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#1
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20m is especially good. I have a 20m dipole and I answered a CQ from
Eastern Russia (4200+ miles) and Viktor RU0ZM, came right back to me. Then I noticed I was on tune power, 10W. Great night. "Sal" |
#2
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On Sat, 28 Apr 2012 21:11:30 -0700, "Sal" wrote:
20m is especially good. I have a 20m dipole and I answered a CQ from Eastern Russia (4200+ miles) and Viktor RU0ZM, came right back to me. Then I noticed I was on tune power, 10W. Great night. "Sal" Thanks. I turn on my ancient Icom IC-735, tune around 20 meters and hear nothing. Transmit and I get infinite VSWR. Ok, something is wrong. After 15 minutes of juggling coax cables, spinning knobs, pushing buttons, and head banging, the light comes on in my head. After a nasty wind storm in January, I a tree had destroyed most of my antenna farm, which I haven't repaired. Rebuild antennas now added to the things to do list. -- Jeff Liebermann 150 Felker St #D http://www.LearnByDestroying.com Santa Cruz CA 95060 http://802.11junk.com Skype: JeffLiebermann AE6KS 831-336-2558 |
#3
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![]() "Jeff Liebermann" wrote in message ... After a nasty wind storm in January, I a tree had destroyed most of my antenna farm, which I haven't repaired. Rebuild antennas now added to the things to do list. -- Jeff Luckily,in SoCal we don't contend with that very often -- Santa Ana winds in the canyons being the occasional exception. I feel for you. Meanwhile, just hang up any old thing and agitate some 'trons. A 20m dipole at 15 feet (one end tied off to my chimney and the other end to a branch in my neighbor's macadamia nut tree) is all I have or apparently need. Yes, 1 KW into a SteppIR on a 50 foot tower is better, but at a cost of several thousand dollars per S-unit. Really, it's all good. Maybe you heard my long-ago story about my 20m first-ever QSO with Hawaii. I got a 5-9 but the antenna was primitive: an existing 10m vertical dipole, with one end clipped to an extension ladder laying on the ground. True. "Sal" (KD6VKW) |
#4
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On Sun, 29 Apr 2012 12:13:28 -0700, "Sal" wrote:
Luckily,in SoCal we don't contend with that very often -- Santa Ana winds in the canyons being the occasional exception. I feel for you. The winds wasn't that bad. I live in a redwood, fir, oak, and madrone forest, which blocks most of the wind. The problems are caused by falling trees and limbs. I have a fair size ding in my car hood, and had an oak tree land on my flat roof, destroying most of my antennas and trashing in a skylight. Most of the shock was absorbed by my neighbors roof. http://802.11junk.com/jeffl/pics/2011-12-03-Storm/ So much for the idyllic life in the forest. Meanwhile, just hang up any old thing and agitate some 'trons. A 20m dipole at 15 feet (one end tied off to my chimney and the other end to a branch in my neighbor's macadamia nut tree) is all I have or apparently need. Yes, 1 KW into a SteppIR on a 50 foot tower is better, but at a cost of several thousand dollars per S-unit. There's no way I can rotate a horizontal antenna without hitting a tree or the hillside behind my house. A tower might help, if it were 200ft high, and the swaying trees won't hit the antenna. I'm stuck with using wire antennas and verticals. Really, it's all good. Maybe you heard my long-ago story about my 20m first-ever QSO with Hawaii. I got a 5-9 but the antenna was primitive: an existing 10m vertical dipole, with one end clipped to an extension ladder laying on the ground. True. Yep, RF is magic. I managed to make a QSO into a Heathkit Cantenna, but that's about the limits of my non-traditional antenna experiments. One of these days, I'm going to build an NEC2 model of an aluminum ladder and see what can be done to use it on VHF or UHF. So, I climbed up on my roof with a balun and some wire, intending to make a dipole. Normally, this is a trivial exercise. However, there's a problem. All the labels have peeled off my multitude of coax cables. The labels were UV proof but apparently not water proof. Almost all of my coax cables came off the same roll of RG6a/u and look identical. This is going to be a problem. I did manage to find all the parts to a Radio Shock discone antenna, which is now simulating a wet noodle on top of a 10ft 3/4" PVC pipe. That's because I can't find a single 10ft mast section that doesn't have a fatal dent or bend. The 12ft(?) long VHF/UHF Comet fiberglass antenna survived the tree fall, but will need to come down for some cleaning. The outside is covered with green slime. Experience has shown that when the outside is covered with green slime, so is the inside. Maybe I should give up for the day, and just clean up the workbench. -- Jeff Liebermann 150 Felker St #D http://www.LearnByDestroying.com Santa Cruz CA 95060 http://802.11junk.com Skype: JeffLiebermann AE6KS 831-336-2558 |
