Last night I noticed I had little to no output from my KX3/KXPA100 combo especially on 40. I did a little experimenting and discovered that 3 turns of the transmit audio line through an unknown mix clamp on ferrite fixed the problem. Without it I was mildly affected on 20 and not at all on 15. With that choke in place I was stable on 40 and all other bands I tried. I am currently portable for work (in North Dakota) and am using a mobile antenna clamped to the top of a 6 ft tall wooden fence. Without the choke the ALC would go up when keyed, then drop off to near nothing. I know AFSK is becoming a more preferred method of generating RTTY, but I have never had this issue with FSK. So I learned a lesson about the little USB soundcard I use for portable ops.
On Mon, Aug 5, 2019 at 6:34 PM <[email protected]> wrote: > Hi Bill, > > > I've never experienced your reported amplifier drive problem with > my K3 s/n #6100 driving 20 watts into my Lunar Link LA-62 > 1500 watt output 6 meter amplifier. Perhaps it unique to the > K3 - KPA1500 combination. > > > 73 > Frank > W3LPL > > ----- Original Message ----- > > From: "Bill Schwantes" <[email protected]> > To: [email protected] > Sent: Monday, August 5, 2019 11:24:54 PM > Subject: [Elecraft] K3 Amplifier Drive Inconsistency > > 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] > > ______________________________________________________________ > 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] > ______________________________________________________________ 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]
