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Hamstick dipole for 80m
Hamsticks and their clones are for US 75m (4MHz) and not directly tunable to
80m (3,5 MHz) I plan a Hamstick dipole for Digimodes and CW for say 3560 kHz. What is the best way to lower the resonance frequency Some type of capasitive loading at the end of base(coil) section or an inductance at center wich could maybe also function as impedance transformer? What is the feedpoint resistance of Hamstick dipole? Any ideas or experiences? 73 Jouko OH5RM |
Hamstick dipole for 80m
JN wrote:
Hamsticks and their clones are for US 75m (4MHz) and not directly tunable to 80m (3,5 MHz) I plan a Hamstick dipole for Digimodes and CW for say 3560 kHz. What is the best way to lower the resonance frequency Some type of capasitive loading at the end of base(coil) section or an inductance at center wich could maybe also function as impedance transformer? What is the feedpoint resistance of Hamstick dipole? Any ideas or experiences? A hamstick has measured 12 dB down from a screwdriver during 75m mobile CA antenna shootouts. That screwdriver was about 10 dB down from a 1/2WL dipole. A 75m hamstick is little better than a dummy load having a radiation resistance of maybe 0.5 ohm and an efficiency in the ballpark of 1%, i.e. 100 watts in, 1 watt out. That said, the best way to accomplish what you are trying to do is to use extenders on the bottom sections. The longer the section underneath the coil, the greater the radiation efficiency. I have extenders in 1, 2, 3, 4, 5, and 6 foot lengths. They really come in handy for antenna experiments. If you could use 6 foot base extenders, that would make the dipole 8+6+6+8 = ~28 feet long overall. Assuming you could get that antenna up at a decent height (50+ feet), I think the performance might be "not bad". -- 73, Cecil http://www.w5dxp.com |
Hamstick dipole for 80m
"JN" wrote in
: Hamsticks and their clones are for US 75m (4MHz) and not directly tunable to 80m (3,5 MHz) I plan a Hamstick dipole for Digimodes and CW for say 3560 kHz. What is the best way to lower the resonance frequency Some type of capasitive loading at the end of base(coil) section or an inductance at center wich could maybe also function as impedance transformer? What is the feedpoint resistance of Hamstick dipole? Any ideas or experiences? 73 Jouko OH5RM Hi Jouko: I ran a “ham stick” dipole for a while and was able to compare it to a full size dipole when I put one up. To compare the two antennas, a “ham stick” dipole at 25’ verses a full size dipole at 35’. On 80/75m the “ham stick” was down about 20db from the dipole. The 2:1 SWR bandwidth was about 65KHz for the “ham stick” verses about 200+Khz for the dipole. The way to get a “ham stick” down the bottom of 80m is to lengthen the whip that sticks out the top. I can’t remember how much but it was not much. The Z of a whip of the length of a “ham stick” should be only a few ohms, but they are close to 50 Ohms when used as a dipole. The difference between 50 Ohms and the modeled 2 to 3 Ohms is the loss in the coils. The long, small diameter coils made with small gage wire cause most of the loss. The “ham stick” dipole is better than no antenna but not by much on 80m. As you go up in frequency the performance of dipoles made out mobile antennas improve. On 40m my “ham stick” dipole was 12db down from a full size dipole and on 20m and above it was less than an S-unit down. Note that I’m talking about dipoles made out “ham sticks” made for the respective bands, not using a tuner. Using a turner is a waste of time as you move farther away from the center frequency the loss goes way up and your signal goes away! I still use my 80m “ham sticks” but not as dipole. I have them ground mounted with 4 10’ radials each, spaced 1/16 wavelength apart and feed 90 deg. out of phase. This makes a directional receive antenna for the DX window on 80m that rivals a beverage antenna. It makes DXing on 80m fun. The only disadvantage is that unlike a beverage it only works over about a 65Khz chunk of the band. John Passaneau, W3JXP |
Hamstick dipole for 80m
On Tue, 25 Mar 2008 14:05:13 +0200, "JN" wrote:
