Home |
Search |
Today's Posts |
|
#1
|
|||
|
|||
"Richard Clark" wrote in message ... Hi Ken, Well, gee, I don't know how to put this, but I'd leave things alone. There is almost nothing you can do that would be measureable/noticeable from the other end in all likelihood -- unless everything worked only because your antenna was nothing more than an aircooled resistor. You could double your output and it would barely nudge their S-meter. Use an ordinary 1:1 Current BalUn (to answer your last question). Any other value (one feels compelled to suggest 1:9) would be just as bad over much of those frequencies as the 1:1 (except different frequencies). The upshot of using a Current BalUn is the benefit of its choking action and a 1:9 may not exhibit that as well; especially if it is a Voltage BalUn construction. 73's Richard Clark, KB7QHC Thanks for the info, Richard - I went to Eham.net and read the reviews on the all bander. Not all were good so I started looking at the other reviews for ideas. Found the MFJ-1788 G5RV antenna. I'm usually a bit suspicious about MFJ products but this one got good reviews. So, what do you think about the G5RV for my situation? The apex would be at 35' and the ends would be about 20' The 34' of ladder line would reach my window feedpoint just fine then I could make a coax choke (MFJ says 10 turns @ 4-6" dia) and then feed it to my LDG tuner. the coax run would be about 8'. A note on choke construction - I use plastic forms to wind the coax then glue the turns together with superglue and baking soda. I only have two smooth plastic forms avaiable - a 2-5/8" and a 5 inch. So, I could make a 10 turn, 5" dia choke for this new antenna. Your thoughts? Ken KG0WX |
#2
|
|||
|
|||
On Sun, 4 Jan 2004 08:51:34 -0700, "Ken Bessler"
wrote: Thanks for the info, Richard - I went to Eham.net and read the reviews on the all bander. Not all were good so I started looking at the other reviews for ideas. Found the MFJ-1788 G5RV antenna. I'm usually a bit suspicious about MFJ products but this one got good reviews. So, what do you think about the G5RV for my situation? The apex would be at 35' and the ends would be about 20' The 34' of ladder line would reach my window feedpoint just fine then I could make a coax choke (MFJ says 10 turns @ 4-6" dia) and then feed it to my LDG tuner. the coax run would be about 8'. A note on choke construction - I use plastic forms to wind the coax then glue the turns together with superglue and baking soda. I only have two smooth plastic forms avaiable - a 2-5/8" and a 5 inch. So, I could make a 10 turn, 5" dia choke for this new antenna. Your thoughts? Ken KG0WX Hi Ken, Your recipe for a choke sounds quite suitable. Keep in mind all such designs are optimized somewhere and marginal elsewhere. What you've described will undoubtedly do the job, peaking in the 20-30M bands and tapering to each side. The fact of the matter is that few measure where their chokes resonate (thus providing the greatest isolation) or how much Q they exhibit. Usually, the proof of isolation is found in performance. That is, did it clear up transmissions getting into the home electronics? If it did, no one will care the line still radiates - unless such lax isolation fills in nulls you need in a pattern to kill neighboring noise or strong stations. As for the G5RV. It was designed to a length to be suitably tuned in a majority of bands back in the stone age. Band plans have changed somewhat (WARC and all) to confound that claim. That aside, the combination of coax and ladder line was something of a marketing idea, you are just as well off by simply using ladder line all the way back to the tuner (or the BalUn heading into the tuner, make sure it is a Current BalUn design, as the ones inside tuners are mickey mouse Voltage designs). So, having stripped away the trademark coax/ladder combo, you can progress to the next step and simply erect the highest longest dipole and be done with it. You are going to be doing a tune-up anyway, so having excess length draped through trees and limping ground ward has no inherent merit. It won't hurt that much either, but no magical properties will be observed through what we call "appelation gain" (that extra 3dB because the vendor put a name to it like G5RV). A buddy of mine had the classic G5RV and it served suitably well (coming no where close to his beam where the bands overlapped) until one dark and stormy night when he encountered a higher than normal SWR against a lot of power. The BalUn rattled like a mariachi after that and the antenna was quite deaf. 73's Richard Clark, KB7QHC |
Reply |
Thread Tools | Search this Thread |
Display Modes | |
|
|
Similar Threads | ||||
Thread | Forum | |||
opinions of GAP Voyager | Antenna | |||
Opinions on Yaesu "ATAS" Mobile Antenna? (from experienced users, please) | Antenna | |||
Populating my tower from scratch... need opinions on antennas. | Antenna | |||
Opinions please G5 against long wire against windom? | Antenna |