Since the K3 (like virtually all current rigs) has fixed-tuned output filters, the match to the finals (and so the efficiency) will degrade as you go beyond the output power (and so impedance) for which they were designed. That means more current demand, more heating and perhaps new final transistors at regular intervals, Hi!
Linearity will suffer which causes hard keying - perhaps even "clicks" - on CW and higher IMD in any mode using SSB: voice, data, etc. Of course, you can redesign the output filters as needed, but the basic limitation of linearity at higher power from a low-voltage (13VDC) transistor is a tough one. Low voltage results in a very low and difficult-to-handle output impedance from the finals at higher output powers. It's the reason 13VDC rigs typically don't exceed at 100 watts. Higher power rigs normally use a higher voltage on the transistors - frequently 50 VDC - and so have a higher output impedance. Of course that adds the weight and complexity of an internal DC-DC converter to supply the higher voltage to the finals. Bottom line, I'd expect 150 watts is 'do-able' but at considerable expense and redesign effort to produce a clean signal, all for an improvement that *may* be just discernable on a very good S-meter in one QSO out of a thousand. Ron AC7AC ______________________________________________________________ Elecraft mailing list Home: http://mailman.qth.net/mailman/listinfo/elecraft Help: http://mailman.qth.net/mmfaq.htm Post: mailto:Elecraft@mailman.qth.net This list hosted by: http://www.qsl.net Please help support this email list: http://www.qsl.net/donate.html
