The fact that the tuner may run longer to find a match on some frequencies means nothing. If it finds a match, the match is as good as if it found it instantly and there are no higher losses in the tuner and antenna system associated with the longer search times.
Also remember when trying the KAT500 with a new antenna, pressing TUNE again immediately after the search stops will cause it to repeat using finer steps of L and C which can often improve the match. That also means nothing in terms of the efficiency of the system. It simply indicates that, possibly, the antenna "Q" is high enough that the point of low SWR is rather narrow. In that case you can expect the KAT500 to retune more frequently when operated in AUTO mode as you QSY around the band. When the antenna is electrically short (e.g. less than 1/4 wavelength) on the operating frequency, a high "Q" requiring frequent retuning indicates the antenna system is quite efficient. Low "Q" - wide SWR bandwidth - in an electrically short antenna is a solid indication there are losses in the system. 73, Ron AC7AC -----Original Message----- From: elecraft-boun...@mailman.qth.net [mailto:elecraft-boun...@mailman.qth.net] On Behalf Of David Bunte Sent: Saturday, July 27, 2013 10:58 AM To: Javier Campos Cc: elecraft@mailman.qth.net Subject: Re: [Elecraft] KAT-500 and 30' Flag Pole Antenna Users? Javier - I have some thoughts on this matter, but not a LOT of answers. I see that you got a response from someone telling you about their vertical (not like yours), and the MFJ tuner (not the KAT500). What he said about putting the tuner at the antenna makes a lot of sense, but I tried the MFJ at the base of my 30' Zero Five, and it could not find a good match on all bands. It did better, further away from the antenna, and I am sure that is because the loss in the coax between the tuner and the antenna, changed the system parameters enough that the tuner had a better chance of handling the mismatch. I actually tried a KAT500 with my Flag Pole. The tuner belonged to a friend, and we were both curious to see how it would handle the Flag Pole. As I recall, it did find a match on 80 through 10, but it seems to me that it had a real hard time doing so on some bands. The native SWR on the antenna is quite high on some bands, presenting a greater challenge. I do not own an amp so I can't answer all your questions. I may have mentioned that I am now using an older Palstar AT-AUTO, and it works extremely well. It is not as fast as the Elecraft, but all I do is press the XMIT button on the K3 and the tuner finds a match in a very "reasonable" time, at about 10 watts. I do not have a lot of room on my desk, and as I believe I mentioned, I placed the tuner closer to the antenna than my shack. I have a 40' run of coax to the tuner, and then 30' from the tuner to the un-un at the antenna. From the day it was installed, it has been 100% RELIABLE when changing bands. I also borrowed a 500 watt tuner from a friend, and the tuner handles that power very well. In fact, I briefly tried a Ten-Tec Titan at 1000 watts, and at 1500 watts. On most bands the tuner handled that power very well, but one 80 meters, the power out and SWR jumped around a bit, making me believe that there was some arcing in the un-un, the tuner, or the amp. If it had been in the amp, I believe I would have heard it... I backed off the power at once. At 800 watts it was stable, but I was afraid to take it up higher again... afterall the amp was not mine, and I did not want to replace the tuner or the un-un. When you get the antenna installation complete, I would recommend that you carefully plot and record the SWR on all bands, without a tuner. Be sure to use a "good" SWR bridge, watt meter, or antenna analyzer. Then look at that information and you well get a good idea if the KAT500 will likely be able to handle it. If your SWR curves are like mine, you may find that on "some" bands the numbers fall outside of the indicated tuning range of the KAT500. I did not try the KAT500 at the place in my coax that my Palstar tuner is located... just on my desk by the K3. When I get a KPA500, I will may borrow a KAT500 and try that combination. At first I thought that not having INSTANT band change capability would be a negative... but I am not into contests, just casual DX and lots of rag chews. I do want more power than 100 watts, but I think I am going to stick with this tuner. In fact, the friend who had the Titan amplifier has two of the Palstar tuners. He has asked me to help sell one of them. If I did not already own this one, I would buy his... HI. I realize that I could not fully answer all your questions, but perhaps this has been of some help. Very 73 de Dave - K9FN ______________________________________________________________ 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
