This compact linear amplifier runs a quad of 811-A vacuum tubes in grounded grid, and delivers 600 watts PEP SSB power output
with 48 watts of drive power. It has a band switched plate tank allowing operation of the bands 160 through 20 meters.
The entire unit including its HV Plate Supply is shoehorned into a cabinet measuring 7 x 14 x 12 inches (HWD). I built this
amplifier back in 1991, and at that time Asian mfg. 811-A could be had for $10 each brand new. It still has the origina Jolada
tubes, made in China. RF output power is down a bit after decades of SSB ragchew weekend QSOs' on 160 and 80 meters.
Not visible in this interior photo is a fan just below the 4 vacuum tubes. The fan pulls in cool air from under the cabinet and moves the air straight up to the tubes, and out through ventilation holes in the top of the cabinet.
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