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Cecil Moore wrote in message ...
Brian Kelly wrote: A pair of caps mechanically coupled via an insulated shaft coupling but completely isolated electrically from each other should work. Yes, that's what I had in mind. Mine are side-by-side with a non-conducting fiber-chain connecting the shafts. Same with my two rotary coils. When I said "dual-ganged", I meant mechanically ganged, not electrically ganged. | |/ Coax center wire--------|/|--------feedline-------- /| | ganged variable caps to dipole | |/ Coax braid--------------|/|--------feedline-------- /| | OK , I got off on the wrong foot, this is more better. Tnx for the clarification. Now back to Autocad so that I can enshrine it for posterity . . There are a lot of nice inexpensive instrument-quality parts out there which make it quite easy to mechanically couple variable caps, rotary inductors and I guess even pots but I've never seen that done. I'm partial to the miniature timing belts and gears. IF they're not wire-reinforced belts. For this tuner job there are plenty of options available. I had a monster remotely controlled tuner in the back yard for years for my end-fed 135 inverted L. I used a pair of old WW2 Navy gun director synchros, one in the shack which I cranked with a turns counter and the other in the tuner cabinet to spin the big rotary inductor via a small timing belt, never missed a lick. w3rv |
(N2EY) wrote in message . com...
(Brian Kelly) wrote in message . com... Cecil Moore wrote in message ... The books give all sorts of figures for "open wire line". But many of them are for the classic lines made of #14 copper spaced 4 to 6 inches with ceramic spreaders every few feet. Brown poly TV twin lead with rectangular holes punched in it is a whole 'nother ball game. 'Specially at high SWRs and when it's wet. Which may not be a consideration in NTX but is a big consideration in EPA. (a) It's only Field Day (b) If ya just gotta have "the real thing" it's out there for cheap: http://www.w7fg.com/ant.htm It can be coiled into a big helix as long as the adjacent coils are a couple of feet apart. You can run an insulated rope to the antenna feedpoint and coil the ladder-line on the rope with the coils tiewrapped a couple of feet apart. That's slick. Until the rain falls or the wind blows It rains on thousands of G5RVs every day all over the world and . . ? or somebody walks into it in the dark. .. . welcome to Field Day antenna farms . . Biggest headache, though, is switching the various lengths for different bands. No feedline switching involved here. I was thinking more along the lines of sniping one of the orange barrels which are the Pennsylvania State Flower. They're quite readily available at construction sites along the PA Turnpike and slinky-wrapping feedline around one of those should do the job. Would solve the walking-into-it problem too. The orange barrels wuz a JOKE! The big question for any FD antenna is "how many QSOs"? All the simulations and Smith charts don't count for any points - QSOs do. Exactly. So ya get a bit more loss when it rains on a G5RV, who cares?? Lemmee cite a good recent example of why too many people fuss too much with dB. here dB. there details. I was watching ops at the N3RS multiop station during the ARRL CW DX contest in March. Late in the contest the guy in the 20M seat was knocking out contacts as a respectable rate. The xcvr was an FT-1000 and the amp was a big remote-controlled ACOM. After some considerable amount of time he finally noticed that the amp had faulted and swithed itself offline when he changed bands to get on 20M. He'd been running barefoot the whole time without realizing it. The problem was sorted out, the amp was reset and off he went again this time with full power. His rate did not change by any discernable amount even though his "losses" went down by what . . 12 dB? So no, I am not gonna get my knickers in a twist over the collection of incidental losses one runs into with FD antennas and tuners. As you imply there are far more telling factors which determine the effectiveness of any station. My personal best is 629 QSOs with one 100W rig, one op, one mode, three bands and two antennas. Coax fed trapper set up as inverted V for 80/40, quarter wave groundplane elevated 5 feet with 8 sloping radials for 20. Anybody here beat that on FD with only dipoles and verticals? OK, change of topic here, I'm game. Anybody out there have well over a hundred countries confirmed on both 80 and 40 by using just a single length of end-fed wire for the antenna? 73 de Jim, N2EY |
JGBOYLES wrote:
A G5RV type antenna in its many configurations ought to work as advertised. :-) Hope springs eternal from the human breast. :-) And as you have proved Cecil, it can be tweaked. It can be tweaked to perform well on any and all HF bands. Mine does. -- 73, Cecil, W5DXP -----= Posted via Newsfeeds.Com, Uncensored Usenet News =----- http://www.newsfeeds.com - The #1 Newsgroup Service in the World! -----== Over 100,000 Newsgroups - 19 Different Servers! =----- |
Brian Kelly wrote:
OK , I got off on the wrong foot, this is more better. Tnx for the clarification. Now back to Autocad so that I can enshrine it for posterity . . Don't bother with the caps. I was 180 degrees out of phase. Try dual 3-30 microhenry rotary coils instead ... sorry about that. -- 73, Cecil, W5DXP -----= Posted via Newsfeeds.Com, Uncensored Usenet News =----- http://www.newsfeeds.com - The #1 Newsgroup Service in the World! -----== Over 100,000 Newsgroups - 19 Different Servers! =----- |
Cecil Moore wrote in message ...
