SYLVANIA 6F8G / VT-99 – MATCHED QUAD 4 PCS
GRADE: PLATINUM SERIES | VINTAGE NOS WW2 US ARMY SIGNAL CORPS
U.S. Army Signal Corps (VT-99)
Black Coated Glass
Black Base
Top Cap Triode
6SN7 Equivalent
New in Original Government Box
Amplitrex AT1000 Tested
Up for sale is a closely matched quad (4 pieces) of WWII-era vintage Sylvania 6F8G / VT-99 dual triode vacuum tubes, brand new in their original US Army Signal Corps military contracting boxes . Made in the USA, these iconic tubes feature protective black coated glass shielding, crisp base stenciling, top grid caps, and robust black bases. Electrically equivalent to the famed 6SN7GT (when used with a top grid cap adapter), the 6F8G is revered by audiophiles worldwide for its incredible soundstage depth, silky smooth treble, and lush holographic midrange.
As shown, all four tubes have been thoroughly tested on our laboratory-grade Amplitrex AT1000 tube tester. Plate current (Ip) and mutual conductance (uMhos) measurements for both internal triode sections alongside percentage performance ratings relative to nominal specs are detailed in the table below.
| Serial No. | Triode Section | Plate Current (Ip) | Transconductance (Gm) | ||||
|---|---|---|---|---|---|---|---|
| Ref Spec | Result | % Ip | Ref Spec | Result | % Gm | ||
| SR.NO. 1444036 | Triode 1 | 9.0 mA | 7.8 mA | 87% | 2,600 µMhos | 2,700 µMhos | 104% |
| Triode 2 | 9.0 mA | 8.6 mA | 96% | 2,600 µMhos | 2,700 µMhos | 104% | |
| SR.NO. 1444022 | Triode 1 | 9.0 mA | 8.6 mA | 96% | 2,600 µMhos | 2,700 µMhos | 104% |
| Triode 2 | 9.0 mA | 8.0 mA | 89% | 2,600 µMhos | 2,700 µMhos | 104% | |
| SR.NO. 1444845 | Triode 1 | 9.0 mA | 9.5 mA | 106% | 2,600 µMhos | 2,700 µMhos | 104% |
| Triode 2 | 9.0 mA | 9.4 mA | 104% | 2,600 µMhos | 2,700 µMhos | 104% | |
| SR.NO. 1444060 | Triode 1 | 9.0 mA | 8.4 mA | 93% | 2,600 µMhos | 2,700 µMhos | 104% |
| Triode 2 | 9.0 mA | 8.2 mA | 91% | 2,600 µMhos | 2,700 µMhos | 104% | |
Technical Note: Custom duties and taxes are the responsibility of the buyer in their country.
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