There
I tried to get on 160 with my Inverted L last night. 60 feet up and the rest over to a tree, 130 feet total. About 20 random length radials in the yard. The best I can do with a city lot. This antenna worked last year very well, but now I get this 12/1/2018 10:46:08 AM NOTES: Frequency SWR --------- --- 001800000 1.3 001810000 1.4 001820000 1.4 001830000 1.4 001840000 1.4 001850000 1.5 001860000 1.6 001870000 1.6 001880000 1.5 001890000 1.5 001900000 1.6 001910000 1.6 001920000 1.6 001930000 1.6 001940000 1.6 001950000 1.6 001960000 1.6 001970000 1.7 001980000 1.8 001990000 2.0 002000000 2.1 There seems to be NO resonance at all with this antenna. Before, I could operate the bottom of the band but nothing above 1850 without a tuner. I have changed out the coax feeding the antenna which hepl bring signals up, but it seems to be a dummy load. Anyone have an idea what is going on? Shucks, I am out of ideas. Unless my ground plane has gone wonky My tuner can't find a match for it either. I have an automatice tuner now, but it cannot find a match. Something is wrong here and I am stumped. Any help from the antenna gurus out there? Lee - K0WA ______________________________________________________________ Elecraft mailing list Home: http://mailman.qth.net/mailman/listinfo/elecraft Help: http://mailman.qth.net/mmfaq.htm Post: mailto:[hidden email] This list hosted by: http://www.qsl.net Please help support this email list: http://www.qsl.net/donate.html Message delivered to [hidden email] |
1. The resonant point seems to be at 1.80 or below.
2. The broad response indicates high loss somewhere. If you hadn’t said that you changed it, I would suspect water in the coax. Victor 4X6GP > On 1 Dec 2018, at 18:54, Leroy Buller <[hidden email]> wrote: > > There > I tried to get on 160 with my Inverted L last night. 60 feet up and the > rest over to a tree, 130 feet total. About 20 random length radials in the > yard. The best I can do with a city lot. This antenna worked last year > very well, but now I get this > > 12/1/2018 10:46:08 AM NOTES: > > Frequency SWR > --------- --- > 001800000 1.3 > 001810000 1.4 > 001820000 1.4 > 001830000 1.4 > 001840000 1.4 > 001850000 1.5 > 001860000 1.6 > 001870000 1.6 > 001880000 1.5 > 001890000 1.5 > 001900000 1.6 > 001910000 1.6 > 001920000 1.6 > 001930000 1.6 > 001940000 1.6 > 001950000 1.6 > 001960000 1.6 > 001970000 1.7 > 001980000 1.8 > 001990000 2.0 > 002000000 2.1 > > There seems to be NO resonance at all with this antenna. Before, I could > operate the bottom of the band but nothing above 1850 without a tuner. I > have changed out the coax feeding the antenna which hepl bring signals up, > but it seems to be a dummy load. > > Anyone have an idea what is going on? Shucks, I am out of ideas. Unless > my ground plane has gone wonky > > My tuner can't find a match for it either. I have an automatice tuner now, > but it cannot find a match. Something is wrong here and I am stumped. > > Any help from the antenna gurus out there? > > Lee - K0WA > ______________________________________________________________ > Elecraft mailing list > Home: http://mailman.qth.net/mailman/listinfo/elecraft > Help: http://mailman.qth.net/mmfaq.htm > Post: mailto:[hidden email] > > This list hosted by: http://www.qsl.net > Please help support this email list: http://www.qsl.net/donate.html > Message delivered to [hidden email] Elecraft mailing list Home: http://mailman.qth.net/mailman/listinfo/elecraft Help: http://mailman.qth.net/mmfaq.htm Post: mailto:[hidden email] This list hosted by: http://www.qsl.net Please help support this email list: http://www.qsl.net/donate.html Message delivered to [hidden email] |
In reply to this post by Leroy Buller
Lee …
