Re: Ebay SSPA 40W Power Amplifier module for 13cm - Doherty Amplifier

Chris Bartram G4DGU

Hello Paul

Those amplifiers will be designed to give a combination of good linearity and efficiency at the 40W level, and the input/output matching will reflect that.  It may be that the modulation scheme for which they were designed had a fairly large peak to mean ratio, in which case the amplifier will probably give significantly more peak output power, but then you may run into problems with dissipation. The dissipation/current carrying ratings of the associated networks and cooling arrangements may also be challenged. Having said all that, the only way to find-out without more information than is probably available is to try - if you are prepared to take the risk! I suspect you may get a couple of dB more out, but you are likely to reduce the lifetime of the amplifier significantly.

The Doherty amplifier is usually used as a means of improving efficiency, and thus reducing the electricity bill of the user. I looked carefully at the potential of this technique for use in amateur amplifiers a few years ago, but came to the conclusion that it didn't offer a significant improvement in performance in amateur service.


Chris G4DGU

On 13/10/2020 14:52, Paul Randall G3NJV wrote:
Quick question, these modules contain two devices each capable of 130W CW, yet the amplifier only gives 40W.
Is there a "simple" modification that can be performed to improve this?
I imagine I'm not the first person to consider this.

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