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#11
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Buck wrote:
Now that auto-tuners are about as inexpensive as the manual tuners, I am awfully tempted to wander over to the SGC shelf at one of the ham stores and try it out. I am moving to a new house soon. We will be restricted in antennas only to the extent that we don't make the yard look too ugly. It isn't terribly well suited for many antennas, but I do hope to put up at least one decent fan-dipole, more accurately parallel dipole. I don't think I can fit a full-wave loop, due to lack of supports, but it looks like I'll have a place outside my window where a row of trees can support a 60 foot or so high dipole.... I still have a 100 foot roll of 300 or 450 ohm window line ![]() The advantage of the tuner with a "fan" or "parallel wire" dipole is that if you put it at the feedpoint, the incredibly tedious pruning process is eliminated. You just have to get a couple wires "about right", and the tuner does the rest (who cares if the resonance is at 13.5 MHz.. that's not a huge change). And, in the "thrown on the roof" sort of scenario, as the roof grunge and moisture changes or the trees grow up or get leaves on them, changing the native Z of the antenna, the tuner automatically compensates. It's a coax feedline, so it's easy to route. The matching is at the antenna, so the loss in the feedline is less of an issue. In this sort of thing it *is* useful to have some way to see if the antenna has fallen apart or shorted out or is covered with wet leaves. The tuner will happily tune almost anything, but you have no real way to know if it's actually radiating. I've used a couple techniques.. a monitor receiver with a whip antenna is one; looking at NCDXF beacons or WWV is another. |
#12
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On Mar 25, 11:32 am, Jim Lux wrote:
Buck wrote: Now that auto-tuners are about as inexpensive as the manual tuners, I am awfully tempted to wander over to the SGC shelf at one of the ham stores and try it out. I am moving to a new house soon. We will be restricted in antennas only to the extent that we don't make the yard look too ugly. It isn't terribly well suited for many antennas, but I do hope to put up at least one decent fan-dipole, more accurately parallel dipole. I don't think I can fit a full-wave loop, due to lack of supports, but it looks like I'll have a place outside my window where a row of trees can support a 60 foot or so high dipole.... I still have a 100 foot roll of 300 or 450 ohm window line ![]() The advantage of the tuner with a "fan" or "parallel wire" dipole is that if you put it at the feedpoint, the incredibly tedious pruning process is eliminated. You just have to get a couple wires "about right", and the tuner does the rest (who cares if the resonance is at 13.5 MHz.. that's not a huge change). And, in the "thrown on the roof" sort of scenario, as the roof grunge and moisture changes or the trees grow up or get leaves on them, changing the native Z of the antenna, the tuner automatically compensates. It's a coax feedline, so it's easy to route. The matching is at the antenna, so the loss in the feedline is less of an issue. In this sort of thing it *is* useful to have some way to see if the antenna has fallen apart or shorted out or is covered with wet leaves. The tuner will happily tune almost anything, but you have no real way to know if it's actually radiating. I've used a couple techniques.. a monitor receiver with a whip antenna is one; looking at NCDXF beacons or WWV is another. You can put your radio in a hand carry wire shopping basket and dispense with the transmission line. Wireless shopping no less. |
#13
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On Tue, 25 Mar 2008 09:32:51 -0700, Jim Lux
wrote: Buck wrote: Now that auto-tuners are about as inexpensive as the manual tuners, I am awfully tempted to wander over to the SGC shelf at one of the ham stores and try it out. I am moving to a new house soon. We will be restricted in antennas only to the extent that we don't make the yard look too ugly. It isn't terribly well suited for many antennas, but I do hope to put up at least one decent fan-dipole, more accurately parallel dipole. I don't think I can fit a full-wave loop, due to lack of supports, but it looks like I'll have a place outside my window where a row of trees can support a 60 foot or so high dipole.... I still have a 100 foot roll of 300 or 450 ohm window line ![]() The advantage of the tuner with a "fan" or "parallel wire" dipole is that if you put it at the feedpoint, the incredibly tedious pruning process is eliminated. You just have to get a couple wires "about right", and the tuner does the rest (who cares if the resonance is at 13.5 MHz.. that's not a huge change). And, in the "thrown on the roof" sort of scenario, as the roof grunge and moisture changes or the trees grow up or get leaves on them, changing the native Z of the antenna, the tuner automatically compensates. It's a coax feedline, so it's easy to route. The matching is at the antenna, so the loss in the feedline is less of an issue. In this sort of thing it *is* useful to have some way to see if the antenna has fallen apart or shorted out or is covered with wet leaves. The tuner will happily tune almost anything, but you have no real way to know if it's actually radiating. Actually, a field strength meter in the radio room works wonders. If it quits deflecting and you are pumping full power... oops. I've used a couple techniques.. a monitor receiver with a whip antenna is one; looking at NCDXF beacons or WWV is another. -- 73 for now Buck, N4PGW www.lumpuckeroo.com "Small - broadband - efficient: pick any two." |
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