Hamsticks and their clones are for US 75m (4MHz) and not directly tunable to 80m (3,5 MHz) I plan a Hamstick dipole for Digimodes and CW for say 3560 kHz. What is the best way to lower the resonance frequency Some type of capasitive loading at the end of base(coil) section or an inductance at center wich could maybe also function as impedance transformer? What is the feedpoint resistance of Hamstick dipole? Any ideas or experiences? 73 Jouko OH5RM The ham stick dipole isn't very great for 80 meters. I know from experience that the hustler mobile antenna works better than the ham stick on 75 meters. I have used the ham stick on 80 meters mobile with an antenna tuner. The antenna tuner gave me a much broader bandwidth as far as SWR is concerned without having to retune. On the other hand, you are not operating mobile. I don't know how this compares. I know when I did it, it gave me a very weak, but readable signal. I had a ground rod in the ground below my window. I connected the shield side of my coax to the ground stake and the center to one end of a long spool of wire. I stretched the wire out about 1/4 wave on the ground and checked the SWR. It was flat on the frequency I wanted (I got lucky) so I checked into the then GA SSB Net on 3975. I was weak, but readable and could pass my traffic. If you can make loading coils, make a couple with large diameters. The larger the better. Center load each element and make them so you can tap to the coil. This will work better than the ham stick. You may find that tapping at two different points works better for you so you have a bit of an offset in the electrical lengths of the antennas on either side of the coax. This is because the impedance of a shortened dipole antenna is lower than 50 ohms. The offset finds a better match. Hope this helps. Buck N4PGW -- 73 for now Buck, N4PGW www.lumpuckeroo.com "Small - broadband - efficient: pick any two." |
Hamstick dipole for 80m
Thanks for everybody for good comments,
They are quite in balance with the information I have red from net. The antenna which I am planning is for portable use and should be easy to erect and transport. Your remarks led me to some comments: - Yes the efficiency on 80m may be too low, because of small size. - Adding center extenders could help but then 75m hamsticks are out of 80m band - By using 40m hamsticks and maybe center loading coil and extenders tuning to 80m possible? - Then also operating on 40m without extenders OK - 80 operation only needed for domestic qsos, no DX - On 30m and 20m hamstick dipole would work OK Any comments on these? 73 Jouko OH5RM |
Hamstick dipole for 80m
If you could use 6 foot base extenders, that would make the dipole 8+6+6+8 = ~28 feet long overall. Assuming you could get that antenna up at a decent height (50+ feet), I think the performance might be "not bad". Cecil, I would be interested in finding out what you are using for base extenders..... varying lengths of ? with 3/8"-24 female one end, male another. You make something, or is something commercially available? Ed K7AAT |
Hamstick dipole for 80m
Jouko,
I had the same problem, despite assurances from the wholesaler in the USA where I bought the the two Hamsticks, they were resonant at their lowest at 3750 kHz. I needed to operate them at a lower frequency of no more than 3650 kHz I tried extending the stainless steel "stinger" but I couldn't find anything long enough. Then I tried a disk of aluminium 1.6mm x 75 mm in diameter, fitted between the stainless whip and the antenna proper, and that reduced the resonanant frequency to 3575 kHz, adjusting the stinger length was necessary of course. You may have to make the diameter of the disk slightly larger to get it to resonate at the lower frequency, just a matter of cut and try. Using my MFJ Analyser, the feedpoint resistance was close to 50 ohms. It was a very simple fix! 73 John VK2KCE "JN" wrote in message ... Hamsticks and their clones are for US 75m (4MHz) and not directly tunable to 80m (3,5 MHz) I plan a Hamstick dipole for Digimodes and CW for say 3560 kHz. What is the best way to lower the resonance frequency Some type of capasitive loading at the end of base(coil) section or an inductance at center wich could maybe also function as impedance transformer? What is the feedpoint resistance of Hamstick dipole? Any ideas or experiences? 73 Jouko OH5RM |
Hamstick dipole for 80m
