I need help solving an amplifier drive inconsistency problem when I operate using digital modes on 50 MHz. I noticed during a recent contest that the K3 will sometimes key the amplifier but provide zero drive. I'm using K3 SN 669 on 50 MHz FT8, FT4 and MSK 144 and driving a KPA1500 to about 750 watts.
After several consecutive transmissions I notice that the amplifier responds briefly to being keyed but the power drops to zero. It's keyed up but has no output. The K3's output (drive) is set at 17 watts but there is no output on the RF meter when this happens. The K3's red TX indicator is on. This problem also occurs when driving a KPA500, though less often I can correct this problem temporarily by switching the amplifier to standby, which allows the K3 to change to "barefoot" output then switch the amplifier back to "operate" which changes drive power back to it's preset level. That's usually good for a dozen or so transmit cycles before the problem reappears. This problem does not occur when driving other amplifiers; nor does it occur when using CW or SSB modes. It seems to have something to do with the K3/KPA1500 command interface controlling the output power of the K3. Any ideas? 73 Bill W7QQ ______________________________________________________________ Elecraft mailing list Home: http://mailman.qth.net/mailman/listinfo/elecraft Help: http://mailman.qth.net/mmfaq.htm Post: mailto:[email protected] This list hosted by: http://www.qsl.net Please help support this email list: http://www.qsl.net/donate.html Message delivered to [email protected]
