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First Attempt
Hello all
I've made a first attempt at installing an antenna. It's a 2 Slinky dipole strung across my roof. I chose the Slinky dipole because it promised to give good (if not excellent) results in a relatively short antenna. I strung it between two 2' wood standards at the top of the roof. The roof is about 25-30' from the ground. I used the twin feedline, which is about 18', and the insulators from a GSRV Mini antenna I bought. The twinline is connected with a balun to a 50' RG-8X cable that runs across the roof and down to my window. I've temporarily led it in through the window. The excess cable, probably about 20 feet or so, is loosely coiled between the inner and outer window. The reception is great. I was picking up DX from Europe. However, I got no answers to any attempt to call out. I wasn't expecting DX for my very first QSO, but I was hoping for someone. I think it may be because the feedline runs along the roof rather than hanging in free space. Could this be the case? The SWR was terrible; it took my automatic tuner a lot of work to get a match, but I was getting 1.5 or less on 80 and 40. Thank you for any advice you can offer. 73 Basil Burgess, VE3JEB My email is basilb which is through hotmail |
First Attempt
Basil Burgess wrote:
Hello all I've made a first attempt at installing an antenna. It's a 2 Slinky dipole strung across my roof. I chose the Slinky dipole because it promised to give good (if not excellent) results in a relatively short antenna. I strung it between two 2' wood standards at the top of the roof. The roof is about 25-30' from the ground. I used the twin feedline, which is about 18', and the insulators from a GSRV Mini antenna I bought. The twinline is connected with a balun to a 50' RG-8X cable that runs across the roof and down to my window. I've temporarily led it in through the window. The excess cable, probably about 20 feet or so, is loosely coiled between the inner and outer window. I think it may be because the feedline runs along the roof rather than hanging in free space. Could this be the case? The SWR was terrible; it took my automatic tuner a lot of work to get a match, but I was getting 1.5 or less on 80 and 40. Actually, the entire antenna design is terrible. What is the SWR on the coax at the balun? Steel is not a good conductor to use in an antenna at RF frequencies. -- 73, Cecil http://www.qsl.net/w5dxp |
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Thank you for your response
I'm afraid I don't have a way of measuring the SWR at the coax. Should I consider connecting the balun directly to the slinkys rather than at the end of the twinline? Should the twinline be supported so that it is not lying on the roof? Or should I just dismantle it and go back to positioning the GSRV Mini. That, at least, is a copper dipole. Thanks again Basil, VE3JEB "Cecil Moore" wrote in message . com... Actually, the entire antenna design is terrible. What is the SWR on the coax at the balun? Steel is not a good conductor to use in an antenna at RF frequencies. -- 73, Cecil http://www.qsl.net/w5dxp |
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Basil Burgess wrote:
Or should I just dismantle it and go back to positioning the GSRV Mini. That, at least, is a copper dipole. I won't presume to tell you what you "should" do. There are too many unknowns in your system. You may need to spring for an antenna analyzer, like the MFJ-259B. If it were me, I would junk the slinky antenna. At least the half-sized G5RV is known to work relatively well on 40m, 20m, 10m, and 6m. -- 73, Cecil http://www.qsl.net/w5dxp |
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"Basil Burgess" wrote in message ... Thank you for your response I'm afraid I don't have a way of measuring the SWR at the coax. Should I consider connecting the balun directly to the slinkys rather than at the end of the twinline? Should the twinline be supported so that it is not lying on the roof? Or should I just dismantle it and go back to positioning the GSRV Mini. That, at least, is a copper dipole. As Cecil said , it is hard to tell you what to do with the limiated information you have given. Nothing simple beats the good old dipole antenna. Problem is it is mostly a one band antenna. I have up an off center fed antenna and it seems to work fair for all the harmonic bands. The swr is a bit high on the WARC bands. It is about 130 feet long with a 4:1 balun in the center and fed with rg-8x coax. Even with the antenna you have up you should be able to work something if the rig will load it. It may be that the internal tuner to the rig is not able to match the antenna and most of the power is not getting out of the rig. The inernal tuners are only good for about a 3:1 or less swr to the antenna on most rigs. Cecil mentioned an expensive MFJ device. It is probably way too much over kill for most hams. One of the least expensive SWR meters will tell you if the antenna is anywhere in the ball park and which way you need to trim the antenna if you take several readings across the band. |
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Thank you, Ralph
