David, The old timers used to use feedthru insulators to make a balanced line antenna connection thru walls - I don't know where to obtain those old large ceramic feedthrus anymore, but you can substitute with some other type of insulator - space your improvised feedthrus 3 to 4 inches apart, use a brass threaded rod for the conducting and fastening part and put nuts on both sides - your feedline connects on the outside to the threaded rods and on the inside, you run from the threaded rod to the tuner with another length of feedline.
The other alternative is to go through the wall with shielded balanced line. You make that from two paralleled lengths of coax - the two center conductors connect to the balanced feedline and you ground the shields. Use low loss coax because the losses due to high SWR are still present, and if running high power, be certain the voltage rating of the coax is adequate for the highest RF voltage you will encounter on your balanced feedline. As an additional note - you can cross a metallic boundary with parallel feedline with no problem to the RF as long as it occurs at right angles to the feedline - again be careful that you have adequate insulation where you cross, the RF voltages can be quite high even with low or moderate power if the feedline has a high SWR. 73, Don W3FPR > -----Original Message----- > > Here's another question for the antenna gurus. I would like to > use a balanced > feeder feeder for a multiband dipole. The problem is that my > shack is in a > steel shed and we all know running a balanced feedline near metal > objects is > a no-no. So, is there a way of getting a balanced feedline from > my antenna > to my balanced antenna tuner through steel? Also, my antenna is > away from > the shed so the feedline would not approach the shed at a perpendicular > angle. > > 73 de David VK5DG > K2 S/N 5492 > -- No virus found in this outgoing message. Checked by AVG Free Edition. Version: 7.5.441 / Virus Database: 268.18.2/692 - Release Date: 2/18/2007 4:35 PM _______________________________________________ Elecraft mailing list Post to: Elecraft@mailman.qth.net 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
