These amps are not that good,i had one that looked brand new and i sold it for 300 bucks(got it from a ham)Those baby tubes 250b get hurt too easy by overdriving.Id rather have 6lq6s in my amp
You admittedly abused the amp, and then blame the amp? On top of this, you would rather use a TV sweep tube than an actual broadcast tube designed for amplifier service? Really?! Can you be educated? I'm going to try......
The Pride DX-300 is a great small amplifier. Some fools think they can beat the hell out of a 250 watt tube and have it put out a kilowatt. How long do you expect this small tube to survive when you abuse it?
The 4CX250B is a TETRODE tube meaning it has 4
active elements (hence the "4" in the part number)
cathode (with heather/filament)
is what separates the TETRODE from the TRIODE. I'll save all the advantages and disadvantages of the tetrode over the triode except to say that the tetrode is more efficient and takes less drive power
to get the same output power of the triode. A triode can take more abuse however.
I used to say that 2 tubes is all you need. I now subscribe to the single tube rule, which is, "If a single tube doesn't give you the desired output power, buy a BIGGER tube."
The PRide DX-300 was designed in the 70s to be driven by the radios of the time, that were operating at 5 watts. You can run higher power radios by swampping the input of the amp (like the Pride KW-1, designed for 100 watt radios and no where as clean as the DX-300!).
Run it right, and the DX-300 is an excellent amp! Run it like an idiot and you WILL destroy it. But please......don't blame the amp when its clear where the real problem lies.