I'm sorry if I am giving inadequate information. Besides the basic description of the antenna, I'm not sure what else to offer. I doubt it took anyone long to realize that I am a novice and have as much info on antennas as one learns for the Canadian basic exam, and and can glean from a borrowed copy of the ARRL Antenna Book. The only additions I have are that on closer inspection, the balun is Van Gorden's (the manufacturer of the original antenna) Hi-Q Center Insulator. Also, I am using an external automatic tuner, a Z-11 Pro by LDG. It apparently tunes the antenna down to an SWR of 1.5, but doesn't have the means to give a more accurate figure. My FT-875 displays SWR, as a bar display, but when the tuner has done its job, the rig seems to display no SWR bars, which I take to mean the rig sees a 1:1 or close to it. Still, I guess that's no guarantee that the power is being used efficiently. Anyway, thanks again for your help 73 Basil Burgess, VE3JEB |
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The best, all round, all band, antenna is a high centre-fed dipole of
no particular length, fed with an open-wire feedline of no particular length or impedance, all the way to the shack, used with a choke-balun and an unbalanced tuner. It is good down to the frequency at which the dipole is about 1/3-wavelength long. Simplicity = efficiency. Once tried you will never return to anything else. ---- Reg. |
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Basil Burgess wrote:
It apparently tunes the antenna down to an SWR of 1.5, ... An antenna tuner doesn't change the SWR between the tuner and the antenna. If it's 100:1 before the tuner does its thing, it is still 100:1 after the tuner does its thing. The extra feedline losses are caused by that unchanging SWR. -- 73, Cecil http://www.qsl.net/w5dxp |
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On Sat, 18 Mar 2006 14:54:25 -0500, "Basil Burgess"
wrote: Thank you, Ralph I'm sorry if I am giving inadequate information. Besides the basic description of the antenna, I'm not sure what else to offer. I doubt it took anyone long to realize that I am a novice and have as much info on antennas as one learns for the Canadian basic exam, and and can glean from a borrowed copy of the ARRL Antenna Book. The only additions I have are that on closer inspection, the balun is Van Gorden's (the manufacturer of the original antenna) Hi-Q Center Insulator. Also, I am using an external automatic tuner, a Z-11 Pro by LDG. It apparently tunes the antenna down to an SWR of 1.5, but doesn't have the means to give a more accurate figure. My FT-875 displays SWR, as a bar display, but when the tuner has done its job, the rig seems to display no SWR bars, which I take to mean the rig sees a 1:1 or close to it. Still, I guess that's no guarantee that the power is being used efficiently. Anyway, thanks again for your help 73 Basil Burgess, VE3JEB For a first attempt, it sounds like you've built a complicated affair: slinkies, twinlead, balun, coax, tuner, etc. You might try the other extreme, simple. A dipole of two straight wires cut to frequency, and a length of coax to the rig. Make the antenna a little long, and use your rig's swr meter to adjust the length down to resonance. bob k5qwg |
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On Sat, 18 Mar 2006 10:21:27 -0500, "Basil Burgess"
wrote: Hello all I've made a first attempt at installing an antenna. It's a 2 Slinky dipole strung across my roof. I chose the Slinky dipole because it promised to give good (if not excellent) results in a relatively short antenna. I strung it There is nothing in your post to indicate how long or short your antenna is. Perhaps it is a well known design and I just haven't heard of it in my limited experience. You say how difficult the coax was to match with an ATU, that is a big hint that the coax is operating at high VSWR. You say the SWR was terrible, what does that mean, do you have the numbers? Coax operated at high VSWR for significant length is quite lossy. If the impedance presented to the tuner is extreme, you can expect excessive losses there too. The ambient noise on low HF bands is very high compared to the noise floor in your receiver. An antenna system could be seriously lossy, and yet still allow you to hear all signals above the noise (though at reduced S meter deflection). Beware of depending on a simplified receiver test to infer transmit performance. Owen -- |
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Cecil Moore wrote in news:cIZSf.57484$Jd.33257
@newssvr25.news.prodigy.net: Basil Burgess wrote: It apparently tunes the antenna down to an SWR of 1.5, ... An antenna tuner doesn't change the SWR between the tuner and the antenna. If it's 100:1 before the tuner does its thing, it is still 100:1 after the tuner does its thing. The extra feedline losses are caused by that unchanging SWR. Yep, though feedline losses are not usually so large as to preclude at least SOME QSO's on 80 and 40 unless that SWR is AT LEAST 50 (especially on 80m). Of course poor quality coax and twinlead that is touching metal can really increase those losses, even though they actually REDUCE the SWR that the tuner is seeing. A slinky is such a poor antenna to begin with (basically a coil of iron), it's probably best to just feed it in the center with good quality 450 ohm line (which you then dress properly all the way to the tuner's balanced output--if the tuner has one or a balun located AT the tuner if it doesn't). Next best