Cecil Moore wrote: N2EY wrote: Biggest headache, though, is switching the various lengths for different bands. No switching the various lengths on this one, Jim. Just a 110 ft dipole fed with about 110 ft of fixed length ladder-line with two series variable caps as the one knob tuner. Covers from 3.5 MHz to 4.0 MHz with an SWR less than 1.7:1 and no lossy coils needed. I apologize to everyone for a mental blunder I made with this proposed antenna. The reactances are capacitive, not inductive. It would have to be tuned with series inductors which defeats the propose of a low loss design. Nothing ventured, nothing gained. Back to the G5RV . . w3rv |
In case you missed it, this thread is
about improvements that can be made to the standard G5RV, something in which tens of thousands of hams might be interested. -- 73, Cecil, W5DXP That's odd, by the header I thought it was supposed to be about locating cheap coax. I think dev/null had it right, it is a ****ing contest... --- Outgoing mail is certified Virus Free. Checked by AVG anti-virus system (http://www.grisoft.com). Version: 6.0.648 / Virus Database: 415 - Release Date: 3/31/04 |
Cecil Moore wrote in message ...
Mark Keith wrote: I was so disgusted with the things after the 2nd FD, I refused to ever use one again. And I haven't. I bring my own wire and coax just to make sure I don't get stuck on one. And I wasn't the only one complaining either... I won't be suffering with a system efficiency in the mid 90's... It would be easy to try my G5RV modification. For 3.8 MHz, it is 25 ft of "450" ladder-line with a 1000 pf cap in parallel at the ladder-line/coax junction. I wish you would open your closed mind and try it sometime. I don't have much use for one, even if I wanted to. I'll never dump my dipoles to change to a G5RV. I'll never use an antenna system with a coax/choke/ladder line feed either. Sorry...But feel free, if you want to... I guess this is what led me to question your choice of the perfect FD antenna. 80m, being the band of real issue. A perfect FD antenna would allow one to change bands relatively quickly without sacrificing performance. My G5RV does that. The only bands I work at FD are 80 and 40 CW. I use parallel dipoles at right angles. My band change is instant. If for some reason I get a wild hair, and decide to try 20, I get on the beam. I never go any higher than that, because it's always night when I operate. I don't do anything in the daytime except set up my junk, and then lounge around and look useless for a while....:/ I then go home, and come back later in the night and operate when it's cooler. The 110 ft dipole that I came up with has an SWR of less than 1.7:1 over the entire 75-80m band. That sure beats the bandwidth of a resonant coax-fed dipole. Who cares if I don't move more than 100kc all night? I zig zag back and forth from 3500 to about 3600...7000 to about 7075 on 40.. That's not the old wives' tale. The old wives' tale is, "A G5RV is a terrible antenna that cannot be improved to near perfection." With minor modifications, a G5RV will compete favorably with any other HF dipole on any HF band. I guess your idea of "near perfection" is different than mine...I agree it can be improved quite a bit, but I'll reserve comment on the "near perfection" part... If I wanted a multi band dipole using only one element, I would use a 80m dipole, with insulators at each point, for each band. I then use jumpers to bypass whichever insulators I want for a certain band. I prefer that method to yours because the feed stays at 50 ohms appx, and the pattern is a normal dipole pattern on any band I use. To me, this is more "perfect" than your method, as it retains my preferred "50=50=50" policy. :) But it's all personal preference...Below would be a 80/40/20 version, which also works 15m on the 40 leg. I've used this method many times. o-----------------o----------o----------00----------o----------o---------------o But for what he originally wanted as far as covering two parts of 80m, with one antenna, I still would prefer paralleled dipoles, cut for each section of the band. I would run them at right angles like a turnstile. The SWR curve will look like a "W". Solves his problem, and is still ultra efficient with no caps to diddle, weird feedline combos' etc..Add 40m legs, also in parallel, and it's instant bandchange between both parts of 80, and also 40. Won't have to do a thing except dial the radio around...I think he said he's already got the high bands covered...To me, thats the "perfect" antenna for his problem, and what I would run in his case. But to each his own I guess... MK |
Paul wrote:
That's odd, by the header I thought it was supposed to be about locating cheap coax. I think dev/null had it right, it is a ****ing contest... Subjects drift and split into different threads. If you don't like this thread, don't read it. Simple as that. -- 73, Cecil, W5DXP -----= Posted via Newsfeeds.Com, Uncensored Usenet News =----- http://www.newsfeeds.com - The #1 Newsgroup Service in the World! -----== Over 100,000 Newsgroups - 19 Different Servers! =----- |
Mark Keith wrote:
But to each his own I guess... MK I prefer experimenting to operating. -- 73, Cecil, W5DXP -----= Posted via Newsfeeds.Com, Uncensored Usenet News =----- http://www.newsfeeds.com - The #1 Newsgroup Service in the World! -----== Over 100,000 Newsgroups - 19 Different Servers! =----- |
Cecil Moore wrote in message ...
