If the feed line happens to be near an even multiple of a half wavelength the impedance will be very high and there will be a voltage loop (HV point) at the tuner. As someone else noted, losses would also be very high, so using a 40m coax fed dipole on 20 is a poor idea.
Vic k2vco On Dec 8, 2012, at 12:37 PM, "hawley, charles j jr" <[email protected]> wrote: > Now that I think about it, if you have a different feedline length depending > on tuning from the output of the KAT or tuning from the output of the K3 with > both in line, that may make enough difference in the required values to tune. > > Chuck, KE9UW > Lionel Trains, TCA, LCCA, LRRC > aka Jack, BMW Motorcycles BMWMOA #224 > > ________________________________________ > From: [email protected] [[email protected]] on > behalf of hawley, charles j jr [[email protected]] > Sent: Saturday, December 08, 2012 2:33 PM > To: Jerry Weisskohl; [email protected] > Subject: Re: [Elecraft] KAT500 Tuning issue > > One thing I ran into with an automatic "hi powered" tuner is that the > firmware does not allow all the otherwise available values of the components > on certain bands. This is done in the case of the MFJ tuner I am using (now > until the KAT arrives) on 40 Meters so that the voltage and current limits > are not exceeded when handling full rated power. I don't know if the KAT500 > has this implemented or if in the case of the higher power capability, it > just doesn't have quite the range of the 100 watt tuner in the K3. > As was mentioned in a similar thread, you might experiment by changing your > feedline a few feet plus or minus to find a more satisfactory matching > situation on some bands. > > Chuck, KE9UW > Lionel Trains, TCA, LCCA, LRRC > aka Jack, BMW Motorcycles BMWMOA #224 > > ________________________________________ > From: [email protected] [[email protected]] on > behalf of Jerry Weisskohl [[email protected]] > Sent: Saturday, December 08, 2012 1:57 PM > To: [email protected] > Subject: [Elecraft] KAT500 Tuning issue > > I believe I have run into a problem with the KAT500 tuner and wanted to > mention it to see if anyone else is experiencing the same issue. I just > received the KAT500 tuner and the KPA500 amp and got it up and running > with my K3. The KPA500 works great but I am finding that the KAT500 is > unable to tune my 40 meter wire dipole on 20 meters. The best it can do is > 3.75 - 1 swr which trips the FAULT light on the KAT500. The internal tuner > in the K3 has been able to tune this antenna on all bands without issue. > Also the KAT500 is unable to tune 28400 below 2.5 - 1 while the internal > tuner in the K3 has no problems tuning that frequency. I have two antennas, > my other one is a 80 meter vertical so I switch to that for 20 meters but I > don't understand why the KAT500 is unable to tune certain frequencies when > the internal tuner on the K3 is able to do so. > > I called Elecraft and spoke to David who had me take the KPA500 out of the > picture by connecting the KAT500 directly to the K3. I had the same > results. David then sent me the latest unofficial KAT500 firmware 1.18 > which I installed. It did not make any difference. > David had me try tuning using the utility, again no difference and still > unable to tune 20 meters below 2.75 - 1 on my 40 meter wire dipole. > > In general I am finding that the internal tuner does a much better job > tuning my antennas then the KAT500. I wonder if anyone else is experiencing > the same problem. > > As far as the settings on the K3 I am using the following: > COnfig:PWR Set = Per Band > COnfig:Tune PWR = 15 > > I guess I will hope that this can be addressed through a later firmware > release. Meanwhile, the KAT500 is the weak link in my system. The KPA500 is > fantastic, just need to resolve this tuner issue. > > Jerry - AC4BT > ______________________________________________________________ > 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 > ______________________________________________________________ > 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