would be to feed it with decent COAX like LMR400 or better. For example, my balcony whip gives an SWR of almost 6 on CW at 3652. I could lower this by adding a capacity rig at the stinger end of the hamstick, but I'm a bit too lazy to keep going out and taking it off and the thing is resonant on 3729 where our phone net meets. But it's still 88 percent as efficient as it is at resonance when tuned up on 3652 with my tuner, which can tune that SWR flat. (We won't talk about how inefficient an 8ft antenna actually is on these frequencies, but you get the point). And that's using RG8X (Belden 9258). Better coax would improve that some. If the slinky actually has an SWR of 100, then 450 ohm ladder line would introduce additional loss, due to SWR of 2.04 db per 100 feet. Moral of the story, when using inefficient antennas with weird impedances, then make sure you use good, low-loss feedline and keep it short as you can. -- Dave Oldridge+ ICQ 1800667 |
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Owen, you know as well as I do his SWR meter does not indicate SWR on
the feedline where it might matter. So some of your comments don't make much sense. ---- Reg. |
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Reg Edwards wrote:
Owen, you know as well as I do his SWR meter does not indicate SWR on the feedline where it might matter. So some of your comments don't make much sense. ---- Reg. Just my two cents worth For my first transmission aerial I made a three band trapped dipole of split figure 8 mains cable(80,40 and 20) and fed it with coax, and strung the centre about 25 foot in the air and falling to about 10 foot at the ends. This has enabled me to work Britain, Spain, Italy and the US with 40 odd watts SSB. SWR is not perfect and perhaps I should prune it a little. The hardest part was tuning the traps. I believe this design came from the arrl handbook. I know that its not perfect and perhaps I should refine it, but for a starter aerial I have found it very good. Having said that there are things about it I want to experiment with. One thing I have found invaluable is more experienced local hams who will help. There are people much more knowledgeable about antennas here than me, but I am very happy with my home-brew antenna. hth 73 Warren ZL3LC |
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Thank you all for your help. The consensus seems to be that the overall
antenna is ill-conceived. I will revert the design to the original antenna and work out how to rig it. Thanks again for the information and education. I guess when one of you hears me, you'll know I worked it all out :-) 73 to all Basil Burgess, VE3JEB |
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On Sat, 18 Mar 2006 20:45:38 +0000 (UTC), "Reg Edwards"
wrote: Owen, you know as well as I do his SWR meter does not indicate SWR on the feedline where it might matter. So some of your comments don't make much sense. Reg, If Basil measured the SWR at the ATU end of the RG8/X (either directly or effectively with the ATU in bypass configuration if that is possible), that would provide information that could be used to estimate whether losses in the RG8/X were reasonable, and if reasonable, how reasonable. The RG8/X is probably the highest risk of serious loss in the antenna system. For clarity, I am not at all interested in the VSWR indicated looking into the ATU unless the ATU is in the bypass configuration, in which case the measurement is a valid indicator of the VSWR on the RG8/X. The line loss of 50' of RG8/X at 3.6MHz with a source end VSWR of 8:1 is around 1dB, and probably quite acceptable. Beyond a source end VSWR of 20:1, losses increase quickly to infinite loss at source end VSWR around 28:1. If the indicated reflected *power* at the ATU end of the coax is less than about 80%, or VSWR less than about 20, coax loss is probably manageable. Owen -- |
First Attempt
Basil Burgess wrote:
Hello all I've made a first attempt at installing an antenna. It's a 2 Slinky dipole strung across my roof. I chose the Slinky dipole because it promised to give good (if not excellent) results in a relatively short antenna. I strung it between two 2' wood standards at the top of the roof. The roof is about 25-30' from the ground. I used the twin feedline, which is about 18', and the insulators from a GSRV Mini antenna I bought. The twinline is connected with a balun to a 50' RG-8X cable that runs across the roof and down to my window. I've temporarily led it in through the window. The excess cable, probably about 20 feet or so, is loosely coiled between the inner and outer window. The reception is great. I was picking up DX from Europe. However, I got no answers to any attempt to call out. I wasn't expecting DX for my very first QSO, but I was hoping for someone. I think it may be because the feedline runs along the roof rather than hanging in free space. Could this be the case? The SWR was terrible; it took my automatic tuner a lot of work to get a match, but I was getting 1.5 or less on 80 and 40. Thank you for any advice you can offer. 73 Basil Burgess, VE3JEB My email is basilb which is through hotmail There is more to contacting DX then trying different antennas. You say you are picking up DX from Europe so you obviously have a setup that receives reasonably. How efficient it is transmitting is a different issue. Can you make local contacts in Canada and the USA? I was just trying to contact CN2R in Morrocco on 80 meters. I could hear him fine but he doesn't seem to hear me. Well I am running 100 watts with a trap dipole. He probably can't hear me. He is also probably running a kilowatt and I know he has great antennas. Much of the DX you will hear may be running 10 times the power you are and that is why you hear them and they don't hear you. Don't worry about the antenna too much until you make local contacts and work your way out to greater distances. Also, you may have to call for a long time to get through the pileup calling the DX (which you may not hear). Try calling CQ DX yourself and see if anyone comes back. Pete W6OP |
