It's an orphan. I'm told it's a "Gray" amplifier. Might be. Never was a diagram that escaped into the wild for that one that I know.
Never needed one, really. It's pretty simple. Biggest drawback was the power supply. Unregulated, would put over 20 Volts on the RF transistors in standby. Dropped to more like 12 or 13 Volts under load while keyed up. That 20 Volts would tend to assassinate RF transistors if you got them a little hot. Used a stopgap that placed a 30-Amp automotive relay between the power supply and amp board, wired to the keying relay. Only put DC power to the transistors when they have RF drive, draw current and pull the supply voltage down to the safe range. The power transformer is so undersize that it eventually overheats and fails.
There is no fixed bias source for the RF transistors, so sideband will sound like doo-doo.
If the resistors on the high/medium/low switch are burned up, either they were too small, or someone used a radio that was too big.
Or both. Seems to me we used an example from the schemo of another amplifier to replace resistors burned beyond recognition.
Here's one. Has three levels. http://73.235.100.209/Amp/palomar_other/elite/pal_hd400.gif
Learned to put a SWR meter and coax jumper between the radio and amplifier to make sure the amplifier's input SWR doesn't get out of hand.
A carrier power of 30 to 50 Watts is more realistic for a small 2-transistor amplifier. Probably won't sound so good at a 90-Watt carrier.
73
