GU-74B tube power amplifier
Top-10
Amplifier builded on top of GU-74B tube, which is used in wideband nontunable amplifiers and for single-sideband power
amplification in stationary and mobile RF equipment. It is useful at full ratings through 250MHz.
The GU-74b tube is generally considered to be similar to the 4CX800A,
although some users report that it acts more like a tube having 900 or 1000W anode dissipation.
For more information see
Input power from 25 to 30 Watt, and output power up to 650 Watt.
A single GU-74B linear amplifier that turns 25–30 W of drive into up to 650 W on the output.
Specifications
- Tube: GU-74B, one
- Drive: 25–30 W
- Output: up to 650 W
- Gain: about 13–14 dB (from the figures above)
About the GU-74B
The GU-74B is a metal-ceramic tetrode with forced-air cooling. Its rated anode dissipation is 600 W. Being a tetrode, it needs its own screen-grid supply on top of the anode supply.
Most HF rigs put out around 100 W, so the transceiver has to be turned down to the 25–30 W this amp wants. Check that the rig holds that level on voice peaks. Overdrive gives a wide, dirty signal and works the tube harder than needed.
On the air
650 W is the top figure. For RTTY, FT8 and other modes with a steady carrier, many operators run a tube amp a bit below its SSB peak level to keep the anode cooler.