- Yes the efficiency on 80m may be too low, because of small size. - Adding center extenders could help but then 75m hamsticks are out of 80m band - By using 40m hamsticks and maybe center loading coil and extenders tuning to 80m possible? - Then also operating on 40m without extenders OK - 80 operation only needed for domestic qsos, no DX - On 30m and 20m hamstick dipole would work OK Any comments on these? 73 Jouko OH5RM Ok, the antenna is portable. Toss a wire over a couple of tree limbs and either use full-sized 80 meter dipole, or load it with loading coils. If you load the antenna with coils located at the end point of 40 meters, you may find yourself with a dual band antenna -- 40/80. Since you are operating primarily local 80 meter operation, any height above ground up to about 20 feet will result in NVIS, pretty good signal there. You could also try a tree-limb somewhat vertical. Drop a short ground rod into the ground, tap shield to that and toss other end of 65 foot wire (plus or minus) over a tree limb. It will operate, but not perfect. However, it should work as well or better than the hamsticks. Just another thot Buck -- 73 for now Buck, N4PGW www.lumpuckeroo.com "Small - broadband - efficient: pick any two." |
Hamstick dipole for 80m
John,
Yes I think using capasitive loading at the end of coil parts is the right way to move the frequency. What kind of results did you get with the hamstick dipole? OK 50Ohm feedpoint resistance. I thought it is lower, but maybe it is so due to high loss resistance in coils. 73 Jouko OH5RM |
Hamstick dipole for 80m
JN wrote:
- Adding center extenders could help but then 75m hamsticks are out of 80m band ... Any comments on these? This is not necessarily true. Since the length of the top stinger has a much greater effect on resonant frequency than the length of the bottom section, you can increase that bottom section length by a large amount and then adjust the top stinger length by a smaller amount to achieve the desired resonant frequency. And you are going down in frequency to the CW portion of 80m. For instance, you might extend the bottom portion by 6 feet and only have to shorten the top stinger by 2 feet. (When you shorten the stinger, you may have to hacksaw off a portion to keep the stinger bottom from residing in the middle of the loading coil.) Let's say you have an eight foot long base-loaded mobile antenna. You decide to move the loading coil farther up the antenna to the center-loaded position. If you keep the *same length and same coil*, the resonant frequency will increase. You have to add more stinger length to bring it back to the original resonant frequency (or more coil). Moving the fixed coil farther away from the feedpoint requires the antenna length to be increased. That fact works in your favor. Since the additional bottom section is moving the fixed loading coil farther away from the feedpoint, the above effect will occur for your extended configuration. Experiment with it and see what happens. You could just use wire for the experimentation and hang it between two supports. -----/////-----+-----FP-----+-----/////----- hamstick wire wire hamstick -- 73, Cecil http://www.w5dxp.com |
Hamstick dipole for 80m
Ed_G wrote:
Cecil, I would be interested in finding out what you are using for base extenders..... varying lengths of ? with 3/8"-24 female one end, male another. You make something, or is something commercially available? Hustler makes various extender sections. I have 2 foot and 5 foot sections from Hustler. Most of my extender sections are from Henry, the Texas Bugcatcher guy. They are the "BASE MAST" sections available in lengths from 1/2 foot to 5 feet and special lengths can be ordered. http://www.texasbugcatcher.com/ -- 73, Cecil http://www.w5dxp.com |
Hamstick dipole for 80m
"Cecil Moore" Experiment with it and see what happens. You could just use wire for the experimentation and hang it between two supports. -----/////-----+-----FP-----+-----/////----- hamstick wire wire hamstick -- 73, Cecil http://www.w5dxp.com I have no hamsticks yet, but maybe I could use some simulation like this: http://www.k7mem.150m.com/Electronic.../shortant.html 73 Jouko OH5RM |
Hamstick dipole for 80m
JN wrote:
