Dan wrote: I was out in the woods of Oregon today (up by the coast range town of Jewell) with my KX 1 and a few different antennas. I used a long wire for a while, but then for the heck of it I set up a 40M inverted vee with my portable mast. The KXAT1 had no trouble with the long wire (and counterpoises) bringing it right down to 1:1, but no such luck with the dipole ( cut to resonate on 40, and fed w/RG 174).I've used this antenna a bunch w/ the K2 and it's pretty much a 1:1, but when using the KX1 atu I got around 9:5 SWR!
------------------------------------------------------- You should not have had any trouble with a center fed dipole, Dan. The issue with the KX1 ATU, as with any ATU, is impedance extremes. Because of the limited number of inductors and capacitors that could be fitted into the tiny space available in the KX1, it has a more limited tuning range than any of the other Elecraft tuners. The end of a dipole presents a very high impedance, possibly in the thousands of ohms. At the other extreme, a very short antenna will present a very low impedance, often less than an ohm. Actually, end-fed short antennas often tune up more easily because they are working against ground and typically Hams have lousy RF grounds <G>. Even with several "radials" the ground impedance will likely be in the tens or, more likely, the hundreds of ohms. That's in series with the antenna so what the tuner is matching is a total impedance of perhaps a hundred ohms or more. The fraction of an ohm that the antenna represents is just part of the total. It's also why such antennas have a very, very low efficiency: often less than a few percent. In your case, I'd suspect you had an unlucky length of feed line. Unless the SWR is truly 1:1 on that feeder, something that is almost never achieved in practice, the feed line acts like a random impedance transformer. I suspect you got unlucky and the combination of the effect of surrounding objects, antenna length, feeder impedance and feeder length all added up to an impedance the KX1 ATU couldn't handle. Adding a few feet of feed line will usually fix that. Another possibility is a short or open, as you suggested. Ron AC7AC _______________________________________________ Elecraft mailing list Post to: [email protected] You must be a subscriber to post to the list. Subscriber Info (Addr. Change, sub, unsub etc.): http://mailman.qth.net/mailman/listinfo/elecraft Help: http://mailman.qth.net/subscribers.htm Elecraft web page: http://www.elecraft.com