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Owen Duffy wrote: On Sat, 18 Mar 2006 10:21:27 -0500, "Basil Burgess" I've made a first attempt at installing an antenna. It's a 2 Slinky dipole strung across my roof. I chose the Slinky dipole because it promised to give good (if not excellent) results in a relatively short antenna. I strung it There is nothing in your post to indicate how long or short your antenna is. Perhaps it is a well known design and I just haven't heard of it in my limited experience. Owen and Basil, The slinky dipole comes from the misplaced notion that packing a few hundred feet of wire in a ten or twenty foot area makes an antenna a few hundred feet long. They totally miss the point of why an antenna radiates and how the steel spiral affects the efficiency. There isn't any attempt to make the antenna resoant either! Overall it is a terrible system, unless you just happen through luck to use it where the antenna has a low-order resonance and current maximum at the feedpoint. You could probably trim the slinky and make it work on a few bands where it would be OK. If you have enough room, just put up a dipole. Watch out for these gimmick antennas. There isn't any magic bullet with antennas. 73 Tom |
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Hello
I'm sorry, though I tried to word that idea carefully, I left room for confusion. I wasn't trying to work DX, I only meant that the antenna received a clear signal from distant stations. I know that this is entirely due to the sensitivity and selectivity of my receiver, and does not reflect the ability to transmit to that distance. I had no expectation of getting out to the rest of the world. I'd have been happy to talk to someone 3 miles from me, for a first QSO. Thank you for your ideas, though. 73 Basil VE3JEB "pbourget" wrote in message ups.com... There is more to contacting DX then trying different antennas. You say you are picking up DX from Europe so you obviously have a setup that receives reasonably. How efficient it is transmitting is a different issue. Can you make local contacts in Canada and the USA? I was just trying to contact CN2R in Morrocco on 80 meters. I could hear him fine but he doesn't seem to hear me. Well I am running 100 watts with a trap dipole. He probably can't hear me. He is also probably running a kilowatt and I know he has great antennas. Much of the DX you will hear may be running 10 times the power you are and that is why you hear them and they don't hear you. Don't worry about the antenna too much until you make local contacts and work your way out to greater distances. Also, you may have to call for a long time to get through the pileup calling the DX (which you may not hear). Try calling CQ DX yourself and see if anyone comes back. Pete W6OP |
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Reg,
The type of antenna you describe is very useful and popular. However, your assertion is much too sweeping as a generalization. In no particular order, here are some caveats: 1. The qualifier "best" is largely meaningless, absent an agreed set of weighted criteria for "goodness." (How important is: size? weight? cost? visual profile? bandwidth? instant QSY? gain? pattern? low-band performance vs. high-band performance? power-handling capacity? need for tuner? etc., etc., etc.) 2. A good case can be made that choosing the "right" length is "better" than a random length, within this type. 3. An excellent case can be made that center-fed is NOT always the "best" option, within this type. 4. I'll let the fans of this antenna type chime in with why they prefer balanced tuners and/or tuned feeders to the use of an unbalanced tuner... if they want to. (I use more tailored antennas, and don't need a tuner of any kind, most of the time.) 73, Ed "Reg Edwards" wrote in message ... The best, all round, all band, antenna is a high centre-fed dipole of no particular length, fed with an open-wire feedline of no particular length or impedance, all the way to the shack, used with a choke-balun and an unbalanced tuner. It is good down to the frequency at which the dipole is about 1/3-wavelength long. Simplicity = efficiency. Once tried you will never return to anything else. ---- Reg. |
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Old Ed wrote:
