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Bury balanced line?
For esthetic / XYL / neighboor reasons, I'm thinking of running balanced
"ladder" line to the back of my yard, via 1" PVC pipe with appropriate measures to keep the water out, and burying it maybe a foot underground. Length of the run might be 20 feet along the bottom of a deck and then 60 feet buried, give or take. Then straight up a tree centered between two other trees to feed about a 80' center fed dipole. Nothing else will be in the pipe with the feed line. Anyone have any thoughts on why this might or might not work? The ground where it could be buried, is on the moist side most of the year. Bob kb8tl |
Bob, I, for one, can't imagine any "easy" way to bury open feed line without at least some degredation. Were I in your shoes, I'd be thinking about coax to that tree and putting some kind of remote tuner out there. Ed K7AAT |
"Bob P" wrote in message ... For esthetic / XYL / neighboor reasons, I'm thinking of running balanced "ladder" line to the back of my yard, via 1" PVC pipe with appropriate measures to keep the water out, and burying it maybe a foot underground. Length of the run might be 20 feet along the bottom of a deck and then 60 feet buried, give or take. Then straight up a tree centered between two other trees to feed about a 80' center fed dipole. Nothing else will be in the pipe with the feed line. Anyone have any thoughts on why this might or might not work? The ground where it could be buried, is on the moist side most of the year. This may be an interesting experiment - and I for one will appreciate a report of your success. I would suggest trying it without burying it first - If it works above-grade, it may work buried. The biggest challenge will be keeping water out of the pipe. --- Outgoing mail is certified Virus Free. Checked by AVG anti-virus system (http://www.grisoft.com). Version: 6.0.818 / Virus Database: 556 - Release Date: 12/17/2004 |
Bob:
If I had to do what you are proposing, and could find no alternative, I would go purchase a bunch of the foam pipe insulation, experimentally determine what spacing 6" chunks of it would still support the line adequately centered in the pipe, and put that in 1-¼" or 1-½" pipe, whichever it fit the best. Bigger is better as someone else pointed out. You might want to test some for RF loss, as the black version may well contain carbon. Styrofoam would be the best choice, but I don't know of a cylindrical form of Polystyrene foam. Maybe 1" strips of it cut from 4' X 8' sheets of 1" foam would work. Use your imagination, for gosh sakes. The PVC will survive underground satisfactorily, but paint the exposed ends for longest life (or use short pieces of gray conduit for the exposed portion). -- Crazy George Remove N O and S P A M imbedded in return address "Bob P" wrote in message ... For esthetic / XYL / neighboor reasons, I'm thinking of running balanced "ladder" line to the back of my yard, via 1" PVC pipe with appropriate measures to keep the water out, and burying it maybe a foot underground. Length of the run might be 20 feet along the bottom of a deck and then 60 feet buried, give or take. Then straight up a tree centered between two other trees to feed about a 80' center fed dipole. Nothing else will be in the pipe with the feed line. Anyone have any thoughts on why this might or might not work? The ground where it could be buried, is on the moist side most of the year. Bob kb8tl |
Bob, KB8TL wrote:
"Anyone have any thoughts on why this might not work?" I`ve worked in several medium wave broadcast stations which used buried coax to feed the towers. No problems.. I worked in a shortwave broadcast plant where we needed a 100 KW dummy load. So we constructed a parallel wire 600-ohm line only about 2 feet above the earth using Copperweld wires a few hundred feet long. It could boil the dew on the groud and bring earth worms to the surface. It also did a great job of dissipating the 100 KW. Anytime parallel line such as twinlead or ladderline approaches ordinary earth, loss soars. Direct burial is impractical even inside fairly large conduit. Use one or two lengths of waterproof coax as buried line. Best regards, Richard Harrison, KB5WZI |
Could you not create low loss "coax" by using concentric pipes? Might be easier than all this hacking around.. That, or run heliax in the buried section, and convert to balanced in a little box on the other end. |
"Dave VanHorn" wrote in message ... Could you not create low loss "coax" by using concentric pipes? Might be easier than all this hacking around.. They call that hard line, as in Heliax etc. W4OP |
And I thought it were only Black pudding that came from Bury...
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Bob,
The 'quick'n'dirty' answer is don't waste your time burying the ladder line. If you have to bury a feed line make it coax (one of the reasons it was invented, to be able to run it close to 'stuff', or ground). Still want to try it? Then why not. The losses may be acceptible to you (sort of doubt that, but...), and it would be an interesting experiment. 'Doc ALTERNATIVE #1 Take up metal welding 'scupture'. Build a huge ~ugly~ thingy in the backyard. Hang dipole over the top of it (call it a lightning protection device). 'They' will be so upset over the 'sculpture' they'll never even see the dipole. Invest in a good divorce attorney. |
Richard Harrison wrote:
Anytime parallel line such as twinlead or ladderline approaches ordinary earth, loss soars. Direct burial is impractical even inside fairly large conduit. Use one or two lengths of waterproof coax as buried line. A ham I know uses parallel runs of buried RG62 as a compromise. That gives him a characteristic impedance of 186 ohms for his 30 foot underground section. It was interesting to model that setup using MicroSmith. -- 73, Cecil http://www.qsl.net/w5dxp ----== Posted via Newsfeeds.Com - Unlimited-Uncensored-Secure Usenet News==---- http://www.newsfeeds.com The #1 Newsgroup Service in the World! 100,000 Newsgroups ---= East/West-Coast Server Farms - Total Privacy via Encryption =--- |
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