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#1
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My current attic situation consists of a 20M dipole, a 30M and two 40M
MicroVerts, and an 80M Hamstick Dipole. Using a homebrew antenna switch, I can switch between all these and use a tuner in the shack to make everything look good. I was thinking of doing the following and am looking for opinions/sugestions/comments both good and bad. I would remove all the stuff above and run ~100 ft of 14G insulated solid copper house wire around the perimeter of the attic. Use the control cable for the switch to run a Icom AH-4 auto-tuner connected to the wire. The wire will be run in "T" figure (I'll forgo the ascii art). Basically; West ~15', North 15', East 10', North 15', East 10', South 15', East 10', South 15', and back West near the start of the run. I only have access to the metal conduit runs on the attic for ground. This is the setup I had, along with a homebrew balun to feed the coax) for my SWL days and it worked pretty well. I pulled the wire down when I put all the other stuff up there but can re-install in any configuration available. The longest straight run I can make is ~ 35' diagonally. Woulkd I be better off just running a straight piece rather then all the ziggin' and zaggin'?? How about putting it up as a big "Z" (25' West, 35' diagonally NE, then 20' East)?? Any inputs on this plan are appreciated befor I spend the $$ on the tuner. Thanks, Tom - AC9TS |
#2
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![]() "Tom S" wrote in message ... ...I was thinking of doing the following and am looking for opinions/sugestions/comments both good and bad. ...run ~100 ft of 14G insulated solid copper house wire around the perimeter of the attic. Use the control cable for the switch to run a Icom AH-4 auto-tuner connected to the wire. The wire will be run in "T" figure (I'll forgo the ascii art). Basically; West ~15', North 15', East 10', North 15', East 10', South 15', East 10', South 15', and back West near the start of the run. I only have access to the metal conduit runs on the attic for ground. [snip SWL talk] The longest straight run I can make is ~ 35' diagonally. Woulkd I be better off just running a straight piece rather then all the ziggin' and zaggin'?? How about putting it up as a big "Z" (25' West, 35' diagonally NE, then 20' East)?? Any inputs on this plan are appreciated befor I spend the $$ on the tuner. Thanks, Tom - AC9TS I'd go for the long run or perhaps a 90 degree "L" using the two longest possible lengths. 35' is close to a 1/2 wave on 20 and 2 halves on 10 making it harder to match (high Z) on those bands. It's nice to keep your antenna away from an even number of half waves so the impedance isn't too high. HOWEVER, using the conduit for "ground" means that IT WILL BE part of the antenna. It will probably be near the antenna. Not good. It is anther random variable. Not good. Not being "good" doesn't stop many of us. SO...RF is fickle...try it. -- Steve N, K,9;d, c. i My email has no u's. |
#3
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"Tom S" wrote:
My current attic situation consists of a 20M dipole, a 30M and two 40M MicroVerts, and an 80M Hamstick Dipole. Using a homebrew antenna switch, I can switch between all these and use a tuner in the shack to make everything look good. I was thinking of doing the following and am looking for opinions/sugestions/comments both good and bad. I would remove all the stuff above Leave the old antennas up there. That makes it easy and fun to make comparisons to see how well your new antenna does as compared to the old. and run ~100 ft of 14G insulated solid copper house wire around the perimeter of the attic... This sounds like you almost have a loop. You might consider trying a random length loop around the perimeter edge of the roof. one big advantage is that it requires no ground with which to work against. I have about 200' of wire in mine which peaks at about 20' up. I feed mine with ladder line, but for short runs coax is ok as the loss would be small. I lucked out because by using a 4:1 balun it turned out that my TS870's internal tuner is happy with it on all HF bands except 80 and 160. For those bands an external tuner works fine. It's no DX antenna, but I never have any trouble making or finishing QSOs. And compared to my 40M Hamstick attic dipole, the loop gets on average about a 2 s-unit better report. |
#4
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Tom and others,
I'm very interested in what you work out. I just moved into the city and have an old house with a big attic. There is really no place on the lot (very small 2500 sg ft lot) to put any antennas. The attic is the third floor the peak being 30-35 feet above ground. There is no metal in the attic accept one condiut for a light and the cast iron soil pipes for venting the drains. I have an AH-2 tuner that I am hoping I can make work with my kenwood TS- 690S. I do have a little ICOM 760 mobile that I will use if I absolutely have to but that's really for my car (not currently installed). So any thoughts on strait or loop. For strait I can go 50' Also should I run COAX from the main floor to the tuner in the attic and use the castiron soil pipe as ground OR should I have my 50' straight and then bring the antenna on the outside of the building down to ground level (inverted L) and keep the AH-2 in or very near the shack? Thanks, Kevin N9JKP posted and mailed] Any inputs on this plan are appreciated befor I spend the $$ on the tuner. Thanks, Tom - AC9TS This is the setup I had, along with a homebrew balun to feed the coax) for my SWL days and it worked pretty well. I pulled the wire down when I put all the other stuff up there but can re-install in any configuration available. The longest straight run I can make is ~ 35' diagonally. Woulkd I be better off just running a straight piece rather then all the ziggin' and zaggin'?? How about putting it up as a big "Z" (25' West, 35' diagonally NE, then 20' East)?? |
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