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#11
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using an MFJ-941E tuner on all bands?
James barrett wrote:
... should my thinking be to put up a dipole for 80m and tune it down to 10, 15 and 40, or should I go with some other length? An 80m dipole works well on all HF bands. I tune my 80m dipole system by varying the length of the ladder- line so I don't even need an antenna tuner. http://www.w5dxp.com/notuner.htm My favorite bands are 40m and 17m. -- 73, Cecil http://www.w5dxp.com |
#12
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using an MFJ-941E tuner on all bands?
On Nov 26, 7:22 pm, "Sal M. Onella"
wrote: I added two 20m elements of #16 insulated stranded wire (lamp cord, actually) and ran them downslope toward opposite corners of the garage roof. They make about a 45-degree angle with the 10m antenna. Construction articles encourage separating elements of different bands. The first measured 20m elements were too long and the SWR dipped at 12-something MHz. I trimmed them to 14.1 MHz, SWR = 1.1:1 at the radio. The only change to the 10m performance was a very slight increase in SWR (1.5:1 vs. 1.7:1 per MFJ-269). Hi, I don't understand how you can add elements to an existing antenna and have it still work on the band it was originally made for. Do you still need a tuner? Or do you remove the 20m elements to transmit on 10m? Jim |
#13
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using an MFJ-941E tuner on all bands?
On Nov 27, 3:43 am, "Jeff" wrote:
My naive understanding was that I could hang up a 100ft dipole and use a tuner to transmit on all bands. I find that set up extremely lossy on 10GHz Jeff Yikes, I don't have anything higher than a 2 meter HT. |
#14
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using an MFJ-941E tuner on all bands?
On Nov 26, 5:16 pm, Danny Richardson wrote:
Jim, Check this one out. http://www.degendesigns.com/Downloads/TheEasyWay.PDF Danny, K6MHE Hi, I like the article. One question about feed lines. If coax is 50 ohms and twin lead has 300 ohms. Why is the twin lead consideres less lossy than coax? I had thought that higher ohms meant higher impedance and I thought higher impedance means higher loss. Obviously I have not read the chapter on transmission lines yet ;-), so I may have that all wrong. Also, in the article, I liked the part about before 1950, no one even heard about swr, and that antennas with high swr were working just fine. But I make 2 assumptions: 1) I'm thinking, even if they didn't know or care about swr, they still had to cut their dipoles for the band they were transmitting on. 2) I still would not want to use a 10m dipole and transmit 100 watts on 80 without at least using a tuner. Am I correct in these assumptions? |
#15
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using an MFJ-941E tuner on all bands?
I just read this article from ARRL:
http://www.arrl.org/tis/info/pdf/9312070.pdf This is exactly what I want to do. Put up a single dipole that I can use reasonably well on HF bands. The thing I haven't figured out yet about ladder line yet is how to bring it in to the house. My current setup is a 10m dipole with RG58 coax feed line shoved under the back door. Obviously I can't do that with ladder line (aluminum door). I think I might get away with drilling two holes in the wall and putting in connectors, then attach the ladder line to the connectors. On the other side of the wall.... would I still want to use ladder line to continue on into the tuner? Or would would I want to attach a coax at that point from the wall to the tuner? Or maybe I need to hang my tuner on the wall. I'll google around and see what other people are doing, but I'd like to hear some ideas if anyone here is using ladder line. (should I change the topic for this thread?) Cecil, I love your no tuner ladder line idea. I think someday I'll try that when I have more experience with feed lines and antennas. jim |
#16
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using an MFJ-941E tuner on all bands?
On Tue, 27 Nov 2007 07:35:07 -0800 (PST), James barrett
wrote: Hi, I don't understand how you can add elements to an existing antenna and have it still work on the band it was originally made for. Do you still need a tuner? Or do you remove the 20m elements to transmit on 10m? Hi Jim, Adding a new band's element will likely disturb the performance of an existing one. However, it will be slight, and if you anticipate this, you can construct a two band antenna and tune both. Similarly, you can construct three, four, five.... band antennas using similar principles. There is, of course, the compounding of difficulty as you increase this count, but that doesn't preclude it being done successfully. 73's Richard Clark, KB7QHC |
#17
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using an MFJ-941E tuner on all bands?
