The 6SL7GT is a medium impedance double triode with high gain and superseded the 6SC7. It featured separate cathodes and was designed for use as AF voltage amplifiers, phase splitters and where required as a cascade amplifier of very high gain.

The makers name is not visible but the octagonal surround to the Type designation logo is typical of RCA.

The wide glass tube envelope is 28 mm in diameter and, excluding the IO base pins, is 62 mm tall.

References: Datasheet, ¹⁰⁴³, ³⁰⁰² & ¹⁰⁴⁰. Type 6SL7GT was first introduced^¶ in 1942.

 
Pin Connections

IO	1	2	3	4	5	6	7	8
	g1(2)	a(2)	k(2)	g1(1)	a(1)	k(1)	h	h

 
Absolute Maximum Operating Conditions^¶

Triode	Vh	Ah	Va	Vg	mAa	ra	gm	μ
	6.3	0.3	250	-2	2.3	44,000	1.6	70

Thanks to Frank Philipse for supplying the above PDF datasheet

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