8056

Nuvistor 8056

The 8056  (P/N 154-0417-00) is a low-voltage Nuvistor triode vacuum tube with a 6.3 V heater.

It is used in the 422, 502, early W, 1S1, 3A7, early 3S3, 3T4, 5T3, and 10A1. It can sometimes be replaced with a MPF102 FET.

The 8056 has a maximum plate-to-cathode voltage of 50 V. Contrast this with another Nuvistor triode, the 7586, which has a maximum plate-to-cathode voltage of 110 V (however, one of the 8056 test conditions for 157-0099-00 puts 100 V on the plate.)

The 7586 and 8056 have the same pinout, but the two tubes are not interchangeable since they have different voltage ratings.

For example, in the front-end cathode followers of the 3A1, the plate voltage of the 7586 tubes, V113 and V123, is 55 V, and possibly a bit higher during warm-up. This exceeds the maximum plate voltage of the 8056, unless the 3A1 is modified for lower front-end plate voltages.

Aged/Checked/Matched Pair Details
Used in	Tek Part#	S/N Range
502, W, 3A7, 10A1	157-0099-00	All

Reference:

Tube aging procedure / Selection and checking procedure

Links

• RCA 8056 Datasheet (PDF)
• Siemens 8056 Datasheet (PDF)
• RCA Nuvistor Reference (PDF)
• 8056 @ radiomuseum.org

Some instruments using part 8056

Instrument	Manufacturer	Class	Model	Description	Introduced
10A1	Tektronix	Plug-in	10A1	Differential amplifier plug-in	1965
1S1	Tektronix	Plug-in	1S1	1 GHz sampling system	1965
3A7	Tektronix	Plug-in	3A7	Differential amplifier plug-in	1965
3S3	Tektronix	Plug-in	3S3	Dual-trace sampling plug-in	1963
3T4	Tektronix	Plug-in	3T4	Programmable sampling sweep plug-in	1965
422	Tektronix	Oscilloscope	422	15 MHz portable dual-trace scope	1965
502	Tektronix	Oscilloscope	502	1 MHz dual beam differential scope	1958
5T3	Tektronix	Plug-in	5T3	Timing plugin	1965
W	Tektronix	Plug-in	Type W	8-23 MHz differential comparator	1965