You’re on the right track with changing the coax. You have some sort of resistive loss. As you note, the “bandwidth” is much higher than it should be. My inverted L had a 2:1 SWR bandwidth of perhaps 35 KHz at most. Your low SWR across the entire band indicates very low efficiency and some sort of loss element(s). After the coax, I’d look at connectors, insulators, etc. etc. Do you have any feed-thrus, suppressors, or other things in the feed system? I’d suggest first checking the SWR and bandwidth right at the antenna base with the coax disconnected. Use a portable instrument. Good Luck! 73 Craig AC0DS > On 1, Dec2018, at 9:54 AM, Leroy Buller <[hidden email]> wrote: > > There > I tried to get on 160 with my Inverted L last night. 60 feet up and the > rest over to a tree, 130 feet total. About 20 random length radials in the > yard. The best I can do with a city lot. This antenna worked last year > very well, but now I get this > > 12/1/2018 10:46:08 AM NOTES: > > Frequency SWR > --------- --- > 001800000 1.3 > 001810000 1.4 > 001820000 1.4 > 001830000 1.4 > 001840000 1.4 > 001850000 1.5 > 001860000 1.6 > 001870000 1.6 > 001880000 1.5 > 001890000 1.5 > 001900000 1.6 > 001910000 1.6 > 001920000 1.6 > 001930000 1.6 > 001940000 1.6 > 001950000 1.6 > 001960000 1.6 > 001970000 1.7 > 001980000 1.8 > 001990000 2.0 > 002000000 2.1 > > There seems to be NO resonance at all with this antenna. Before, I could > operate the bottom of the band but nothing above 1850 without a tuner. I > have changed out the coax feeding the antenna which hepl bring signals up, > but it seems to be a dummy load. > > Anyone have an idea what is going on? Shucks, I am out of ideas. Unless > my ground plane has gone wonky > > My tuner can't find a match for it either. I have an automatice tuner now, > but it cannot find a match. Something is wrong here and I am stumped. > > Any help from the antenna gurus out there? > > Lee - K0WA > ______________________________________________________________ > Elecraft mailing list > Home: http://mailman.qth.net/mailman/listinfo/elecraft > Help: http://mailman.qth.net/mmfaq.htm > Post: mailto:[hidden email] > > This list hosted by: http://www.qsl.net > Please help support this email list: http://www.qsl.net/donate.html > Message delivered to [hidden email] ______________________________________________________________ Elecraft mailing list Home: http://mailman.qth.net/mailman/listinfo/elecraft Help: http://mailman.qth.net/mmfaq.htm Post: mailto:[hidden email] This list hosted by: http://www.qsl.net Please help support this email list: http://www.qsl.net/donate.html Message delivered to [hidden email] |
Like other have said, when you 160M antenna looks this broad, you have a
problem. :) Somewhere you ground losses have increase and that results in what you are seeing. Can you take an antenna analyzer to the base of the antenna and see if you see the same thing? If you don't, then change the coax. If you do, then check your feed points. Mike va3mw On Sat, Dec 1, 2018 at 12:07 PM Craig Smith <[hidden email]> wrote: > Lee … > > You’re on the right track with changing the coax. You have some sort of > resistive loss. As you note, the “bandwidth” is much higher than it should > be. My inverted L had a 2:1 SWR bandwidth of perhaps 35 KHz at most. > Your low SWR across the entire band indicates very low efficiency and some > sort of loss element(s). > > After the coax, I’d look at connectors, insulators, etc. etc. Do you > have any feed-thrus, suppressors, or other things in the feed system? > > I’d suggest first checking the SWR and bandwidth right at the antenna base > with the coax disconnected. Use a portable instrument. > > Good Luck! > > 73 Craig AC0DS > > > On 1, Dec2018, at 9:54 AM, Leroy Buller <[hidden email]> wrote: > > > > There > > I tried to get on 160 with my Inverted L last night. 60 feet up and the > > rest over to a tree, 130 feet total. About 20 random length radials in > the > > yard. The best I can do with a city lot. This antenna worked last year > > very well, but now I get this > > > > 12/1/2018 10:46:08 AM NOTES: > > > > Frequency SWR > > --------- --- > > 001800000 1.3 > > 001810000 1.4 > > 001820000 1.4 > > 001830000 1.4 > > 001840000 1.4 > > 001850000 1.5 > > 001860000 1.6 > > 001870000 1.6 > > 001880000 1.5 > > 001890000 1.5 > > 001900000 1.6 > > 001910000 1.6 > > 001920000 1.6 > > 001930000 1.6 > > 001940000 1.6 > > 001950000 1.6 > > 001960000 1.6 > > 001970000 1.7 > > 001980000 1.8 > > 001990000 2.0 > > 002000000 2.1 > > > > There seems to be NO resonance at all with this antenna. Before, I could > > operate the bottom of the band but nothing above 1850 without a tuner. I > > have changed out the coax feeding the antenna which hepl bring signals > up, > > but it seems to be a dummy load. > > > > Anyone have an idea what is going on? Shucks, I am out of ideas. Unless > > my ground plane has gone wonky > > > > My tuner can't find a match for