Reg, The type of antenna you describe is very useful and popular. However, your assertion is much too sweeping as a generalization. In no particular order, here are some caveats: 1. The qualifier "best" is largely meaningless, absent an agreed set of weighted criteria for "goodness." (How important is: size? weight? cost? visual profile? bandwidth? instant QSY? gain? pattern? low-band performance vs. high-band performance? power-handling capacity? need for tuner? etc., etc., etc.) I'm always hesitant to use words like "best" for all the reasons you state, but I think that Reg qualified things pretty well. Within the qualifications of all band dipoles, the ladder-line fed general dipole is pretty darn hard to beat. I recommend them to any new hams that ask me for advice on antennas. My rationale is that most new hams these days buy rigs that are all-band, transistorized units.These units are also sensitive to mismatches between antenna and rig. Most new hams are not antenna gurus either. So here is an antenna that will allow them to get on the air without a lot of fussing. The only real measurement caveats are some lengths that you don't want to use. So we end up with an antenna that allows the newbie to get on the air, allows them to learn some stuff by twiddling knobs and such, then when they have a bit more experience, they can tackle that more "advanced antenna" with it's more exacting design, trimming , and measurements. 2. A good case can be made that choosing the "right" length is "better" than a random length, within this type. 3. An excellent case can be made that center-fed is NOT always the "best" option, within this type. 4. I'll let the fans of this antenna type chime in with why they prefer balanced tuners and/or tuned feeders to the use of an unbalanced tuner... if they want to. (I use more tailored antennas, and don't need a tuner of any kind, most of the time.) As I do now. I've really been smitten with my OCF dipole, fed with Coax, because in no small part, the feedpoint drops straight down to my shack. That coupled with an automatic tuner in my radio , allowing me to "plug and play. But I still strongly urge newcomers to put up one of those ladder line dipoles for the experience. They work okay, too! 8^) "Reg Edwards" wrote in message ... The best, all round, all band, antenna is a high centre-fed dipole of no particular length, fed with an open-wire feedline of no particular length or impedance, all the way to the shack, used with a choke-balun and an unbalanced tuner. It is good down to the frequency at which the dipole is about 1/3-wavelength long. Simplicity = efficiency. Once tried you will never return to anything else. ---- Reg. |
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Hi Michael,
Thank you for your comments! I'd be interested in trading experiences with you on the OCF topic, either here or direct. Did you make one or buy one? I have interleaved some other responses below... 73, Ed "Michael Coslo" wrote in message ... Old Ed wrote: Reg, The type of antenna you describe is very useful and popular. However, your assertion is much too sweeping as a generalization. In no particular order, here are some caveats: 1. The qualifier "best" is largely meaningless, absent an agreed set of weighted criteria for "goodness." (How important is: size? weight? cost? visual profile? bandwidth? instant QSY? gain? pattern? low-band performance vs. high-band performance? power-handling capacity? need for tuner? etc., etc., etc.) I'm always hesitant to use words like "best" for all the reasons you state, but I think that Reg qualified things pretty well. I think Reg's ONLY qualifiers were "all round, all band" (presumably meaning 80 thru 10). To me, that description falls well short of the mark, as "qualifiers." Within the qualifications of all band dipoles, the ladder-line fed general dipole is pretty darn hard to beat. I recommend them to any new hams that ask me for advice on antennas. You can make a good case for this proposition. But I'm a bit puzzled on how these qualify as A-1 newbie antennas. First, our newbie to learn how to coddle finicky ladder line, bring it into the shack, and make the transition to unbalanced feed. Then he/she needs a crash course on transmatches: 1. Balanced or unbalanced design? (If unbalanced, may not work well with this antenna; if balanced, may not work with future, coax-fed antennas.) 2. Low or high power? (If low, may need to upgrade later.) 3. Manual or automatic? (If automatic, how interface to rig?) 4. Which brand and model? (Might Fine Junk or $quality$?) 5. New or used? 6. How do you operate the transmatch? If our newbie wants some power-handling capability, and plans to buy it new, he/she will need an extra 500 to 700 USD and more space on the desk. Re Reg's reference to a choke balun: I've been looking for good quality, commercial choke baluns equipped with SO-239 inputs and outputs. So far, I haven't found any; and I haven't been quite motivated enough to make one. What should our newbie do to get one, if needed? My rationale is that most new hams these days buy rigs that are all-band, transistorized units.These units are also sensitive to mismatches between antenna and rig. Most new hams are not antenna gurus either. So here is an antenna that will allow them to get on the air without a lot of fussing. The only real measurement caveats are some lengths that you don't want to use. I can't quite see how slogging thru all the above is going to be easier for a newbie than buying a Buckmaster OCF or basic trap dipole, buying a ready-made coax jumper of the required length, and then doing plug- and-play with the (typical) rig's built-in