GK-71 HF Amplifier with GU-29 Driver
Top-10
A GK-71 in the output stage with a GU-29 driver in front of it. It needs only 18–20 W of drive and puts out 750–800 W.
Specifications
- Output stage: GK-71 (ГК-71)
- Driver: GU-29 (ГУ-29)
- Bands: 3.5–28 MHz
- Drive: 18–20 W
- Output: 750–800 W
- Input SWR: 1.0–1.5
- GK-71 anode voltage: 2800 V
- Anode supply: a separate box on a cable
- Gain: about 40 times, roughly 16 dB
Circuit and build
An input SWR of 1.0–1.5 is close to a perfect load for the transceiver, and its SWR protection normally stays quiet. A 100 W rig has to be turned well down.
2800 V on the anode can kill, and the filter capacitors hold their charge after switch-off. Discharge them before reaching inside.
About the tubes
The GK-71 is a glass transmitting pentode with an anode rated for 125 W of dissipation. The GU-29 is a dual beam tetrode, the Western equivalent is the 829B.