it either. I have an automatice tuner > now, > > but it cannot find a match. Something is wrong here and I am stumped. > > > > Any help from the antenna gurus out there? > > > > Lee - K0WA > > ______________________________________________________________ > > Elecraft mailing list > > Home: http://mailman.qth.net/mailman/listinfo/elecraft > > Help: http://mailman.qth.net/mmfaq.htm > > Post: mailto:[hidden email] > > > > This list hosted by: http://www.qsl.net > > Please help support this email list: http://www.qsl.net/donate.html > > Message delivered to [hidden email] > > ______________________________________________________________ > Elecraft mailing list > Home: http://mailman.qth.net/mailman/listinfo/elecraft > Help: http://mailman.qth.net/mmfaq.htm > Post: mailto:[hidden email] > > This list hosted by: http://www.qsl.net > Please help support this email list: http://www.qsl.net/donate.html > Message delivered to [hidden email] Elecraft mailing list Home: http://mailman.qth.net/mailman/listinfo/elecraft Help: http://mailman.qth.net/mmfaq.htm Post: mailto:[hidden email] This list hosted by: http://www.qsl.net Please help support this email list: http://www.qsl.net/donate.html Message delivered to [hidden email] |
In reply to this post by Craig Smith-4
On 12/1/2018 9:05 AM, Craig Smith wrote:
> ou’re on the right track with changing the coax. You have some sort of resistive loss. Not necessarily. Did you get on the air during the contest? Did you work anyone? SWR is NOT an indicator of antenna performance. Yes, the antenna appears to be resonant below 1.8 MHz. An inverted L consists of two parts, both equally important -- the vertical with the horizontal top, and the counterpoise/radial system. I agree that the broad SWR suggests a problem with the counterpoise/radial system. 73, Jim K9YC ______________________________________________________________ Elecraft mailing list Home: http://mailman.qth.net/mailman/listinfo/elecraft Help: http://mailman.qth.net/mmfaq.htm Post: mailto:[hidden email] This list hosted by: http://www.qsl.net Please help support this email list: http://www.qsl.net/donate.html Message delivered to [hidden email] |
In reply to this post by Vic Rosenthal
Agree on both points. The resonant point appears to be well below 1.8 MHz and there is clearly a lot of loss in there somewhere. He says he changed out the coax so water in the coax seems less likely. The fact that the resonance has dropped is odd, since it implies more length instead of less like you'd get with a bad connection. I wonder if the end of the wire that is in the tree has lost it's insulation and there is actually contact to wet wood there. That would add both additional loading and loss. 73, Dave AB7E On 12/1/2018 10:04 AM, Vic Rosenthal wrote: > 1. The resonant point seems to be at 1.80 or below. > 2. The broad response indicates high loss somewhere. If you hadn’t said that you changed it, I would suspect water in the coax. > > Victor 4X6GP > >> On 1 Dec 2018, at 18:54, Leroy Buller <[hidden email]> wrote: >> >> There >> I tried to get on 160 with my Inverted L last night. 60 feet up and the >> rest over to a tree, 130 feet total. About 20 random length radials in the >> yard. The best I can do with a city lot. This antenna worked last year >> very well, but now I get this >> >> 12/1/2018 10:46:08 AM NOTES: >> >> Frequency SWR >> --------- --- >> 001800000 1.3 >> 001810000 1.4 >> 001820000 1.4 >> 001830000 1.4 >> 001840000 1.4 >> 001850000 1.5 >> 001860000 1.6 >> 001870000 1.6 >> 001880000 1.5 >> 001890000 1.5 >> 001900000 1.6 >> 001910000 1.6 >> 001920000 1.6 >> 001930000 1.6 >> 001940000 1.6 >> 001950000 1.6 >> 001960000 1.6 >> 001970000 1.7 >> 001980000 1.8 >> 001990000 2.0 >> 002000000 2.1 >> >> There seems to be NO resonance at all with this antenna. Before, I could >> operate the bottom of the band but nothing above 1850 without a tuner. I >> have changed out the coax feeding the antenna which hepl bring signals up, >> but it seems to be a dummy load. >> >> Anyone have an idea what is going on? Shucks, I am out of ideas. Unless >> my ground plane has gone wonky >> >> My tuner can't find a match for it either. I have an automatice tuner now, >> but it cannot find a match. Something is wrong here and I am stumped. >> >> Any help from the antenna gurus out there? >> >> Lee - K0WA >> ______________________________________________________________ >> Elecraft mailing list >> Home: http://mailman.qth.net/mailman/listinfo/elecraft >> Help: http://mailman.qth.net/mmfaq.htm >> Post: mailto:[hidden email] >> >> This list hosted by: http://www.qsl.net >> Please help support this email list: http://www.qsl.net/donate.html >> Message delivered to [hidden email] > ______________________________________________________________ > Elecraft mailing list > Home: http://mailman.qth.net/mailman/listinfo/elecraft > Help: http://mailman.qth.net/mmfaq.htm > Post: mailto:[hidden email] > > This list hosted by: http://www.qsl.net > Please help support this email list: http://www.qsl.net/donate.html > Message delivered to [hidden email] ______________________________________________________________ Elecraft mailing list Home: http://mailman.qth.net/mailman/listinfo/elecraft Help: http://mailman.qth.net/mmfaq.htm Post: mailto:[hidden email] This list hosted by: http://www.qsl.net Please help support this email list: http://www.qsl.net/donate.html Message delivered to [hidden email] |
That it dropped (from an unstated resonance), in simple terms would seem
to indicate (excluding radiator wire stretch or contact/induction with other objects) a change in the counterpoise. Some rot, rust, tiny livestock damage (moles) or other disconnect would be places to start looking. It could even be at the feed with bimetal reactions... failed CMC at the feed... some may not be visible (trust me on this one). Questions: was it a sudden, radical shift (something broke) or gradual (something rusted away)? Does it seem seasonal or temperature related (consistent is the best answer)? One more vote for measuring at the antenna feed, exclude the coax entirely. Rick nhc On 12/1/2018 12:39 PM, David Gilbert wrote: > > The fact that the resonance has dropped is odd, since it implies more > length instead of less like you'd get with a bad connection. I wonder > if the end of the wire that is in the tree has lost it's insulation > and there is actually contact to wet wood there. That would add both > additional loading and loss. > ______________________________________________________________ Elecraft mailing list Home: http://mailman.qth.net/mailman/listinfo/elecraft Help: http://mailman.qth.net/mmfaq.htm Post: mailto:[hidden email] This list hosted by: http://www.qsl.net Please help support this email list: http://www.qsl.net/donate.html Message delivered to [hidden email] |
In reply to this post by Leroy Buller
Lee,
Take an antenna analyzer out to the base of the antenna and measure between the radiator and the radial field. That should tell you what the antenna itself reads both for resonance and SWR. Then put a dummy load on the antenna end of the coax. Most antenna analyzers are capable of measuring the coax loss, so go into the shack at the other end of the coax and measure it. Those two steps will tell you whether the problem is with the antenna or the feedline. If you do not have a coax loss function on your antenna analyzer, feed the coax, put a wattmeter in the coax in the shack and observe the power. Without changing anything on the rig, remove the wattmeter and move it to the other end of the feedline. Have someone else do a TUNE on the rig while you observe the power at the other end of the coax - compare the two wattmeter readings. If nothing is revealed by those tests, look with close scrutiny at any coax connectors or adapters that you did not use for the tests - adapters are a frequent cause of failure - lesson to use only good ones. 73, Don W3FPR On 12/1/2018 11:54 AM, Leroy Buller wrote: > There > I tried to get on 160 with my Inverted L last night. 60 feet up and the > rest over to a tree, 130 feet total. About 20 random length radials in the > yard. The best I can do with a city lot. This antenna worked last year > very well, but now I get this > ______________________________________________________________ Elecraft mailing list Home: http://mailman.qth.net/mailman/listinfo/elecraft Help: http://mailman.qth.net/mmfaq.htm Post: mailto:[hidden email] This list hosted by: http://www.qsl.net Please help support this email list: http://www.qsl.net/donate.html Message delivered to [hidden email] |
In reply to this post by David Gilbert
How are you determining resonance?