auto-tuner. But it probably would be more educational. So we end up with an antenna that allows the newbie to get on the air, allows them to learn some stuff by twiddling knobs and such, then when they have a bit more experience, they can tackle that more "advanced antenna" with it's more exacting design, trimming , and measurements. I'm having a hard time figuring out what antenna type(s) would be "more advanced" than the random-length-doublet-with-outboard-ATU, and yet require more fiddling. But I will grant you this: IF someone decides from the get-go that they want a glitzy transmatch at their operating position--whether they need it or not--then the balanced-feeder doublet makes pretty good sense. This would be especially true if there wasn't enough space for something like a Buckmaster OCF, but there was enough space for (say) an 88' doublet. 2. A good case can be made that choosing the "right" length is "better" than a random length, within this type. 3. An excellent case can be made that center-fed is NOT always the "best" option, within this type. 4. I'll let the fans of this antenna type chime in with why they prefer balanced tuners and/or tuned feeders to the use of an unbalanced tuner... if they want to. (I use more tailored antennas, and don't need a tuner of any kind, most of the time.) As I do now. I've really been smitten with my OCF dipole, fed with Coax, because in no small part, the feedpoint drops straight down to my shack. That coupled with an automatic tuner in my radio , allowing me to "plug and play. But I still strongly urge newcomers to put up one of those ladder line dipoles for the experience. They work okay, too! 8^) "Reg Edwards" wrote in message ... The best, all round, all band, antenna is a high centre-fed dipole of no particular length, fed with an open-wire feedline of no particular length or impedance, all the way to the shack, used with a choke-balun and an unbalanced tuner. It is good down to the frequency at which the dipole is about 1/3-wavelength long. Simplicity = efficiency. Once tried you will never return to anything else. ---- Reg. |
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Old Ed wrote:
Hi Michael, Thank you for your comments! I'd be interested in trading experiences with you on the OCF topic, either here or direct. Did you make one or buy one? I made mine. The design is a combination of one of the antennas on the salsawaves site. (I don't have the URL handy, but if you google salsawaves it will get you there.) The other section of the design was with EZNEC demo. I have interleaved some other responses below... 73, Ed "Michael Coslo" wrote in message ... Old Ed wrote: Reg, The type of antenna you describe is very useful and popular. However, your assertion is much too sweeping as a generalization. In no particular order, here are some caveats: 1. The qualifier "best" is largely meaningless, absent an agreed set of weighted criteria for "goodness." (How important is: size? weight? cost? visual profile? bandwidth? instant QSY? gain? pattern? low-band performance vs. high-band performance? power-handling capacity? need for tuner? etc., etc., etc.) I'm always hesitant to use words like "best" for all the reasons you state, but I think that Reg qualified things pretty well. I think Reg's ONLY qualifiers were "all round, all band" (presumably meaning 80 thru 10). To me, that description falls well short of the mark, as "qualifiers." Within the qualifications of all band dipoles, the ladder-line fed general dipole is pretty darn hard to beat. I recommend them to any new hams that ask me for advice on antennas. You can make a good case for this proposition. But I'm a bit puzzled on how these qualify as A-1 newbie antennas. First, our newbie to learn how to coddle finicky ladder line, bring it into the shack, and make the transition to unbalanced feed. Then he/she needs a crash course on transmatches: 1. Balanced or unbalanced design? (If unbalanced, may not work well with this antenna; if balanced, may not work with future, coax-fed antennas.) 2. Low or high power? (If low, may need to upgrade later.) 3. Manual or automatic? (If automatic, how interface to rig?) 4. Which brand and model? (Might Fine Junk or $quality$?) 5. New or used? 6. How do you operate the transmatch? I've always suggested cutting teeth on low power, then working your way up. Mistakes are a lot less dangerous that way. In most cases, I suggest the MFJ approach. I have one that is now in a emergency backup. My thoughts on them are that they are certainly not the highest quality, but they work, and you can always get rid of one to start another ham on their way. If our newbie wants some power-handling capability, and plans to buy it new, he/she will need an extra 500 to 700 USD and more space on the desk. Re Reg's reference to a choke balun: I've been looking for good quality, commercial choke baluns equipped with SO-239 inputs and outputs. So far, I haven't found any; and I haven't been quite motivated enough to make one. What should our newbie do to get one, if needed? I've made all my baluns, 4:1 and choke, for my setup. But you raise a good point, as I'll note below. My rationale is that most new hams these days buy rigs that are all-band, transistorized units.These units are also sensitive to mismatches between antenna and rig. Most new hams are not