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Linear Power Amplifier on G811

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ANTENTOP- 01- 2010, # 012

Linear Power Amplifier on G811




S. Bunin, L. Yailenko


Credit Line: Spravochnic Radiolyubitelya Korotkovolnovika, - 2 Izdanie, Kiev : Tehnika, 1984.

(“Reference for Ham”)



The PA is designed for ham bands 160- 10- meters. It provides 200 Wtts CW/ 500 Wtts PEP SSB. Efficiency of the PA is 65- 70% in depend on used r\band. Figure 1 shows the schematic of the PA.


Four tubes G811 (switched in bridge, grounded grid) are used in the PA. Four tubes may dissipative 160- Watts on their plates, so, the PA can work continuously with 200- Wtts output. Input resistance of the PA is closed to 75- Ohm at 160- 10- meters.

RX: Tubes are closed by minus 27-V that is coming by relay K1. Contacts of the relay switch antenna to X3- Receiver Input.


TX: Grids of the tubes are connected to the ground by pedal S1, antenna through contacts of Relay K1 goes to PA output.

Transformer T1 provides 2x6.5-V at 8- A. It should stand 110- Wtts.

Inductors L1, L2, L3, L4 are wound on Russian Resistors MLT- 2 (for sizes see: Each inductor contains 5 turns and coiled by wire in dia 0.62- mm (22- AWG).


Plate choke L6 is wound on porcelain form in dia 20- 25-mm and 150-mm length. It contains 150 turns, 50 turns at plate side is wound with gap 0.5- mm. Was used wire in dia 0.35- mm (27- AWG) in silk insulation.


Chokes L7 and L8 is commercial made from old military equipment. May be used any suitable chokes.




Figure 1 Schematic of the Four- G811 PA

Page 87


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Last Updated:

January 22, 2020 22:38

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