Will the guys that are into building amateur pa amps please take a look
at the specs for this big Russian tube, and see what you think the
prospects would be for building an amp with this tube. This thing is
about a foot high, and about the size in diameter of a pound coffee can.
Here is a pix.
http://www.tubes.lt/gif/gu-81m.gif
And here are the specs.
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The GU-81M pentode is used in self-excited oscillation and power
amplification circuits of RF equipment.
GENERAL
Cathode: directly heated, carbonized thoriated tungsten.
Envelope: glass, with base.
Height: at most 260 mm.
Diameter: at most 202 mm.
Mass: at most 1 kg.
OPERATING ENVIRONMENTAL CONDITIONS
Ambient temperature, °C -10 to+ 55
Relative humidity at up to +25 °C, % 98
BASIC DATA Electrical Parameters
Filament voltage, V 12.6
Filament current, A, at most 11
Mutual conductance (at anode voltage 2 kV, grid 2
voltage 600 V, anode current 200 mA), mA/ V 4.5-6.5
Gain coefficient (grid 1 -grid 2) (at anode voltage 2 kV,
grid 2 voltages 600 and 500 V, anode current 200 mA) 2.5-4
Bias voltage (at anode voltage 2 kV, grid 2
voltage 600 V), V 116-160
Interelectrode capacitance, pF:
input 25-32
output 21-26
grid 1-anode, at most 0.1
grid 1-grid3 1-4
Output power (at anode voltage 2 kV, grid 2
voltage 600 V, bias voltage -200 V, grid 1 drive voltage
amplitude 300 V, anode current, at least 450 mA,
grid 1 current at most 20 mA, grid 2 current,
at most 220 mA), W, at least 700
Limit Operating Values
Filament voltage, V 11.6-13.4
Anode voltage, V:
at frequencies not above 6 MHz 3
at frequencies not above 24 MHz 2.5
at frequencies not above 50 MHz 1.5
Grid 2 voltage, V 600
Anode current (average value), A 0.6
Grid 1 current (average value), A 0.02
Grid 2 current (average value), A 0.2
Dissipation, W:
anode 450
anode (momentary dissipation) 600
grid 2 120
grid 1 10
Envelope temperature, °C 350
PENTODE GU-81M
CONNECTION
OF ELECTRODES
WITH LEADS
1, 2 -cathode; 3 -grid 1;
4 -grid 2; 5 -cathode centre tap;
6, C3 -grid 3; A -anode
===================================
Be sure to visit my web sites.
Tom's Tubes, Svetlana Amateur Radio Amp Tubes.
http://msnhomepages.talkcity.com/ClassifiedsCt/tomstubes/index.html
Ham Radio Homepage.
http://www.geocities.com/bamagramps/
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