Cheap watts on 70MHz

A visit to an on-line auction site on 22nd October 2012 resulted in my purchasing, ( for about $18 ), an ex-commercial equipment radio frequency linear amplifier covering the band 60MHz - 80MHz, and probably capable of producing an output power of at least 100 watts. Very useful, I thought, for the amateur 70MHz VHF band.
I have no clue about the manufacturer. With the amplifier, however, came a much simplified hand-drawn circuit schematic with some notes in Russian.

To make it operational I mounted it inside a box, provided 24V, 12V and nominal 6V supplies, status LEDs, antenna changeover switching and a 7-pole Chebychev low-pass filter on the output.

 How smart it looks and it works too. What a bargain !