If you are measuring strictly voltage standing wave ratio with for example, a Bird 43 meter, then a reactive system whose characteristic impedance is far from 50 Ω, may in fact show the lowest SWR meter reading at a point well off the actual antenna resonance. 73, Charlie k3ICH -----Original Message----- From: [hidden email] <[hidden email]> On Behalf Of David Gilbert Sent: Saturday, December 01, 2018 3:39 PM To: [hidden email] Subject: Re: [Elecraft] I am flummoxed about my antenna Agree on both points. The resonant point appears to be well below 1.8 MHz and there is clearly a lot of loss in there somewhere. He says he changed out the coax so water in the coax seems less likely. The fact that the resonance has dropped is odd, since it implies more length instead of less like you'd get with a bad connection. I wonder if the end of the wire that is in the tree has lost it's insulation and there is actually contact to wet wood there. That would add both additional loading and loss. 73, Dave AB7E On 12/1/2018 10:04 AM, Vic Rosenthal wrote: > 1. The resonant point seems to be at 1.80 or below. > 2. The broad response indicates high loss somewhere. If you hadn’t said that you changed it, I would suspect water in the coax. > > Victor 4X6GP > >> On 1 Dec 2018, at 18:54, Leroy Buller <[hidden email]> wrote: >> >> There >> I tried to get on 160 with my Inverted L last night. 60 feet up and the >> rest over to a tree, 130 feet total. About 20 random length radials in the >> yard. The best I can do with a city lot. This antenna worked last year >> very well, but now I get this >> >> 12/1/2018 10:46:08 AM NOTES: >> >> Frequency SWR >> --------- --- >> 001800000 1.3 >> 001810000 1.4 >> 001820000 1.4 >> 001830000 1.4 >> 001840000 1.4 >> 001850000 1.5 >> 001860000 1.6 >> 001870000 1.6 >> 001880000 1.5 >> 001890000 1.5 >> 001900000 1.6 >> 001910000 1.6 >> 001920000 1.6 >> 001930000 1.6 >> 001940000 1.6 >> 001950000 1.6 >> 001960000 1.6 >> 001970000 1.7 >> 001980000 1.8 >> 001990000 2.0 >> 002000000 2.1 >> >> There seems to be NO resonance at all with this antenna. Before, I could >> operate the bottom of the band but nothing above 1850 without a tuner. I >> have changed out the coax feeding the antenna which hepl bring signals up, >> but it seems to be a dummy load. >> >> Anyone have an idea what is going on? Shucks, I am out of ideas. Unless >> my ground plane has gone wonky >> >> My tuner can't find a match for it either. I have an automatice tuner now, >> but it cannot find a match. Something is wrong here and I am stumped. >> >> Any help from the antenna gurus out there? >> >> Lee - K0WA >> ______________________________________________________________ >> Elecraft mailing list >> Home: http://mailman.qth.net/mailman/listinfo/elecraft >> Help: http://mailman.qth.net/mmfaq.htm >> Post: mailto:[hidden email] >> >> This list hosted by: http://www.qsl.net >> Please help support this email list: http://www.qsl.net/donate.html >> Message delivered to [hidden email] > ______________________________________________________________ > Elecraft mailing list > Home: http://mailman.qth.net/mailman/listinfo/elecraft > Help: http://mailman.qth.net/mmfaq.htm > Post: mailto:[hidden email] > > This list hosted by: http://www.qsl.net > Please help support this email list: http://www.qsl.net/donate.html > Message delivered to [hidden email] ______________________________________________________________ Elecraft mailing list Home: http://mailman.qth.net/mailman/listinfo/elecraft Help: http://mailman.qth.net/mmfaq.htm Post: mailto:[hidden email] This list hosted by: http://www.qsl.net Please help support this email list: http://www.qsl.net/donate.html Message delivered to [hidden email] ______________________________________________________________ Elecraft mailing list Home: http://mailman.qth.net/mailman/listinfo/elecraft Help: http://mailman.qth.net/mmfaq.htm Post: mailto:[hidden email] This list hosted by: http://www.qsl.net Please help support this email list: http://www.qsl.net/donate.html Message delivered to [hidden email] |
In reply to this post by Vic Rosenthal
I think the counterpoise is wonky as many of you have stated.. I have
tested the antenna at the feed point at it is the same that I see in the shack. There is no resonance with this antenna. Yes, it is cut long too. When I did have it working it was 1.3 to 1 at 1835.. It is very wet and rainy here and I think the counterpoise is a mess. I have not done maintenance on it this year since I was in the hospital in July and recovering the last four months Yes, it was that way. So, next week, I am going to put up two elevated radials about 7 feet high and then take off the radials on the ground...or at least try to clean them up. But, the rain, wet and cold of Kansas has damped my enthusiasm for fixing it this weekend., RATS! I like the 160 contest. But it does seem the actual antenna is OK. The end of the 130 feet has a big insulator on it and it is about 6 foot from a tree limb. So, it is not touching the tree. Since I am retired....next week will be sufficient. Lee On Sat, Dec 1, 2018 at 11:04 AM Vic Rosenthal <[hidden email]> wrote: > 1. The resonant point seems to be at 1.80 or below. > 2. The broad response indicates high loss somewhere. If you hadn’t said > that you changed it, I would suspect water in the coax. > > Victor 4X6GP > > > On 1 Dec 2018, at 18:54, Leroy Buller <[hidden email]> wrote: > > > > There > > I tried to get on 160 with my Inverted L last night. 