antenna gurus either. So here is an antenna that will allow them to get on the air without a lot of fussing. The only real measurement caveats are some lengths that you don't want to use. I can't quite see how slogging thru all the above is going to be easier for a newbie than buying a Buckmaster OCF or basic trap dipole, buying a ready-made coax jumper of the required length, and then doing plug- and-play with the (typical) rig's built-in auto-tuner. But it probably would be more educational. Ah, Ed, you have exposed me being shortsighted! I'm a compulsive homebrewer, and I never considered buying a ready made antenna. The other approach might be quite different than mine, and yet just as valid. So we end up with an antenna that allows the newbie to get on the air, allows them to learn some stuff by twiddling knobs and such, then when they have a bit more experience, they can tackle that more "advanced antenna" with it's more exacting design, trimming , and measurements. I'm having a hard time figuring out what antenna type(s) would be "more advanced" than the random-length-doublet-with-outboard-ATU, and yet require more fiddling. If a person decides to make a trap or even more so a fan dipole, they will be doing a lot of cutting and trimming and measuring. I've always thought that for a newbie to get their feet wet, the less of that and the more on-air experience with adjustments the better. But I will grant you this: IF someone decides from the get-go that they want a glitzy transmatch at their operating position--whether they need it or not--then the balanced-feeder doublet makes pretty good sense. This would be especially true if there wasn't enough space for something like a Buckmaster OCF, but there was enough space for (say) an 88' doublet. I've made an 88" doublet for field day. It was a very good antenna on 20 and 40 meters, and so-so on 80.(still not too awful bad). I know someone is going to ask me to define "Very good". In this case, I received many unsolicited comments on good signal strength on 40 and 20, had no trouble getting through on first call. On 80 I had to work a good bit harder. It is good to get another perspective on this. - 73 de Mike KB3EIA - - 2. A good case can be made that choosing the "right" length is "better" than a random length, within this type. 3. An excellent case can be made that center-fed is NOT always the "best" option, within this type. 4. I'll let the fans of this antenna type chime in with why they prefer balanced tuners and/or tuned feeders to the use of an unbalanced tuner... if they want to. (I use more tailored antennas, and don't need a tuner of any kind, most of the time.) As I do now. I've really been smitten with my OCF dipole, fed with Coax, because in no small part, the feedpoint drops straight down to my shack. That coupled with an automatic tuner in my radio , allowing me to "plug and play. But I still strongly urge newcomers to put up one of those ladder line dipoles for the experience. They work okay, too! 8^) "Reg Edwards" wrote in message ... The best, all round, all band, antenna is a high centre-fed dipole of no particular length, fed with an open-wire feedline of no particular length or impedance, all the way to the shack, used with a choke-balun and an unbalanced tuner. It is good down to the frequency at which the dipole is about 1/3-wavelength long. Simplicity = efficiency. Once tried you will never return to anything else. ---- Reg. |
First Attempt
Hi Michael,
I tried Google search for salsawaves, and came up with a link to an OCF "Windom" antenna. But clicking on the link just led to a sort of highjack web page containing only ad links. 73, Ed "Michael Coslo" wrote in message ... Old Ed wrote: Hi Michael, Thank you for your comments! I'd be interested in trading experiences with you on the OCF topic, either here or direct. Did you make one or buy one? I made mine. The design is a combination of one of the antennas on the salsawaves site. (I don't have the URL handy, but if you google salsawaves it will get you there.) The other section of the design was with EZNEC demo. I have interleaved some other responses below... 73, Ed "Michael Coslo" wrote in message ... Old Ed wrote: Reg, The type of antenna you describe is very useful and popular. However, your assertion is much too sweeping as a generalization. In no particular order, here are some caveats: 1. The qualifier "best" is largely meaningless, absent an agreed set of weighted criteria for "goodness." (How important is: size? weight? cost? visual profile? bandwidth? instant QSY? gain? pattern? low-band performance vs. high-band performance? power-handling capacity? need for tuner? etc., etc., etc.) I'm always hesitant to use words like "best" for all the reasons you state, but I think that Reg qualified things pretty well. I think Reg's ONLY qualifiers were "all round, all band" (presumably meaning 80 thru 10). To me, that description falls well short of the mark, as "qualifiers." Within the qualifications of all band dipoles, the ladder-line fed general dipole is pretty darn hard to beat. I recommend them to any new hams that ask me for advice on antennas. You can make a good case for this proposition. But I'm a bit puzzled on how these qualify as A-1 newbie antennas. First, our newbie to learn how to coddle finicky ladder line, bring it into the shack, and make the transition to unbalanced feed. Then he/she needs a crash course on transmatches: 1. Balanced or unbalanced design? (If unbalanced, may not work well with this antenna; if balanced, may not work with future, coax-fed antennas.) 