It's very hard to say, Jim, because that sort of antenna will show a huge range of possible impedance values at the transmitter depending upon the feeder length. An unmatched feeder like that acts as an impedance transformer based on its length. That's why you so often see comments like "change the feeder length if the tuner can't find a match". (I suspect most people who suggest that never tried to figure out what to do with excess balanced line, even "twinlead"!)
Another approach many use is to add a 4:1 balun at the rig. Or switch a balun between 1:1 and 4:1 (Elecraft makes such a balun whose ratio can be changed by throwing a switch). That often does the job because it does the same thing as changing the length of the feeder: the impedance the rig sees is different and, hopefully, within in the tuning range of the ATU. Your MFJ tuner has a much wider matching range than just about any other design. That's the good side of a T-network tuner. (The negative side is that it can be very lossy if not adjusted according to the instructions or if it must match a very low impedance. With your 40 meter antenna, the impedance isn't likely to be low enough to be an issue on any band from 3.5 MHz up. ) Elecraft uses an L-network which is also very, very good, and very low loss but it doesn't replicate the whole range of your T-match network. So it's possible it may not provide a good match on ALL bands without providing a balun or changing the length of the feeder. Ron AC7AC -----Original Message----- This is a test message and a question. If the message gets through, that part works fine. Now for the question: My current QTH is a city lot that has several large oak trees in the back yard. The trees have been there over 30 or 40 years and I will not be able to do much more than trim a very few limbs that get too close to other structures. My HF antenna at present is an inverted V configuration hung from one of the trees at about 40 feet off the ground (also the yard is not level, there are several slopes) and the end points tied to another tree on one side of the yard and a fence on the other side. The antenna was cut for 40 meters. The feed line is an unknown length of 300 ohm television twin lead coming into the attic then through a closet to the radio. My current radio (not an Elecraft) has an MFJ-941B tuner between the antenna connection and the actual feed line. Would the K2 with an internal ATU be able to work with this antenna/feed line combination? Thank you, Jim KD5VXH _______________________________________________ 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