60 feet up and the > > rest over to a tree, 130 feet total. About 20 random length radials in > the > > yard. The best I can do with a city lot. This antenna worked last year > > very well, but now I get this > > > > 12/1/2018 10:46:08 AM NOTES: > > > > Frequency SWR > > --------- --- > > 001800000 1.3 > > 001810000 1.4 > > 001820000 1.4 > > 001830000 1.4 > > 001840000 1.4 > > 001850000 1.5 > > 001860000 1.6 > > 001870000 1.6 > > 001880000 1.5 > > 001890000 1.5 > > 001900000 1.6 > > 001910000 1.6 > > 001920000 1.6 > > 001930000 1.6 > > 001940000 1.6 > > 001950000 1.6 > > 001960000 1.6 > > 001970000 1.7 > > 001980000 1.8 > > 001990000 2.0 > > 002000000 2.1 > > > > There seems to be NO resonance at all with this antenna. Before, I could > > operate the bottom of the band but nothing above 1850 without a tuner. I > > have changed out the coax feeding the antenna which hepl bring signals > up, > > but it seems to be a dummy load. > > > > Anyone have an idea what is going on? Shucks, I am out of ideas. Unless > > my ground plane has gone wonky > > > > My tuner can't find a match for it either. I have an automatice tuner > now, > > but it cannot find a match. Something is wrong here and I am stumped. > > > > Any help from the antenna gurus out there? > > > > Lee - K0WA > > ______________________________________________________________ > > Elecraft mailing list > > Home: http://mailman.qth.net/mailman/listinfo/elecraft > > Help: http://mailman.qth.net/mmfaq.htm > > Post: mailto:[hidden email] > > > > This list hosted by: http://www.qsl.net > > Please help support this email list: http://www.qsl.net/donate.html > > Message delivered to [hidden email] > Elecraft mailing list Home: http://mailman.qth.net/mailman/listinfo/elecraft Help: http://mailman.qth.net/mmfaq.htm Post: mailto:[hidden email] This list hosted by: http://www.qsl.net Please help support this email list: http://www.qsl.net/donate.html Message delivered to [hidden email] |
In reply to this post by Charlie T, K3ICH
As you are dealing with an inverted L and the lengths you are using are
about 1/4 wave on 160M for the inverted L. You should have some inductance in series at the feed point to bring it close to resonance on 160M. Ground loss in the system will only add to radiation resistance and make the antenna appear more like a dummy load. Thus no indicated resonance. The better the ground system, the sharper the antenna or higher Q. 73 Bob, K4TAX ______________________________________________________________ Elecraft mailing list Home: http://mailman.qth.net/mailman/listinfo/elecraft Help: http://mailman.qth.net/mmfaq.htm Post: mailto:[hidden email] This list hosted by: http://www.qsl.net Please help support this email list: http://www.qsl.net/donate.html Message delivered to [hidden email] |
In reply to this post by Charlie T, K3ICH
I'm not "determining resonance" at all. I agree that lowest SWR doesn't correlate to resonance, but according to what he's given us so far the point of lowest SWR has shifted down with a MUCH broader curve. That indicates some kind of additional loading, in inductive and resistive. And in spite of what K3ICH says, such a change could have occurred just as likely in the vertical portion as in the radial portion. And I don't see how you get the idea his characteristic impedance is far from 50 ohms. Did you read his SWR curve? One way or another his net feedpoint impedance is pretty close to 50 ohms. We're not talking general theory here ... we're talking the numbers he has given us and won't have a better idea of anything until he gives us more information. I merely suggested some things he should check. Dave AB7E On 12/1/2018 2:38 PM, Charlie T wrote: > How are you determining resonance? > > If you are measuring strictly voltage standing wave ratio with for example, a Bird 43 meter, then a reactive system whose characteristic impedance is far from 50 Ω, may in fact show the lowest SWR meter reading at a point well off the actual antenna resonance. > > 73, Charlie k3ICH > > > > > -----Original Message----- > From: [hidden email] <[hidden email]> On Behalf Of David Gilbert > Sent: Saturday, December 01, 2018 3:39 PM > To: [hidden email] > Subject: Re: [Elecraft] I am flummoxed about my antenna > > > Agree on both points. The resonant point appears to be well below 1.8 MHz and there is clearly a lot of loss in there somewhere. He says he changed out the coax so water in the coax seems less likely. > > The fact that the resonance has dropped is odd, since it implies more length instead of less like you'd get with a bad connection. I wonder if the end of the wire that is in the tree has lost it's insulation and there is actually contact to wet wood there. That would add both additional loading and loss. > > 73, > Dave AB7E > > > > On 12/1/2018 10:04 AM, Vic Rosenthal wrote: >> 1. The resonant point seems to be at 1.80 or below. >> 2. The broad response indicates high loss somewhere. If you hadn’t said that you changed it, I would suspect water in the coax. >> >> Victor 4X6GP >> >>> On 1 Dec 2018, at 18:54, Leroy Buller <[hidden email]> wrote: >>> >>> There >>> I tried to get on 160 with my Inverted L last night. 