RE: [Elecraft] steel shed and balanced feed
Thanks Dave, your comment reminded me of L B Cebik's recommendation - which is to run coax through the shack wall and place a 1:1 current balun on the outside to feed the balanced line. 73, Don W3FPR > -Original Message- > I have an upstairs shack with a balanced feeder needing to pass through > a brick wall into the shack. I have a balun mounted on the outside wall > of the shack, hole drilled in the wall to take the feeder and a metre of > feeder to the K2. I use a 4:1 voltage balun in a plastic "project" box, > home wound and connected to the balanced feeder with brass nuts and > bolts. By using a 4:1 voltage balun (not ideal as a balun...) it has the > advantage of being able to provide a DC ground for both halves of the > doublet. > > Maybe your antenna/shack configuration doesn't lend itself to this idea, > but if it does it makes life very simple. > > 73 Dave, G4AON > K1 #1154, K2 #1892 > -- No virus found in this outgoing message. Checked by AVG Free Edition. Version: 7.5.441 / Virus Database: 268.18.3/694 - Release Date: 2/20/2007 1:44 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
Re: [Elecraft] steel shed and balanced feed
David I have an upstairs shack with a balanced feeder needing to pass through a brick wall into the shack. I have a balun mounted on the outside wall of the shack, hole drilled in the wall to take the feeder and a metre of feeder to the K2. I use a 4:1 voltage balun in a plastic "project" box, home wound and connected to the balanced feeder with brass nuts and bolts. By using a 4:1 voltage balun (not ideal as a balun...) it has the advantage of being able to provide a DC ground for both halves of the doublet. Maybe your antenna/shack configuration doesn't lend itself to this idea, but if it does it makes life very simple. 73 Dave, G4AON K1 #1154, K2 #1892 ___ 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
RE: [Elecraft] steel shed and balanced feed
Don and all: An assortment of ceramic feedthrus are still available at Surplus Sales of Nebraska. (Note: I have no financial interest in the company. I'm merely a happy customer.) 73, Steve Kercel AA4AK At 09:06 AM 2/20/2007, Don Wilhelm wrote: 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, ... ___ 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
Re: [Elecraft] steel shed and balanced feed
David You didn't mention what kind of openings, if any, already exist in the shed walls. Two things you can do. 1. Put a gradual twist in the feedline, say one revolution every six feet or so. This evens out the unbalancing due to the nearness of the metal shed. 2. Where you do find an opening to pass the line through, come in directly at right angles to the metal so that the line is only exposed to the edge of the metal as it passes through. I think I read somewhere that the opening should be about three times the width of the feedline, and the feedline should be centered in it. I live in a house with aluminum siding. In the garage, over my station table, I put a 2 inch diameter hole in the wall and covered it with an outdoor plastic entrance box. It has a hole in the bottom for feed lines to come through, while keeping rain out. Absolutely no problems so far, after five years. Good luck and 73 Bob N6WG The Little Station with Attitude - Original Message - From: "David" <[EMAIL PROTECTED]> To: Sent: Monday, February 19, 2007 10:01 PM Subject: [Elecraft] steel shed and balanced feed > Hello All, > > 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 > ___ > 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 ___ 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
Re: [Elecraft] steel shed and balanced feed
> So, is there a way of getting a balanced feedline from my antenna > to my balanced antenna tuner through steel? I'm about to try something I've heard about, but never done myself: use parallel lengths of coax with the shields connected but not grounded. This is supposed to provide 'safe passage' for a balanced signal. What I don't know about this is how much, if any, of an impedance bump it causes... 73 de chris K6DBG ___ 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
RE: [Elecraft] steel shed and balanced feed
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