"Cecil Moore" Experiment with it and see what happens. You could just use wire for the experimentation and hang it between two supports. -----/////-----+-----FP-----+-----/////----- hamstick wire wire hamstick -- 73, Cecil http://www.w5dxp.com I have no hamsticks yet, but maybe I could use some simulation like this: http://www.k7mem.150m.com/Electronic.../shortant.html If you use a fiberglass rod for the coil form similar to the hamstick fiberglass rod and wind the same number of turns of the same size wire on it, it should work. But if you are going to go to that trouble, you might as well wind high-Q coils. In fact, if you replace the 75m hamstick coils with large-diameter high-Q coils, you can probably increase your radiated power by 1000%, i.e. 10 dB :-). -- 73, Cecil http://www.w5dxp.com |
Hamstick dipole for 80m
Most of my extender sections are from Henry, the Texas Bugcatcher guy. They are the "BASE MAST" sections available in lengths from 1/2 foot to 5 feet and special lengths can be ordered. http://www.texasbugcatcher.com/ Thanks. Looked it up.... nice selection. I'll be looking into this. Ed |
Hamstick dipole for 80m
On Mar 26, 8:16 am, Cecil Moore wrote:
Hustler makes various extender sections. I have 2 foot and 5 foot sections from Hustler. Most of my extender sections are from Henry, the Texas Bugcatcher guy. They are the "BASE MAST" sections available in lengths from 1/2 foot to 5 feet and special lengths can be ordered. I have a hustler 3 footer I use all the time.. Really cranks the performance up when you are parked and can use a taller whip. My normal whip is 11 ft, exactly center loaded, and the mast makes it 14, with the coil at 8 ft. I wish I had a 5 foot version. Might have to get one of those for industrial strength use. :/ Of course, if I had another 5 ft mast, I'd end up coupling them together and having 8 ft. :) There is no such thing as overkill with a stationary mobile setup. lol An 8 ft mast would give me a total height of 19 ft, and the coil would be at 13 ft. That would brown the food on 75/40 m... :- |
Hamstick dipole for 80m
I made an interesting simulation for the ham stick dipole.
I first took total lenght 16 FT (2x hamstick), at 4MHz loading coils near feedpoint calculated to be abt. 60 mikroH Then I took total lenght 28 FT (8+6/FP/6+8) coils then moved to almost center of elements. at 4MHz calculated 56 mikroH and the same configuration at 3.56 MHz calculated 71MikroH for each coil. Now 75m hamsicks seem to have abt. 60mikroH coils. If you use 2x6Ft extenders at center you need 71 mikroH to resonate at 3.56Mhz. This simulation uses ¨lumped coils not helical like in hamstick, but I think it is possible to use 75m sticks with extenders and still you need to lower the resonance for 80m CW use. 73 Jouko OH5RM "JN" wrote in message ... "Cecil Moore" Experiment with it and see what happens. You could just use wire for the experimentation and hang it between two supports. -----/////-----+-----FP-----+-----/////----- hamstick wire wire hamstick -- 73, Cecil http://www.w5dxp.com I have no hamsticks yet, but maybe I could use some simulation like this: http://www.k7mem.150m.com/Electronic.../shortant.html 73 Jouko OH5RM |
Hamstick dipole for 80m
JN wrote:
Now 75m hamsicks seem to have abt. 60mikroH coils. If you use 2x6Ft extenders at center you need 71 mikroH to resonate at 3.56Mhz. Which gives you incentive to replace the hamstick coils with relatively high-Q coils and thus increase your radiation efficiency by magnitudes. -- 73, Cecil http://www.w5dxp.com |
Hamstick dipole for 80m
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Hamstick dipole for 80m
On Mar 27, 7:54 am, Michael Coslo wrote:
How do you adjust the coil at that height? Of course I find that I choose and spend most of my time on one band per mobile session, so maybe it isn't a big problem. - 73 de Mike N3LI - Well, I only have a few taps on the coil, so I don't have to change all that often. I might have three taps for 80m, a couple for 40m, one each for the rest of the bands.. I'll tune the antenna in the normal 11 ft mode, using the usual tap for the freq I'm using, and then I add the 3 ft mast. I'll stay on the same coil tap, but shorten the stinger a couple of inches or so. I'm on 80 or 40 most all the time, so I don't have to change but maybe twice a day.. 40 all day, and then I'll switch to 75 at night when it gets dark. |