60 feet up and the >>> rest over to a tree, 130 feet total. About 20 random length radials in the >>> yard. The best I can do with a city lot. This antenna worked last year >>> very well, but now I get this >>> >>> 12/1/2018 10:46:08 AM NOTES: >>> >>> Frequency SWR >>> --------- --- >>> 001800000 1.3 >>> 001810000 1.4 >>> 001820000 1.4 >>> 001830000 1.4 >>> 001840000 1.4 >>> 001850000 1.5 >>> 001860000 1.6 >>> 001870000 1.6 >>> 001880000 1.5 >>> 001890000 1.5 >>> 001900000 1.6 >>> 001910000 1.6 >>> 001920000 1.6 >>> 001930000 1.6 >>> 001940000 1.6 >>> 001950000 1.6 >>> 001960000 1.6 >>> 001970000 1.7 >>> 001980000 1.8 >>> 001990000 2.0 >>> 002000000 2.1 >>> >>> There seems to be NO resonance at all with this antenna. Before, I could >>> operate the bottom of the band but nothing above 1850 without a tuner. I >>> have changed out the coax feeding the antenna which hepl bring signals up, >>> but it seems to be a dummy load. >>> >>> Anyone have an idea what is going on? Shucks, I am out of ideas. Unless >>> my ground plane has gone wonky >>> >>> My tuner can't find a match for it either. I have an automatice tuner now, >>> but it cannot find a match. Something is wrong here and I am stumped. >>> >>> Any help from the antenna gurus out there? >>> >>> Lee - K0WA >>> ______________________________________________________________ >>> Elecraft mailing list >>> Home: http://mailman.qth.net/mailman/listinfo/elecraft >>> Help: http://mailman.qth.net/mmfaq.htm >>> Post: mailto:[hidden email] >>> >>> This list hosted by: http://www.qsl.net >>> Please help support this email list: http://www.qsl.net/donate.html >>> Message delivered to [hidden email] >> ______________________________________________________________ >> Elecraft mailing list >> Home: http://mailman.qth.net/mailman/listinfo/elecraft >> Help: http://mailman.qth.net/mmfaq.htm >> Post: mailto:[hidden email] >> >> This list hosted by: http://www.qsl.net >> Please help support this email list: http://www.qsl.net/donate.html >> Message delivered to [hidden email] > ______________________________________________________________ > Elecraft mailing list > Home: http://mailman.qth.net/mailman/listinfo/elecraft > Help: http://mailman.qth.net/mmfaq.htm > Post: mailto:[hidden email] > > This list hosted by: http://www.qsl.net > Please help support this email list: http://www.qsl.net/donate.html > Message delivered to [hidden email] > > ______________________________________________________________ > Elecraft mailing list > Home: http://mailman.qth.net/mailman/listinfo/elecraft > Help: http://mailman.qth.net/mmfaq.htm > Post: mailto:[hidden email] > > This list hosted by: http://www.qsl.net > Please help support this email list: http://www.qsl.net/donate.html > Message delivered to [hidden email] ______________________________________________________________ Elecraft mailing list Home: http://mailman.qth.net/mailman/listinfo/elecraft Help: http://mailman.qth.net/mmfaq.htm Post: mailto:[hidden email] This list hosted by: http://www.qsl.net Please help support this email list: http://www.qsl.net/donate.html Message delivered to [hidden email] |
In reply to this post by Bob McGraw - K4TAX
On 12/1/2018 6:34 PM, Bob McGraw K4TAX wrote:
> for the inverted L. Here's a tutorial applications note in the form of slides for a talk that I've given at ham conventions and club meetings. that is aimed at helping hams think about issues like this. Almost none of it is unique to me -- mostly I'm organizing a lot of serious work done by heavy hitters like N6LF, W8JI, K3LC, N7CL, NC0B (Rob Sherwood), and K2AV, and attempting to present the concepts in a manner that has a solid engineering basis and helps hams understand what's going on. It's mostly about radial/counterpoise systems. http://k9yc.com/160MPacificon.pdf 73, Jim K9YC ______________________________________________________________ Elecraft mailing list Home: http://mailman.qth.net/mailman/listinfo/elecraft Help: http://mailman.qth.net/mmfaq.htm Post: mailto:[hidden email] This list hosted by: http://www.qsl.net Please help support this email list: http://www.qsl.net/donate.html Message delivered to [hidden email] |
In reply to this post by Leroy Buller
I use an 1/8 wavelength top-loaded vertical up a tree with one 1/8 wavelength elevated radial. I had it tuned dead on at 1830 and it works quite well for what it is BUT with the rain the last several nights, the ground is wet, tree is wet, antenna is wet, the 1:1 SWR point moved down about 50 kHz ... turned on the tuner for the contest. Once things dry out at your QTH do another SWR check and see how things measure up.