Brian Kelly wrote: OK , I got off on the wrong foot, this is more better. Tnx for the clarification. Now back to Autocad so that I can enshrine it for posterity . . Don't bother with the caps. I was 180 degrees out of phase. Try dual 3-30 microhenry rotary coils instead ... sorry about that. Lets not throw the baby out with the washwater, this ain't over Cecil. In fact it opens up possibilities. Fact is that very few ops who get on 80/75 use anywhere near the entire 3.5-4.0 segement, it's a function of one's specific interests and reasons for using the band. In my own case I'm a basically a DXer thus my only real interest is in just the 3.50-3.55 and 3.70-3.85 Mhz slices of the band. And in being able to have a single, simple antenna which presents low feedpoint SWRs in those frequency ranges. Which rules out conventional dipoles and most of the rest of it's relatives. In the case of your 110 foot flattop with it's 110 foot feedline and for my specific purposes the "tuner" would be a pair of inline lo-loss fixed coils with taps which are selectable with a simple two pole two-position ceramic rotary switch. Or make it a three pole switch and be able to ground the antenna. Three taps yields three slices, etc. A tuner like that would be a whole bunch easier to build and use and would require much less mechanical claptrap than the original pair of variable caps scheme requires. However if using your 110 foot run of ladderline and coils configuration is a hassle but a 44 foot feedline would work Mr. Boyle's design can be used to get the same basic performance results with the caps. The thread has produdced a couple good approaches for practical solutions for an old problem and they both go into my keepers book. w3rv |
Brian Kelly wrote:
In the case of your 110 foot flattop with it's 110 foot feedline and for my specific purposes the "tuner" would be a pair of inline lo-loss fixed coils with taps which are selectable with a simple two pole two-position ceramic rotary switch. Or make it a three pole switch and be able to ground the antenna. Three taps yields three slices, etc. A tuner like that would be a whole bunch easier to build and use and would require much less mechanical claptrap than the original pair of variable caps scheme requires. It's essentially moving the loading coils from the antenna to the hamshack and, according to EZNEC, gives a 1.1:1 SWR from 3.6 to 4.0 MHz. SWR goes up to 1.5:1 on 3.5 MHz. However if using your 110 foot run of ladderline and coils configuration is a hassle but a 44 foot feedline would work Mr. Boyle's design can be used to get the same basic performance results with the caps. The thread has produdced a couple good approaches for practical solutions for an old problem and they both go into my keepers book. It will be interesting to apply Mr. Boyle's design to your particular two-segment problem. -- 73, Cecil, W5DXP -----= Posted via Newsfeeds.Com, Uncensored Usenet News =----- http://www.newsfeeds.com - The #1 Newsgroup Service in the World! -----== Over 100,000 Newsgroups - 19 Different Servers! =----- |
Cecil Moore wrote in message
... Subjects drift and split into different threads. If you don't like this thread, don't read it. Simple as that. -- 73, Cecil, W5DXP Geeez, Cecil, no need to get emotional about it... --- Outgoing mail is certified Virus Free. Checked by AVG anti-virus system (http://www.grisoft.com). Version: 6.0.648 / Virus Database: 415 - Release Date: 3/31/04 |
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Paul wrote:
Cecil Moore wrote: Subjects drift and split into different threads. If you don't like this thread, don't read it. Simple as that. Geeez, Cecil, no need to get emotional about it... No emotion there, Paul, just objective logic. It's like saying, "If you don't like broccoli, don't eat it. Simple as that." -- 73, Cecil, W5DXP -----= Posted via Newsfeeds.Com, Uncensored Usenet News =----- http://www.newsfeeds.com - The #1 Newsgroup Service in the World! -----== Over 100,000 Newsgroups - 19 Different Servers! =----- |
Brian Kelly wrote:
The jumper-to-bandswitch antenna would work IF one was (a) able to drop and hoist the antenna quickly and conveniently (b) was inclined to futz around in the dark to change bands. I can (a) release the pulley on either end of my antenna or just pull on the feedline to get at the jumper point. I have (b) a mercury vapor arc-type nightlight in the backyard 10 feet distance from the feedline. -- 73, Cecil, W5DXP -----= Posted via Newsfeeds.Com, Uncensored Usenet News =----- http://www.newsfeeds.com - The #1 Newsgroup Service in the World! -----== Over 100,000 Newsgroups - 19 Different Servers! =----- |
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Cecil Moore wrote in message ...