Hamstick dipole for 80m
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Hamstick dipole for 80m
Cecil Moore wrote:
wrote: ... I'll switch to 75 at night when it gets dark. What do you switch to at night when it doesn't get dark? :-) Dammit Cecil - not when I'm drinking coffee! hehehe 8^) - 73 de Mike N3LI - |
Hamstick dipole for 80m
On Mar 27, 11:29 am, Cecil Moore wrote:
wrote: ... I'll switch to 75 at night when it gets dark. What do you switch to at night when it doesn't get dark? :-) -- 73, Cecil http://www.w5dxp.com My map of Alaska. :/ |
Hamstick dipole for 80m
Hi Jouko,
I made up a 4 band "spider" mount, to which you can screw in 4 sets of hamsticks. I have a full set of hamstick whips from 80m down to 6m. So I have a multiband hamstick dipole array! When one thinks about the feedpoint impedance, even without the capacitive disk, it certainly should be lower, but as I am using them at 7 metres from groundlevel in a portable situation, I use a small antenna tuner. At that height, they act like a "cloud warmer" or a NVIS antenna, so at 80m its good for up to 350km. I haven't really given the other frequencies a try yet. Let me know I can email you with a few pics of my multiband "spider mount", as I have a small lathe and milling machine in my workshop, it wasn't hard to make. 73 de VK2KCE John "JN" wrote in message ... John, Yes I think using capasitive loading at the end of coil parts is the right way to move the frequency. What kind of results did you get with the hamstick dipole? OK 50Ohm feedpoint resistance. I thought it is lower, but maybe it is so due to high loss resistance in coils. 73 Jouko OH5RM |
Hamstick dipole for 80m
Michael Coslo wrote:
nm5k wrote: Cecil Moore wrote: Hustler makes various extender sections. I have 2 foot and 5 foot sections from Hustler. Most of my extender sections are from Henry, the Texas Bugcatcher guy. They are the "BASE MAST" sections available in lengths from 1/2 foot to 5 feet and special lengths can be ordered. I have a hustler 3 footer I use all the time.. Really cranks the performance up when you are parked and can use a taller whip. My normal whip is 11 ft, exactly center loaded, and the mast makes it 14, with the coil at 8 ft. I wish I had a 5 foot version. Might have to get one of those for industrial strength use. :/ Of course, if I had another 5 ft mast, I'd end up coupling them together and having 8 ft. :) There is no such thing as overkill with a stationary mobile setup. lol An 8 ft mast would give me a total height of 19 ft, and the coil would be at 13 ft. That would brown the food on 75/40 m... :- How do you adjust the coil at that height? Of course I find that I choose and spend most of my time on one band per mobile session, so maybe it isn't a big problem. - 73 de Mike N3LI - The Hustler MO-1 and MO-2 masts have a hinge at 15" and 27" above the bottom end: http://www.new-tronics.com/main/html/mobile__hf.html They're 54" tall. The MO-3 is also 54" tall but doesn't have the hinge. The MO-4 is 22" tall (no hinge). 73, Bryan WA7PRC |
Hamstick dipole for 80m
Cecil Moore writes:
wrote: ... I'll switch to 75 at night when it gets dark. What do you switch to at night when it doesn't get dark? :-) Why the smiley? "When I told you to turn off the light at 10:30PM, you were also supposed to stop reading, dear" Greetings from 63N. We don't get midnight sun, but we can read a newspaper all night long. 73 LA4RT Jon |
Hamstick dipole for 80m
Jon Kåre Hellan wrote:
"When I told you to turn off the light at 10:30PM, you were also supposed to stop reading, dear" :-) Do y'all call that night or day? -- 73, Cecil http://www.w5dxp.com |
Hamstick dipole for 80m
Cecil Moore writes:
Jon KÃ¥re Hellan wrote: "When I told you to turn off the light at 10:30PM, you were also supposed to stop reading, dear" :-) Do y'all call that night or day? We'd probably stretch "evening" until midnight. After that it's "night", no matter how light. Actually, we don't speak English at all, of course. :-) |
Hamstick dipole for 80m
Jon KÃ¥re Hellan wrote:
Actually, we don't speak English at all, of course. :-) Us Texans don't palaver English neither. -- 73, Cecil http://www.w5dxp.com |