73, Mike WA5POK (P S - I apologize to anyone hear that called and I didn't hear ... fought an S7 noise all weekend long. Ugh.) On Saturday, December 1, 2018 8:54 PM, Leroy Buller <[hidden email]> wrote: I think the counterpoise is wonky as many of you have stated.. I have tested the antenna at the feed point at it is the same that I see in the shack. There is no resonance with this antenna. Yes, it is cut long too. When I did have it working it was 1.3 to 1 at 1835.. It is very wet and rainy here and I think the counterpoise is a mess. I have not done maintenance on it this year since I was in the hospital in July and recovering the last four months Yes, it was that way. So, next week, I am going to put up two elevated radials about 7 feet high and then take off the radials on the ground...or at least try to clean them up. But, the rain, wet and cold of Kansas has damped my enthusiasm for fixing it this weekend., RATS! I like the 160 contest. But it does seem the actual antenna is OK. The end of the 130 feet has a big insulator on it and it is about 6 foot from a tree limb. So, it is not touching the tree. Since I am retired....next week will be sufficient. Lee On Sat, Dec 1, 2018 at 11:04 AM Vic Rosenthal <[hidden email]> wrote: > 1. The resonant point seems to be at 1.80 or below. > 2. The broad response indicates high loss somewhere. If you hadn’t said > that you changed it, I would suspect water in the coax. > > Victor 4X6GP > > > On 1 Dec 2018, at 18:54, Leroy Buller <[hidden email]> wrote: > > > > There > > I tried to get on 160 with my Inverted L last night. 60 feet up and the > > rest over to a tree, 130 feet total. About 20 random length radials in > the > > yard. The best I can do with a city lot. This antenna worked last year > > very well, but now I get this > > > > 12/1/2018 10:46:08 AM NOTES: > > > > Frequency SWR > > --------- --- > > 001800000 1.3 > > 001810000 1.4 > > 001820000 1.4 > > 001830000 1.4 > > 001840000 1.4 > > 001850000 1.5 > > 001860000 1.6 > > 001870000 1.6 > > 001880000 1.5 > > 001890000 1.5 > > 001900000 1.6 > > 001910000 1.6 > > 001920000 1.6 > > 001930000 1.6 > > 001940000 1.6 > > 001950000 1.6 > > 001960000 1.6 > > 001970000 1.7 > > 001980000 1.8 > > 001990000 2.0 > > 002000000 2.1 > > > > There seems to be NO resonance at all with this antenna. Before, I could > > operate the bottom of the band but nothing above 1850 without a tuner. I > > have changed out the coax feeding the antenna which hepl bring signals > up, > > but it seems to be a dummy load. > > > > Anyone have an idea what is going on? Shucks, I am out of ideas. Unless > > my ground plane has gone wonky > > > > My tuner can't find a match for it either. I have an automatice tuner > now, > > but it cannot find a match. Something is wrong here and I am stumped. > > > > Any help from the antenna gurus out there? > > > > Lee - K0WA > > ______________________________________________________________ > > Elecraft mailing list > > Home: http://mailman.qth.net/mailman/listinfo/elecraft > > Help: http://mailman.qth.net/mmfaq.htm > > Post: mailto:[hidden email] > > > > This list hosted by: http://www.qsl.net > > Please help support this email list: http://www.qsl.net/donate.html > > Message delivered to [hidden email] > Elecraft mailing list Home: http://mailman.qth.net/mailman/listinfo/elecraft Help: http://mailman.qth.net/mmfaq.htm Post: mailto:[hidden email] This list hosted by: http://www.qsl.net Please help support this email list: http://www.qsl.net/donate.html Message delivered to [hidden email] ______________________________________________________________ Elecraft mailing list Home: http://mailman.qth.net/mailman/listinfo/elecraft Help: http://mailman.qth.net/mmfaq.htm Post: mailto:[hidden email] This list hosted by: http://www.qsl.net Please help support this email list: http://www.qsl.net/donate.html Message delivered to [hidden email] |
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