You are probably matching the losses in the feed line, when you try to load a 40 meter dipole on 20. Check the coax loss versus VSWR for 20 meters at a VSWR of 89. Please do not do this at high power George, W6GF
________________________________ From: Brian Alsop <als...@nc.rr.com> To: Elecraft@mailman.qth.net Sent: Saturday, December 8, 2012 12:12 PM Subject: Re: [Elecraft] KAT500 Tuning issue Jerry, If you want some numbers to chew on. @65' a 40 meter dipole has an impedance of about 73 ohms. SWR=1.5 The same antenna on 20M has an impedance of 3788 - j1648 ohms with an SWR of 89! Very high impedance. Why the K3 matched it, I can't say. Do you think the KAT500 should be able to handle this? Their specs are for way less than this. 73 de Brian/K3KO On 12/8/2012 19:57, Jerry Weisskohl wrote: > 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:Elecraft@mailman.qth.net > > This list hosted by: http://www.qsl.net/ > Please help support this email list: http://www.qsl.net/donate.html > > > ----- > No virus found in this message. > Checked by AVG - www.avg.com > Version: 2012.0.2221 / Virus Database: 2634/5446 - Release Date: 12/08/12 > > ----- No virus found in this message. Checked by AVG - www.avg.com Version: 2012.0.2221 / Virus Database: 2634/5446 - Release Date: 12/08/12 ______________________________________________________________ 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 ______________________________________________________________ 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
