Geoff has touched on what may be happening. I've seen this on my systems here too... and the issue comes down to the material, in this case mud or water and dust... collecting on the feeder, then as the moisture drys away, the change in transmission line characteristics also change. There are a whole page of math equations and figures that prove this, but suffice it to say for now, that open wire, doesn't have this issue... it has others... more physical, like how to keep it spaced and installed correctly.
Retuning isn't a real problem, it is pretty much just adjusting for what the moisture is changing. However... be watchful for the moisture changes to not go away completely.... then go look for where the moisture isn't leaving and find an opening in the insulation, and repair it, before the feedline becomes damaged too much by the moisture invasion. Still beats coax for losses. --... ...-- Dale - WC7S in Wy > From: gm4...@btinternet.com > To: k...@mac.com > Date: Thu, 22 Oct 2009 11:53:53 +0100 > CC: elecraft@mailman.qth.net > Subject: Re: [Elecraft] K3 KAT3 Antenna Tuner Tutorial > > Windy, > > What sort of arrangement are you using to connect the feeder to the antenna? > > Do you get a lot of wind-blown dust / sand during the dry weather, some of > which might be staying on the feeder until most is washed off by rain. > > 73, > Geoff > GM4ESD > > > Windy KM5Q wrote on Thursday, October 22, 2009 at 4:38 AM > > > Here's another question: I have a dipole with 200 feet of window-line > > feed. It works great with the ATU. When it's wet, I have to re-tune, > > then it's fine again. > > > > I've tuned it at lots of spots in some favorite bands during dry > > weather (most of the time in New Mexico). But on a rainy day, I end up > > retuning frequencies here and there. Next sunny day, does the system > > detune me when I run into a previously "wet-tuned" segment? > > > > Oddly, I haven't observed this, but I don't understand why. > > > > Windy KM5Q > > > ______________________________________________________________ > 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 _________________________________________________________________ Windows 7: I wanted more reliable, now it's more reliable. Wow! http://microsoft.com/windows/windows-7/default-ga.aspx?h=myidea?ocid=PID24727::T:WLMTAGL:ON:WL:en-US:WWL_WIN_myidea:102009 ______________________________________________________________ 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