#5
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On Sun, 29 Apr 2012 14:07:22 -0700, Jeff Liebermann
wrote: I did manage to find all the parts to a Radio Shock discone antenna, which is now simulating a wet noodle on top of a 10ft 3/4" PVC pipe. That's because I can't find a single 10ft mast section that doesn't have a fatal dent or bend. The 12ft(?) long VHF/UHF Comet fiberglass antenna survived the tree fall, but will need to come down for some cleaning. The outside is covered with green slime. Experience has shown that when the outside is covered with green slime, so is the inside. Maybe I should give up for the day, and just clean up the workbench. Scale back a little.... I put up a fan inverted -V cut for 80-40-30 a while back just to test. I use a tuner, as long as the transmitter likes it, I like it. I hardly ever use 80m, no particular reason, I just don't. The ends droop to whatever was convenient. I did not bother to consider anything permanent. Most of the ends are secured at the perimeter of the yard via nylon braided line attached to military surplus fiber glass mast sections leaning into convenient trees. I only worried about keeping the ends high enough to avoid contact with people, tractors and deer in the yard. It seems to work well on all bands I have tried. Although I prefer my manual MFJ tuner, the internal tuner in my TenTec Jupiter seems to do OK. I am not a contester, a DX hound or a perfectionist but I do like to spend a little time on the air. I would make up a coax balun of about 8 turns of coax on a milk jug with connectors appropriate to the roof connections. The Dollar Store here sells black vinyl tape for about $1 for two rolls so wrap the balun up well enough to not become a future problem. Pick any cable handy on the roof, assuming that they all go to the shack. When you get to the shack, use the cable that has signals on it. I don't know which direction is favored on any band nor do I really have any idea which elements are active under any given circumstance. It will keep you on the air and give you time to decide where you want to go from here with out undue pressure! John Ferrell W8CCW |
#6
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On Mon, 30 Apr 2012 12:18:29 -0400, John Ferrell
wrote: I put up a fan inverted -V cut for 80-40-30 a while back just to test. I use a tuner, as long as the transmitter likes it, I like it. If it's anywhere near a 1/2 wave dipole, a fan dipole shouldn't need a tuner. I've built two fan dipoles over the years. Since everything affects everything else, I spent far too much time adjusting the wire lengths. I eventually settled on a trapped dipole, which was easier and worked the first time. Either antenna would work for me except for the length. I don't have the room for a proper 80 meter dipole. For the immediate problem, I'll be happy if I can get on 20 meters (PSK31) and 10 meters (radio club net). It seems to work well on all bands I have tried. Although I prefer my manual MFJ tuner, the internal tuner in my TenTec Jupiter seems to do OK. Antenna tuners can be quite lossy. Have fun with this Java app: http://fermi.la.asu.edu/w9cf/tuner/tuner.html Do you have a field strength meter? Find a location in the pattern and as far away as practical. View the meter from your operating position using binoculars or a telescope. Try your fan dipole directly to the 50 ohm output of your transmitter. Hopefully, the VSWR will be less than what it takes to trip the VSWR protection circuitry. Now, install the antenna tuner and try again, keeping the RF power at the same level. If you have problems leveling the RF power, use an AC powermeter, such as a Kill-a-Watt, to measure the AC input power consumption. When I did the same test, the antenna tuner always had noticeably less TX signal strength. I am not a contester, a DX hound or a perfectionist but I do like to spend a little time on the air. I spend more time inside the radios than in front of them. It will keep you on the air and give you time to decide where you want to go from here with out undue pressure! The answer for me was supplied by outside influences. A mess of work arrived at my shop, so I'll be too busy to do antennas for a while. -- Jeff Liebermann 150 Felker St #D http://www.LearnByDestroying.com Santa Cruz CA 95060 http://802.11junk.com Skype: JeffLiebermann AE6KS 831-336-2558 |
#7
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On Sat, 28 Apr 2012 21:11:30 -0700, Sal wrote:
20m is especially good. I have a 20m dipole and I answered a CQ from Eastern Russia (4200+ miles) and Viktor RU0ZM, came right back to me. Then I noticed I was on tune power, 10W. Great night. "Sal" 20m was good yesterday as well, I made several European contacts in just a few minutes on PSK31 (from 4 land). |
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