Hamstick dipole for 80m
In article ,
"HRBE" wrote: I made up a 4 band "spider" mount, to which you can screw in 4 sets of hamsticks. I have a full set of hamstick whips from 80m down to 6m. So I have a multiband hamstick dipole array! HRBE- I think it was the December, 2007, issue of QST that had an article on the "Octopus" antenna made of 4 pairs of mobile whips for 75/40/20/15 meters. I plan to also add a vertical 10 Meter whip. I've collected the parts but haven't assembled it yet. It will be interesting to see how the monstrosity works! Fred K4DII |
Hamstick dipole for 80m
Fred McKenzie wrote:
I've collected the parts but haven't assembled it yet. It will be interesting to see how the monstrosity works! Hope you enjoy 75m QRP. -- 73, Cecil http://www.w5dxp.com |
Hamstick dipole for 80m
In article ,
Cecil Moore wrote: Fred McKenzie wrote: I've collected the parts but haven't assembled it yet. It will be interesting to see how the monstrosity works! Hope you enjoy 75m QRP. Cecil- I can appreciate that a mobile whip used on an auto, does not have the efficiency of a full quarter wave vertical over an array of counterpoise wires. But it does work. I want to use a pair of mobile whips as a horizontal dipole. (Or more in the case of the Octopus.) Are you suggesting that such a dipole on 75 or 40 Meters, will not perform as well as just one of the whips mounted on an automobile? Fred K4DII |
Hamstick dipole for 80m
Fred McKenzie wrote:
I want to use a pair of mobile whips as a horizontal dipole. (Or more in the case of the Octopus.) Are you suggesting that such a dipole on 75 or 40 Meters, will not perform as well as just one of the whips mounted on an automobile? The radiation resistance of a 75m hamstick is roughly about 0.5 ohms. The feedpoint impedance is roughly about 20 ohms if one subtracts out the ground losses. Very roughly, that would make a 75m hamstick dipole have a radiation resistance of about 1 ohm and a feedpoint impedance around 40 ohms. That's about 2.5 watts out for 100 watts in. I would say that qualifies for QRP and is actually an improvement over a 75m mobile hamstick with a measured signal strength that is 12 dB down from a good screwdriver which itself is about 10 dB down from a 1/2WL dipole. Almost any other antenna in the world will beat a 75m hamstick dipole. One can radiate ten times as much power simply by lengthening it by 50% and using high-Q loading coils. -- 73, Cecil http://www.w5dxp.com |
Hamstick dipole for 80m
Cecil Moore wrote in news:2KTMj.8379$V14.7229
@nlpi070.nbdc.sbc.com: Fred McKenzie wrote: I want to use a pair of mobile whips as a horizontal dipole. (Or more in the case of the Octopus.) Are you suggesting that such a dipole on 75 or 40 Meters, will not perform as well as just one of the whips mounted on an automobile? The radiation resistance of a 75m hamstick is roughly about 0.5 ohms. The feedpoint impedance is roughly about 20 ohms if one subtracts out the ground losses. Very roughly, that would make a 75m hamstick dipole have a radiation resistance of about 1 ohm and a feedpoint impedance around 40 ohms. That's about 2.5 watts out for 100 watts in. I would say that qualifies for QRP and is actually an improvement over a 75m mobile hamstick with a measured signal strength that is 12 dB down from a good screwdriver which itself is about 10 dB down from a 1/2WL dipole. Almost any other antenna in the world will beat a 75m hamstick dipole. One can radiate ten times as much power simply by lengthening it by 50% and using high-Q loading coils. Hi: As I reported some time ago, I compared Hamstick dipoles to a full size dipole at about the same height. The Hamstick dipole was about 20d down from the full size antenna. The 2:1 SWR bandwidth was about 65KHz. They work as an antenna but are in the better than nothing class. John Passaneau W3JXP |
Hamstick dipole for 80m
John Passaneau wrote:
As I reported some time ago, I compared Hamstick dipoles to a full size dipole at about the same height. The Hamstick dipole was about 20d down from the full size antenna. So I was generous in estimating 2.5 watts radiated out of 100w input. In your case, it was more like 1 watt radiated out of 100w input. -- 73, Cecil http://www.w5dxp.com |
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