made 6SF7 Vacuum Tubes Valves Lot Of Four GM Delco Zenith perfectly-matched pair of RCA black

perfectly-matched pair of RCA black plate

O getter and an 805 ACP date / provenance code

Both are acid-etched

perfectly-matched pair of RCA 6K7 tubes were tested on our Paul Hart-calibrated TV7/U for shorts

5 standard deviations of 4000 micromhos)

4 US-Made 6SF7 Vacuum Tubes Valves Lot Of Four GM Delco Zenith perfectly-matched pair of RCA blackThese 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