>From my understanding of it the radio has the KPA3 switched out of the loop until you cross the 12W mark. Then it starts actually putting it into the signal path. Until you crank the power up beyond 12Watts the KPA3 is nothing more than an added current drain. But if you turn things up to 12 or 13 watts you're probably still quite fine with those levels for RFIing yourself and the rest of the house / neighborhood and your KPA3 will have TONS of headroom for you in that configuration. Yet as far as the low power amp its still probably still rated at the same 100% duty cycle at full power for 10 minutes. I say probably because the only technical spec listed is that it will handle 100 watts for 10 minutes easily on the web site and in the manual. I'd imagine that similar margins are used on both PA's being that both are designed to have a 20% overhead which is more than you get from Yaecomwood out of the gate!
One big advantage is that getting the KPA3 now is a smart investment as it is probably only going to go up in price and you have a great advantage with the current exchange rate as it is. Not to mention that if you were ever to want to sell your K3 the fact that a KPA3 is already installed makes it much more attractive to many more people. My motto has always been its better to have than to want. ;) On Mon, 2008-03-17 at 02:55 -0700, G4ILO wrote: > I run QRP out of practical necessity. I'm forced to use attic antennas and I > don't wish to induce more RF into the domestic electrical equipment (or me, > for that matter) than I absolutely have to. > > Nevertheless, I'm thinking about getting a KPA3, because it probably will > never be cheaper than it is now, and the occasion might arise in future when > I might be able to use it. > > I'm just wondering if there are any advantages to using the PA when running > QRP. As I understand it, the PA is switched out of circuit until you dial > the power above 10W, just as in the K2. There is no option for class A > operation at a lower power level to produce a cleaner signal. If I run 10W > of FM, the QRP PA will do all the work, and warm up very quickly, instead of > letting the KPA3 do most of the work and barely getting warm. If I run 5W of > PSK31, the IMD generated by the low power PA running at half its rated power > will be higher than the KPA3 loafing along at the same power level. > > Unless I'm missing something, there would be no benefit to me at the moment > from having the KPA3 unless I want to wind the power control above 10W. Am I > right? > > ----- > Julian, G4ILO K3 s/n: 222 K2 s/n: 392 > G4ILO's Shack: www.g4ilo.com > Zerobeat Ham Forums: www.zerobeat.net/smf _______________________________________________ Elecraft mailing list Post to: Elecraft@mailman.qth.net You must be a subscriber to post to the list. Subscriber Info (Addr. Change, sub, unsub etc.): http://mailman.qth.net/mailman/listinfo/elecraft Help: http://mailman.qth.net/subscribers.htm Elecraft web page: http://www.elecraft.com