2. Low or high power? (If low, may need to upgrade later.) 3. Manual or automatic? (If automatic, how interface to rig?) 4. Which brand and model? (Might Fine Junk or $quality$?) 5. New or used? 6. How do you operate the transmatch? I've always suggested cutting teeth on low power, then working your way up. Mistakes are a lot less dangerous that way. In most cases, I suggest the MFJ approach. I have one that is now in a emergency backup. My thoughts on them are that they are certainly not the highest quality, but they work, and you can always get rid of one to start another ham on their way. If our newbie wants some power-handling capability, and plans to buy it new, he/she will need an extra 500 to 700 USD and more space on the desk. Re Reg's reference to a choke balun: I've been looking for good quality, commercial choke baluns equipped with SO-239 inputs and outputs. So far, I haven't found any; and I haven't been quite motivated enough to make one. What should our newbie do to get one, if needed? I've made all my baluns, 4:1 and choke, for my setup. But you raise a good point, as I'll note below. My rationale is that most new hams these days buy rigs that are all-band, transistorized units.These units are also sensitive to mismatches between antenna and rig. Most new hams are not antenna gurus either. So here is an antenna that will allow them to get on the air without a lot of fussing. The only real measurement caveats are some lengths that you don't want to use. I can't quite see how slogging thru all the above is going to be easier for a newbie than buying a Buckmaster OCF or basic trap dipole, buying a ready-made coax jumper of the required length, and then doing plug- and-play with the (typical) rig's built-in auto-tuner. But it probably would be more educational. Ah, Ed, you have exposed me being shortsighted! I'm a compulsive homebrewer, and I never considered buying a ready made antenna. The other approach might be quite different than mine, and yet just as valid. So we end up with an antenna that allows the newbie to get on the air, allows them to learn some stuff by twiddling knobs and such, then when they have a bit more experience, they can tackle that more "advanced antenna" with it's more exacting design, trimming , and measurements. I'm having a hard time figuring out what antenna type(s) would be "more advanced" than the random-length-doublet-with-outboard-ATU, and yet require more fiddling. If a person decides to make a trap or even more so a fan dipole, they will be doing a lot of cutting and trimming and measuring. I've always thought that for a newbie to get their feet wet, the less of that and the more on-air experience with adjustments the better. But I will grant you this: IF someone decides from the get-go that they want a glitzy transmatch at their operating position--whether they need it or not--then the balanced-feeder doublet makes pretty good sense. This would be especially true if there wasn't enough space for something like a Buckmaster OCF, but there was enough space for (say) an 88' doublet. I've made an 88" doublet for field day. It was a very good antenna on 20 and 40 meters, and so-so on 80.(still not too awful bad). I know someone is going to ask me to define "Very good". In this case, I received many unsolicited comments on good signal strength on 40 and 20, had no trouble getting through on first call. On 80 I had to work a good bit harder. It is good to get another perspective on this. - 73 de Mike KB3EIA - - 2. A good case can be made that choosing the "right" length is "better" than a random length, within this type. 3. An excellent case can be made that center-fed is NOT always the "best" option, within this type. 4. I'll let the fans of this antenna type chime in with why they prefer balanced tuners and/or tuned feeders to the use of an unbalanced tuner... if they want to. (I use more tailored antennas, and don't need a tuner of any kind, most of the time.) As I do now. I've really been smitten with my OCF dipole, fed with Coax, because in no small part, the feedpoint drops straight down to my shack. That coupled with an automatic tuner in my radio , allowing me to "plug and play. But I still strongly urge newcomers to put up one of those ladder line dipoles for the experience. They work okay, too! 8^) "Reg Edwards" wrote in message ... The best, all round, all band, antenna is a high centre-fed dipole of no particular length, fed with an open-wire feedline of no particular length or impedance, all the way to the shack, used with a choke-balun and an unbalanced tuner. It is good down to the frequency at which the dipole is about 1/3-wavelength long. Simplicity = efficiency. Once tried you will never return to anything else. ---- Reg. |
First Attempt
Old Ed wrote:
Hi Michael, I tried Google search for salsawaves, and came up with a link to an OCF "Windom" antenna. But clicking on the link just led to a sort of highjack web page containing only ad links. Try this link, Ed. http://www.stroobandt.com/antennas/windom/index.html - 73 de Mike KB3EIA - |
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