Don, It's good to see you're still carrying out your much appreciated good work here. I'd been away from this forum for a a couple years.
I changed R4 back to 100K. Dressing the ribbon and speaker cables doesn't help. Right now the KPA100 is outside the K2, on it's back, and cables are stretched tight and clear of the KSB2 board. I haven't done the KI6WX mod. For sure it's only 80 meters that has the problem. On other bands, it's almost indistinguishable whether the KPA100 is on or off, and audio is excellent. But on 80, both the cracking and general distortion start when I cross 10 to 11 Watts. CW is fine, although there is about a second of warble in the tone the first time I key after changing the band to 80). USB behaves the same as LSB. For a next diagnostic step, I'm thinking I could borrow my buddy's K2, try his KPA100 in my K2, and mine in his, and likewise for the KSB2 boards. Seem reasonable? Dick, K0KK Don Wilhelm-4 wrote: > > Dick, > > It puzzles me that it only appears on 80 meters. Do change R4 back to > 100k - the higher voltage is not required with the updated KPA100 (blue > toroids), and is undesirable. > > Do you have the KPA100 ribbon cable and speaker cable tucked up into the > corner of the KPA100 and dressed as far away from the KSB2 board as > possible? (remove the right side panel to check and tuck-in if necessary). > > Do you have the KI6WX increased gain mod on your KSB2. If so, have you > made the corresponding changes to the ALC section of the KSB2? > > 73, > Don W3FPR > > > radiotelegrapher wrote: >> I have moderate distortion of transmitted SSB audio from my KPA100, but >> ONLY >> on 80 meters. The distortion seems worsen and improve from time to time, >> with no apparent reason, and tapping components doesn't give a clue. >> Listening on a nearby receiver, and transmitting into a dummy load on 80 >> meters, the audio consistently sounds fine with the KPA100 off (at 10 W >> and >> less), but is distorted with KPA100 on (at 11W and higher). The >> distortion >> is particularly noticeable at the start of a new syllable, which sound >> like >> a loud crack. A constant amplitude, like a tuning fork by the >> microphone, >> sounds fine, so I suspect the TR switch or ALC. My build is Rev 3, Jan. >> 18, >> 2007. Searching the archives, I've found the usual causes, but the fixes >> are already included on my build: C31 is .22 mF, and R33 (1K) parallels >> RC3. I tried changing R4 from 100K to about 39K, but it didn't help. Any >> ideas? Dick, K0KK >> >> ------------------------------------------------------------------------ >> >> >> No virus found in this incoming message. >> Checked by AVG - www.avg.com >> Version: 8.5.423 / Virus Database: 270.14.45/2476 - Release Date: >> 11/02/09 07:51:00 >> >> > ______________________________________________________________ > 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 > > -- View this message in context: http://n2.nabble.com/K2-KPA100-transmitted-audio-distortion-80-meters-tp3929842p3935292.html Sent from the [K2] mailing list archive at Nabble.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