Mark Keith wrote: But to each his own I guess... MK I prefer experimenting to operating. -- 73, Cecil, W5DXP Oh, so do I. I like the antenna and rig setups, but I actually don't like the operating part of it. I pretty much just sat around last year, and let the rest of them have at it. I didn't do much as I felt unusually lazy for some reason. :/ One reason was they switched to a puter logging, keying, rig control, and all that mess, and I'd never used it before. Was clumsy as heck to me...I think I almost prefer doing it all manual...I've never liked contest type operating. To me , it's work. My idea of a better field day is sitting in a lounge chair on one of the hill country rivers, in front of a smoker, maybe sipping a cool one, "I only drink under the clinical supervision of a doctor", doing pretty much nothing at all....Maybe a casual redneck yik-yak qso every hour or so...:/ That fast contest type stuff gives me brain damage after a while. But it's hard for me to avoid being drafted, as I work CW fairly swiftly, and can rack up the points if I feel so inclined...Thats why I never work fone. It's not viable pointwise when I get half the points for fone, but work either about the same overall speed...But, I usually feel inclined to relax...A friend of mine who is also a CW op, N5XZ, he tears it up. Usually makes the most points every year I think. But he likes that type of operating more than I do. He'll stick in there a long time, where I'll usually flake out after 2-3 hours on a good year.. MK |
Cecil Moore wrote in message ...
Brian Kelly wrote: The jumper-to-bandswitch antenna would work IF one was (a) able to drop and hoist the antenna quickly and conveniently (b) was inclined to futz around in the dark to change bands. I can (a) release the pulley on either end of my antenna or just pull on the feedline to get at the jumper point. Ship me your back yard a few days before the last full weeklend in June freight collect and I'll ship it back immediately the following Monday. I have (b) a mercury vapor arc-type nightlight in the backyard 10 feet distance from the feedline. .. . . oughta make life on 160 really "interesting" . . -- 73, Cecil, W5DXP w3rv |
Cecil Moore wrote in message ...
Brian Kelly wrote: In the case of your 110 foot flattop with it's 110 foot feedline and for my specific purposes the "tuner" would be a pair of inline lo-loss fixed coils with taps which are selectable with a simple two pole two-position ceramic rotary switch. Or make it a three pole switch and be able to ground the antenna. Three taps yields three slices, etc. A tuner like that would be a whole bunch easier to build and use and would require much less mechanical claptrap than the original pair of variable caps scheme requires. It's essentially moving the loading coils from the antenna to the hamshack That's OK, High Q loading coils are not necessairily bad things at all. A couple decent-size airwound coils are *much* easier to come by in the shack than they are up in the air and out in the weather. Plus you can vary the L right in the shack. and, according to EZNEC, gives a 1.1:1 SWR from 3.6 to 4.0 MHz. SWR goes up to 1.5:1 on 3.5 MHz. I could definitely live with that. However if using your 110 foot run of ladderline and coils configuration is a hassle but a 44 foot feedline would work Mr. Boyle's design can be used to get the same basic performance results with the caps. The thread has produdced a couple good approaches for practical solutions for an old problem and they both go into my keepers book. It will be interesting to apply Mr. Boyle's design to your particular two-segment problem. I'm not far enough along my modeling learning curve to be able to model transmission lines yet but you're obviously right. Assuming some full system modeling of the Boyle Special for basic guidance, the availability of a 259B, another ceramic rotary switch and a pile of silver mica caps what are the downsides of using fixed caps vs. variable caps? w3rv |
Brian Kelly wrote:
... what are the downsides of using fixed caps vs. variable caps? They're not variable and cannot compensate for rain, etc. -- 73, Cecil, W5DXP -----= Posted via Newsfeeds.Com, Uncensored Usenet News =----- http://www.newsfeeds.com - The #1 Newsgroup Service in the World! -----== Over 100,000 Newsgroups - 19 Different Servers! =----- |
In article ,
