GU-81M power amplifier with GU-72 driver
Top-10
Amplifier built on a GU-81M tube.
Input driver built on a GU-72 tube.
Input power from 20 to 30 Watt
Output power up to 1200 Watts
Frequency band from 1.8 MHz up to 28 MHz
A two-stage HF linear: a GU-72 driver takes 20–30 W from the rig and drives a GU-81M final, which puts out up to 1200 W.
Specifications
- Final tube: GU-81M
- Driver tube: GU-72
- Bands: 1.8–28 MHz
- Drive: 20–30 W
- Output: up to 1200 W
About the GU-81M
The GU-81M is a generator pentode in a glass envelope with natural cooling, made for RF amplification up to about 50 MHz. The anode is rated for 450 W dissipation.
With the driver stage in front of it, the final gets enough drive while the transceiver loafs along at a fraction of its usual 100 W. Set the rig's power to 20–30 W before keying into the amp. Extra drive only spoils the signal.
On the air
The range covers 160 through 10 m. On 160 and 80 m the extra power helps at night for DX and in contests; the higher bands need decent propagation to open for long-haul contacts.