I am going to get bushwhacked on this one but here goes:
I came to the hobby via cb. I have an old Zetagi 550p (4x mrf455) gives around 300w ssb with a 20w drive. Ok, it doesn't have filters. But if you replace the 6 level attenuator board with a decent 6 band pass filter-board (I can construct one) it should pass muster. The snag is it is supposed to be only usable on 20mhz and up. I want to use it on 20m n 40m if possible. Any ideas to make it a decent 300w amp on these freqs? I can provide the circuit which is available on the 'net.