(Brian Kelly) writes: (N2EY) wrote in message .com... (Brian Kelly) wrote in message .com... Cecil Moore wrote in message ... The books give all sorts of figures for "open wire line". But many of them are for the classic lines made of #14 copper spaced 4 to 6 inches with ceramic spreaders every few feet. Brown poly TV twin lead with rectangular holes punched in it is a whole 'nother ball game. 'Specially at high SWRs and when it's wet. Which may not be a consideration in NTX but is a big consideration in EPA. (a) It's only Field Day Go down that road a little more and you're in a certain park I know of... (b) If ya just gotta have "the real thing" it's out there for cheap: http://www.w7fg.com/ant.htm nice stuff! It can be coiled into a big helix as long as the adjacent coils are a couple of feet apart. You can run an insulated rope to the antenna feedpoint and coil the ladder-line on the rope with the coils tiewrapped a couple of feet apart. That's slick. Until the rain falls or the wind blows It rains on thousands of G5RVs every day all over the world and . . ? And the loss goes up. or somebody walks into it in the dark. . . welcome to Field Day antenna farms . . One fella I knew useta always have an RCA phono jack arrangement in the coax somewhere near the op table. Seemed odd until he told about the time somebody drove across the site at 2 AM and the coax got caught in the guy's bumper.... The big question for any FD antenna is "how many QSOs"? All the simulations and Smith charts don't count for any points - QSOs do. Exactly. So ya get a bit more loss when it rains on a G5RV, who cares?? Depends on whether it takes the rate down. Lemmee cite a good recent example of why too many people fuss too much with dB. here dB. there details. I was watching ops at the N3RS multiop station during the ARRL CW DX contest in March. Late in the contest the guy in the 20M seat was knocking out contacts as a respectable rate. The xcvr was an FT-1000 and the amp was a big remote-controlled ACOM. After some considerable amount of time he finally noticed that the amp had faulted and swithed itself offline when he changed bands to get on 20M. He'd been running barefoot the whole time without realizing it. The problem was sorted out, the amp was reset and off he went again this time with full power. His rate did not change by any discernable amount even though his "losses" went down by what . . 12 dB? OK, fine. On that band, in that contest, with that rig and op, the dBs didn't make much difference. You wanna tell that gang to run low power next year? How about QRP? btw, I saw the 'RS farm from the PA TPK last week, not many dB wasted there! So no, I am not gonna get my knickers in a twist over the collection of incidental losses one runs into with FD antennas and tuners. As you imply there are far more telling factors which determine the effectiveness of any station. Of course. My personal best is 629 QSOs with one 100W rig, one op, one mode, three bands and two antennas. Coax fed trapper set up as inverted V for 80/40, quarter wave groundplane elevated 5 feet with 8 sloping radials for 20. Anybody here beat that on FD with only dipoles and verticals? OK, change of topic here, I'm game. Anybody out there have well over a hundred countries confirmed on both 80 and 40 by using just a single length of end-fed wire for the antenna? W2QHH, for one...;-) Here's my main point in all this: Whenever antennas are discussed, you will often see descriptions such as "we did really well" or "outstanding performance" or some such. Particularly FD antennas. But what constitutes "outstanding performance" is usually not defined. For some folks, making 10-15 QSOs per hour on FD when the band is wide open is "outstanding performance". For others, making 2-3 times that rate under similar conditions isn't "outstanding performance". Patterns and simulations and SWR curves on websites are great stuff, but what really matters to me in terms of "outstanding antenna performance" on FD is how many QSOs you have in the log when it's all done. 73 de Jim, N2EY |
N2EY wrote:
Patterns and simulations and SWR curves on websites are great stuff, but what really matters to me in terms of "outstanding antenna performance" on FD is how many QSOs you have in the log when it's all done. Some of us regard outstanding performance as how many 807's have been put away. :-) -- 73, Cecil, W5DXP -----= Posted via Newsfeeds.Com, Uncensored Usenet News =----- http://www.newsfeeds.com - The #1 Newsgroup Service in the World! -----== Over 100,000 Newsgroups - 19 Different Servers! =----- |
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