OK..here ya go Myles-
I guess I need to read a primer on tube testing..
2-Marched Premium 12ax7:
Fully tested on a calibrated TV-7 conductance tester at 43/47 and 47/49 where 32 is good. Originally sold and labeled for the Sanborn Company.
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2-Matched RCA 5751 tubes (lo mu 12AX7 ECC83):
black ridge plates, 2 mica spacers, extra support rods between mica spacers and halo ring getters at the tops.
Tubes appear identical in construction!
Hickok TV-7B checked @ 42/41 39/44
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2-RCA 3-Mica Black plate 5751/ECC83
Test at 118/130, 120/130, on a EICO 667 Ttube tester.min:60
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2 NOS Mullard 12AT7WA CV4024(12AT7 ECC81):
These are the low noise CV4024 m8162 British Military version of the 12AT7, manufactured by Mullard in Mitchum, Great Britain, not the inferior Mullard re-issue tubes currently available!
Coded '654 R4D3' (Mullard Mitchum, 1984)
Pairs selected by factoring in both IP and Gm.
Gm tested at 3600/4500, 3900/4900. Min 2500, average new 3850 mho.
IP (plate current) 3.8/6.6, 4.1/6.4. Average new 3.7 ma.
Fully Tested on a Hickok 539C tester and guaranteed.