On Tue, 27 Nov 2007 07:55:57 -0800 (PST), James barrett
wrote: Why is the twin lead consideres less lossy than coax? Hi Jim, All loss is in the bulk of the conductor. When comparing the two, twin lead usually has more bulk = less loss. I had thought that higher ohms meant higher impedance and I thought higher impedance means higher loss. Obviously I have not read the chapter on transmission lines yet ;-), so I may have that all wrong. You do. Impedance restricts energy, it doesn't consume it (loss). Also, in the article, I liked the part about before 1950, no one even heard about swr, and that antennas with high swr were working just fine. This is much the same illusion of climbing into a car with the speedometer exclusive marked in kM/h and thinking it has great 0-60 acceleration. Everything is just fine (ignorance is bliss). But I make 2 assumptions: 1) I'm thinking, even if they didn't know or care about swr, they still had to cut their dipoles for the band they were transmitting on. You don't even have to do that now, much less before 1950. Resonance merely simplifies things and gives you a benchmark for performance. If you don't have resonance, you accommodate to re-achieve that benchmark for performance (this is how it is done now, and how it was done before 1950). 2) I still would not want to use a 10m dipole and transmit 100 watts on 80 without at least using a tuner. Am I correct in these assumptions? That would be a pretty good intuition to proceed along. In this specific case, you may even stand to lose power with the best of tuners. Further correspondence will reveal those pitfalls. 73's Richard Clark, KB7QHC |
#18
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using an MFJ-941E tuner on all bands?
On Tue, 27 Nov 2007 08:54:24 -0800 (PST), James barrett
wrote: I think I might get away with drilling two holes in the wall and putting in connectors, then attach the ladder line to the connectors. Hi Jim, Good plan. Check to make sure you don't have foil backed insulation in the walls that might provide a short circuit path. On the other side of the wall.... would I still want to use ladder line to continue on into the tuner? You can do that. Or would would I want to attach a coax at that point from the wall to the tuner? You can do that too, but it is not a matter of "wanting to." Or maybe I need to hang my tuner on the wall. Only if you can reach it as part of your typical operating behavior. 73's Richard Clark, KB7QHC |
#19
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using an MFJ-941E tuner on all bands?
On 2007-11-27, James barrett wrote:
I just read this article from ARRL: http://www.arrl.org/tis/info/pdf/9312070.pdf This is exactly what I want to do. Put up a single dipole that I can use reasonably well on HF bands. The thing I haven't figured out yet about ladder line yet is how to bring it in to the house. My current setup is a 10m dipole with RG58 coax feed line shoved under the back door. Obviously I can't do that with ladder line (aluminum door). I think I might get away with drilling two holes in the wall and putting in connectors, then attach the ladder line to the Have the ladder line go to a ferrite bead balun (converts balanced to unbalanced) and a short piece of coax into the house and directly to the tuner. (Walt Maxwell's idea) I use this on my 80m loop and it tunes 80-10m easily. ....Edwin -- __________________________________________________ __________ "Once you have flown, you will walk the earth with your eyes turned skyward, for there you have been, there you long to return."-da Vinci http://bellsouthpwp2.net/e/d/edwinljohnson |
#20
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using an MFJ-941E tuner on all bands?
James barrett wrote:
I just read this article from ARRL: http://www.arrl.org/tis/info/pdf/9312070.pdf This is exactly what I want to do. Put up a single dipole that I can use reasonably well on HF bands. The thing I haven't figured out yet about ladder line yet is how to bring it in to the house. Lots of ways. In my house, I made a hole below the window that I can cover with a plate if I move. Some folks use Plexiglas for one of their windows and drill holes and make jumpers. IIRC Cecil's web pages have a nice illustration of that. You won't need as many holes if you make a regular dipole of course. My current setup is a 10m dipole with RG58 coax feed line shoved under the back door. Obviously I can't do that with ladder line (aluminum door). I think I might get away with drilling two holes in the wall and putting in connectors, then attach the ladder line to the connectors. Yep, that will work. On the other side of the wall.... would I still want to use ladder line to continue on into the tuner? Or would would I want to attach a coax at that point from the wall to the tuner? Run the ladder line the whole way to the tuner. Some folks put a balun in line and run coax for the last few feet, but the mfj has a balun built in. Or maybe I need to hang my tuner on the wall. heh, that would be good for excercising! I'll google around and see what other people are doing, but I'd like to hear some ideas if anyone here is using ladder line. (should I change the topic for this thread?) Nah, it's pretty much still on topic. One of the first things though is that there is ladder line, and there is window line. Most of us use window line, although ladder line has some advantages. Window line is easier to handle, and should work just fine for you. It is the poly coated stuff with cut out windows in it- hence the name. Cecil, I love your no tuner ladder line idea. I think someday I'll try that when I have more experience with feed lines and antennas. My xyl won't let me put one of those in - says it's visually challenged. - 73 de Mike N3LI - |
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