Thanks, Jim and all the elecrafters responded to my question about using KPA500 under full power in RTTY contest. Some of the answers came to me under private emails off the list. I would like to thank them as well. From all the responses, KPA500 is a solid performer under full power in all modes including those high duty cycle. I mostly operate SSB so that I do not have much chances to operate KPA500 under high duty cycle. Hence, I put up my question in this email listing. 73 Johnny VR2XMC 寄件人︰ Jim Brown <j...@audiosystemsgroup.com> 收件人︰ elecraft@mailman.qth.net 傳送日期︰ 2015年04月26日 (週日) 5:02 AM 主題︰ Re: [Elecraft] KPA500 - Full Power Keydown On Sat,4/25/2015 11:21 AM, Kevin Stover wrote: > All of this anecdotal eveidence is interesting but meaningless.
Is it? The original post asked who had actually used the KPA500 that way. He got several responses, including mine. > Elecratf advertise and rate the amp as a 500W amp. Not 600, not 700. I stated my experience. The difference between 500W and 600W is 0.8 dB. The difference between 500W and 650W is 1.1 dB. Early versions of K3 firmware allowed it to cranked to 120 W. That was reduced to 110 W to place an upper limit on IMD. > Someone should put the amp on an spectrum analyser while running at 700 wats > to see whatr it looks like while being overdriven. You can bet that Elecraft did that throughout the design process, and probably in final test of the power modules. I know the guy who did that testing. :) I've done it myself. It remains clean at the highest power I can get out of it, which varies a bit depending on the load Z between 600W and 700W. I've published a link to those measurements several times on this reflector. k9yc.com/P3_Spectrum_Measurements.pdf and k9yc.com/FTDX5000_Report.pdf The highest power in these reports is 550W, but I've measured up to 650W and the sidebands get slightly wider (5-10%) and a few dB stronger. > Elecraft have also said, in the operating manual, that the time limnit is 10 > minutes key down. Did they put that line in the manual just to take up space > or is it purely CYA? That's a reasonable spec based on my observations with a thousand or more hours of use. > > Jusdt because some people are overdriving the amp and getting away with it > doesn't mean it was designed for it. It's pretty difficult to overdrive the KPA500 -- if you supply more drive than it wants, it will insert an attenuator between the input connector and the power amp stage to keep the power within design parameters. Protection circuitry in the K3, KX3, KPA500, and KAT500 is set to prevent destructive overheating and keep the signal clean. On Sat,4/25/2015 12:04 PM, Harry Yingst via Elecraft wrote: > I'm looking for people who actually run it at 500 watts in SSTV, or other > like modes (not voice) A SSTV picture can take 110 seconds If it will do 500W keydown for 10 minutes, it will do 110 seconds for SSTV. :) 73, Jim K9YC ______________________________________________________________ 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 Message delivered to vr2...@yahoo.com.hk ______________________________________________________________ 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 Message delivered to arch...@mail-archive.com
