Tom:
Our problem with those Russian tubes is, that very little if ever seems to
have been published of how linear they are in SSB? Nothing about distorsion
like in the EIMAC publications. Those surplus tubes from the miltary must be
of high quality and reliability as much money and effort was put into this
according to Russian hams on the bands.
One important question is, why they did not they make copies of the
excellent 88 family (8877, 8874 etc) and why did not the proposed 3-600Z
come out from Svetlana?
Lets here your answer on that Tom?
----------
>Från: w4th@webtv.net (Tom Hix W4TH)
>Till: amps@contesting.com
>Kopia: rexjo@bellsouth.net
>Ämne: [AMPS] possible amp tube
>Datum: lör 18 nov 2000 07.12
>
>
>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.
>==================================
>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/
>
>
>--
>FAQ on WWW: http://www.contesting.com/FAQ/amps
>Submissions: amps@contesting.com
>Administrative requests: amps-REQUEST@contesting.com
>Problems: owner-amps@contesting.com
>
>
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