Problem with Output Return Loss of 1.2Kw Amplifier

Hi everyone,

I have designed a 1.2Kw Power Amplifier and having trouble to get return loss not better than 0dB, now amplifier works between 2-30MHz and return losses are worse towards starting of the operating band.

I have got 1:3 transformer at output, primary is center taped DC with 100nF decoupling cap to ground. can some one tell me how can i improve the return losses, i have stabilized the transistor first before even starting the rest of the design K>1 every where in the band.
in fact K is much higher than 1 i.e. around 7 in the start of the band.

your help will be much appreciated,

thanks in advance

Power amplifiers are designed for efficiency. The concept of return loss is irrelevant for them.

but if out put return loss is positive at any point wouldn't it cause oscillation.

yes, it will oscillate if return loss is positive if you dB it.

You didn't mention, but I'm pretty sure you are talking about a simulation of 0dB return loss, and not about real measurement on a built power amplifier.

Old radio designers use to say when building high power tube amplifiers: "Tune for maximum smoke"

But don't follow this rule