Original #27 tubes (227, 327) in globe/pear style bulb shape from late 1920s to early 30s. The 27 was introduced in 1927 in this glass style and was one of the first indirectly heated cathodes. The DeForest 27 is a bit rare.
Item Tag: 2 Tubes
PAIR NOS JAN GTE / Sylvania 12AT7WC TUBES, Closely Matched, Tested, #11
Closely Matched. Power tubes like the 6L6 are tested only with the 686 which includes plate current (Ip), shorts and gas tests. Tested on Heath TT-1A for Gm, shorts and gas. See photos for Gm results.
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Pair, RCA Radiotron Type 5814A Radio/Audio Tubes, NOS
One tests at 110% of the specifications for emission Em, and 109% of the specifications for mutual conductance, Gm on one plate. The other plate tests at 100% Em and 100% Gm. The second tube tests at 110% Em and 109% Gm on on plate and 112% Em and 109% Gm on the other plate.
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GE JG 6072A Tubes Two Mica Short Black Ribbed Plate Halo Foil Getter NOS Pair
Up for sale is a pair of GE JG 6072A double mica short black ribbed plate with halo foil getter NOS in original boxes.