Transformerless 5× GU-50 HF Amplifier
Top-10
Five GU-50 tubes and no power transformer. The amplifier is built as a transformerless design and gives 500 W from 50 W of drive.
Specifications
- Tubes: 5 × GU-50 (ГУ-50)
- Bands: 3.5–28 MHz
- Drive: 50 W
- Output: 500 W
- Power supply: transformerless
- Gain: 10 times, 10 dB
Circuit and build
Transformerless builds usually take the anode voltage straight from the mains through a rectifier, often with a voltage multiplier. That saves a lot of weight, but every circuit is tied to the mains. Good insulation and care during alignment are a must: the inside of the case is dangerous even with no RF present.
Each tube gives about 100 W of output on average. The GU-50 itself is rated for no more than 40 W of anode dissipation.
On the air
For 50 W of drive a 100 W transceiver only needs to be cut in half.