Klausmobile Tube Tester Files

See also: 6S3Pi-E mil grade, 'civilian' 6S3P pages

Reflector (Saratov), 08/1985. Brand new in individual boxes with datasheet.

For DC and low frequencies, this tube is identical to 6S3P (all DC specs match). But while 6S3P has 7.4pF input and 2.2 pf grid-to-plate capacitances, 6S4P has 13pF input and 0.17 pF grid-to-plate. While plate assemblies between the micas are identical, there are visible diffrences:

Getter disk/ring is suspended on three posts (as is the case with 'E' suffix and no-suffix 'original' 6S3P and 6S4P).

Standard specifications per each triode
Parameter Maximum for 10000 hours * Operating Point Measured
Ua, V +150 150 145
Ug, V - (-1.5) -1.25
Ia, mA 20 15 14
Pa, W 3.0 (2.3) 2.1
Gm, mA/V - 15 (11..19) 18
Rp, kOhm - (3.3) 2.1
Mu, V/V - 50 (35..65) 39

* Original datasheet rates max specs for 10.000 and 1.500 hours, as long as glass temperature is under 150C (1.500 hrs) and 90C (10.000 hrs)

1. Full power curves. Interesting, grid current appears as is should around 0V on grid, but it turns on very gently so the current compression in positive grid zone is also not as dramatic as with other tubes up to +1.25V. Overall output voltage margin is narrow (50v peak-peak between 120 and 170V at plate).

2. 12mA closeup

3. 6mA closeup

4. Full power curves, normal 6.3V and low 5.0V heater voltage. No change in parameters except a 1/4V shift in effective grid voltage. Given the tube's high gain and transconductance, heater stability is essential - this 1/4V shift is unacceptable for a typical operation.

5. Gm/Mu/Rp DC measurements. Take these as estimates, rather than precise numbers - the tube gain/transconductance is too demanding to measure reliably on my gear.

6. Original datasheet

Legend: White curves: Ig<5uA Yellow: 5<Ig<20uA Red: 20<Ig<300uA. Measurements terminate at Ig>300uA

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