Seeing a 1.1:1.0 SWR at the amplifier doesn't necessarily mean your antenna is working as you expect. Without getting into details, I am sure others will chime in, your antenna setup is highly suspicious given what you have briefly reported. You didn't indicate antenna type, feedline, feedline distance, etc. You might find reading an antenna handbook very informative. You can also YouTube or do on line searches to learn about antenna matching. As a KPA1500 owner, my antenna setup doesn't give me anything close to what you are experiencing. Are you using the built in tuner? Have you used an antenna analyzer to determine the antenna's characteristics on the frequencies you included in your questioning?
73, Bill K9YEQ https://wrj-tech.com/ -----Original Message----- From: elecraft-boun...@mailman.qth.net <elecraft-boun...@mailman.qth.net> On Behalf Of Jim McCook Sent: Saturday, August 24, 2019 1:45 PM To: Elecraft Reflector <elecraft@mailman.qth.net> Subject: [Elecraft] KPA-1500 Power Output Variation I'm using my K-3 with the KPA-1500 and have a problem with extreme changes in power output with a given drive level on 40m CW. This happens to a lesser extent on other bands with different antennas. My 40m antenna is tuned to 7.025 where SWR is 1.1:1. On 7.000 it is 1.4:1 and at 7.050 it's 1.3:1. Within that range of frequencies the output _without_ the tuner at a given drive level (30w) varies from 1300w to well over 1700w. Using careful _tuner_ settings it's only slightly better. I have to reduce drive to 24 or 25w to get below 1500w, depending on the temperature of the amplifier (power output varies a lot with temperature changes). Higher temp = lower output. I have tried to compensate in the segments where output is excessive by using manual settings via the Utility. This has helped slightly, but still isn't adequate. I've resisted using ALC because of concern for generating distortion. Having to ride the drive level from the K-3 is a PIA, especially during contests. It seems to me a good answer would be to have higher input attenuation so drive requirement would be higher, maybe around 70+ watts. I'd expect changing drive level by the same number of watts (5 or 6) would not affect output as much. I'd also assume the power output would not vary nearly so much with a given drive level. Is this a possible solution? I've also understood that most transmitters (even the K-3) have cleaner output near highest rated output. Help! Jim W6YA ______________________________________________________________ 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 k9...@live.com ______________________________________________________________ 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
