GS-35B Specifications, Dimensions and Data

GS-35B Triode Specifications

The GS-35B is a medium mu triode that yields about 13 db gain in amateur service. These same specifications can be applied to the GS-7B which appears to be a commercially produced version of the GS-35B. Although the GS-31B has the same base as this tube, it has a much smaller anode cooler and is rated for much less power.

Amateur amplifiers have been built using this tube for every band from 160 meters through 23 cm.

Tube Dimensions (mm)
(click on the picture to get a larger printable image in a new window)

OK, Translate this for me please...

The anode (A) diameter of 100.2 mm is close enough to 4 inches for government work. It is 3-3/32 inches high.
The grid ring (C) is used for mounting the tube. It has a flanged ring that's 60.3 mm in diameter which fits a 2-3/8 inch hole. The 65 mm diameter flange will rest on the edge of that hole as long as you clamp it well. The flange measures about 0.29 inches thick. This mounting is critical for removing heat from the grid and the lower part of the tube as well as the critical grid to ground electrical connection.
The connection for the filament and cathode (kn on the diagram) is 1-3/4 inches in diameter.
The other filament connection (n) is 1-1/16 inches in diameter.
The GS-35B is heavy at just over 6 lbs including the copper heatsink.
One thing needs clarifying: The spec sheet says the life to be expected from a GS-35B is 500 hours. This is a very conservative rating provided by the Union plant for the Russian military. There are a number of these tubes in service with a few thousands of hours operating time with no indication of a decrease in emission or filament failure.

Physical Characteristics
Envelope	metal-ceramic
Cooling	forced air
Minimum required Air flow	1500 l/min (90 cfm)
Diameter	100.2 mm max
Length	min 173 max 177mm
Anode Diameter	min 99.7 max 100.2 mm
Grid diameter	min 59.5 max 60.3 mm
Cathode	indirectly heated, oxide coated
Cathode Diameter	min 40 max 40.5 mm
Heater Diameter	min 25.6 max 26.2 mm
Weight including copper heatsink	2.8Kg (6.17 lbs)

Electrical Parameters
Heater voltage (Volts) 11.9-13.3 VAC / Typical 12.6 V	12.6
Heater current (Amps) (Typical 12.6 V / 2.95 (+/- 0.3) A)	2.65-3.25
Mutual conductance (at anode = 2.5 kV, grid voltage change -1 V, anode current 0.4 A), mA/V	25-40
Penetration factor (at anode voltage 2.5 kV, grid voltage change -200 V, anode current 0.4 A), %	0.8-1.2
Operating point (negative grid voltage at anode voltage 2.5 kV, anode current 0.4 A), V	12-6
Warm up time (seconds) at least	>90
Interelectrode capacitance (pF):
Input C, (c-g)	18-24
Output C, (g-a)	3.8-5.0
Transfer C, (c-a)	<0.12
Output power (Watts):
at anode voltage 2.5 kV, anode current 0.7 A, wavelength 60 cm, at least	800
at anode voltage 2.2 kV, anode current 0.8 A, wavelength 30 cm, at least	350
Output power over 500 h of service (at anode voltage 2.5 kV, anode current 0.7 A, wavelength 60 cm), W, at least	650

Operational Limits
Frequency	1000 MHz
Heater voltage	11.9-13.3
Anode voltage, kV:
DC	3
Instantaneous value	6 (pulse)
Grid voltage	-400 to +120
Cathode current (Amps)	1.4
Dissipation (Watts):
Anode	1500
Grid	26
Temperature (°C):
Anode	200
Grid and cathode leads	120

Environmental Limits
Vibration frequency range, Hz	50-200
Acceleration, m/s²	59
Multiple impacts with acceleration, m/s²	343
Linear loads with acceleration, m/s²	88
Lowest ambient temperature, °C	-60
Relative humidity at up to +40 °C, %	98

Averaged Anode and Grid-Anode Characteristic Curves:
U_f = 12.6V
_____ anode;
_ _ _ grid-anode

Characteristic Curves Showing Output Power versus Anode Current:
U_f = 12.6V; L = 30cm

Characteristic Curves Showing Output Power versus Anode Current:
U_f = 12.6V; L = 60cm

Click here for Data Sheet in PDF format (176k)

These are the dimensions for the tube base and hole cutout that I used
They have been converted to inches
(click on the picture to get a larger printable image in a new window)

GS-35B Base - click to see a larger picture in another window