Obviously something has changed. One element of your system can't handle the higher RF.
Note: use of the internal K3 tuner completely negates the accuracy of the external power/SWR meter since it is 'downstream' and not at the expected 50 ohms resistive. I'd start by replacing the patch cables, checking the choke (you DO use one, no?) for burns or other failure (replace?) and all connections at the antenna. I'm guessing you'll find something marginally 'off'. The analyzer won't catch it because it is very RF out. GL es 73, Rick wa6nhc Tiny iPhone 5 keypad, typos are inevitable On Feb 18, 2013, at 8:54 AM, "Terry Schieler" <[email protected]> wrote: > Yesterday, during the CW contest, I noticed that my K3-100 (#474) suddenly > began to "stutter" during CW transmissions on the low end of 40 meters. I > hadn't noticed this before, including Saturday, the first day of the contest. > My CW transmission had a "chattering" sound something like the braaaaap of a > machine gun (and no, my fist isn't *that* good). My first thought was RF > getting into the radio, but, I've never had RF issues before and, again, > nothing in the system had changed: > > K3 > LP-100A SWR/Power meter > 4 position Ameritron RCS-4 antenna switch > > dipole. > > I have never found a frequency on 40-10 meters that my K3's internal tuner > could not handle with the only antenna I've ever used with the rig. But the > tuner could not eliminate this chattering yesterday. > > After the contest I did some checking and noted the following: > > 1. At 100W, the chattering only occurred from 7.0 to almost exactly 7.1 then > went normal again. CW was normal on all other bands. > 2. If I backed the power down from 100W to 50W the chattering CW below 7.1 > went away and all was normal again. > 3. I checked my DX-EE parallel dipole and it was without damage or change. > 4. All coax connections in the feed line chain were tight. > 5. The meter on the K3 indicated a *tuned* SWR of 1.2 at 7.033 during the > chattering but the LP-100 meter showed 4.5 and up at the same time and its > alarm sounded. I'd never even heard the alarm before. > 6. I put my MFJ 269 analyzer on the PL259 that connects the 10-40 meter > dipole to the K3 and swept the bands. No band had an SWR greater than 2.4, > which the K3's tuner should (and always has) handle well. > > All in all, the rig performed extremely well in the contest except for this > new chattering issue. I logged many stations that I could barely hear. Now > all I can think is that the K3's internal tuner somehow is losing its memory. > So I went back to each band and did a few "manual" antenna tunes. SWR on > the lower end of 40 meters tuned to 1.2 in several places but the chattering > CW continues there with power above 50 watts. Are there any tests I could > perform to determine if the memory function of the K3's internal tuner is > intermittent or otherwise suffering. Thanks. > > 73, > > Terry, W0FM > ______________________________________________________________ > 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 ______________________________________________________________ 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
