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Slinky dipole HF antenna recommendations wanted.
I bought 2 Slinky's to put a Slinky antenna together, and would love to get
comments and suggestions, (construction detail tips, care and feeding, etc.) from anyone who has tried this type of antenna before. I live in a second floor apartment and have limited HF antenna options. I would love to hear recommendations for any other HF antenna designs that would work well in this type of setting. Thanks. |
Slinky dipole HF antenna recommendations wanted.
On Sun, 09 Sep 2007 22:51:54 -0400, RJG wrote:
I bought 2 Slinky's to put a Slinky antenna together, and would love to get comments and suggestions, (construction detail tips, care and feeding, etc.) from anyone who has tried this type of antenna before. I live in a second floor apartment and have limited HF antenna options. I would love to hear recommendations for any other HF antenna designs that would work well in this type of setting. Classic wire-wound, air-cooled resistors. You could do better with the various 1 meter diameter loops sold commercially. Some might suggest mobile screwdriver designs clamped to your balcony railing, but that isn't really the same sort of metal bulk equivalent to a, say, Chevy Suburban which would be the principal radiator. On a comparable price basis, the loops will be a better investment for 40M and up (I don't recall any that suggest they cover 80M and certainly 160M is beyond the realm). A simple test for small (for their wavelength) antennas is to measure their bandwidth. We will take the Slinkies as an example (and certainly cheap enough to test this statement, and to see how they perform both). A small antenna that would be efficient will also exhibit a high Q. The loops mentioned, as I recall, generally exhibit 5 to 10KHz bandwidth. For the most part, they exhibit some of the better efficiencies (although not as high as a standard dipole). The slinkies stand to have a wider bandwidth due to their loss (small wire AND steel wire). Initially, this may seem to be quite attractive, and if you ignore the loss, they may serve your purpose quite well (SWR and Loss are not always limitations to enjoying the hobby). As I said, cheap enough to simply plunge on and worry about efficiency later. Tune-up can be as simple as stretching/compressing the coils until you achieve a match (at least that has been my experience). If the frequency is too low, add more slinkies. If you want to beef up the efficiency with a slinky, make it(them) part(s) of a center loaded element(s). Unfortunately that means more room than you have in your apartment situation. 73's Richard Clark, KB7QHC |
Slinky dipole HF antenna recommendations wanted.
RJG wrote:
I bought 2 Slinky's to put a Slinky antenna together, and would love to get comments and suggestions, (construction detail tips, care and feeding, etc.) from anyone who has tried this type of antenna before. Maybe a better question would be: How many readers know of anyone who has tried a Slinky antenna and hasn't discarded it? IMO, one can always do better than a Slinky dipole. -- 73, Cecil http://www.w5dxp.com |
Slinky dipole HF antenna recommendations wanted.
"Cecil Moore" wrote in message ... RJG wrote: I bought 2 Slinky's to put a Slinky antenna together, and would love to get comments and suggestions, (construction detail tips, care and feeding, etc.) from anyone who has tried this type of antenna before. Maybe a better question would be: How many readers know of anyone who has tried a Slinky antenna and hasn't discarded it? IMO, one can always do better than a Slinky dipole. Perhaps, but I put one together about 30 years ago, hung it on the apartment wall (inside), and made lots of contacts with it. I just stretched it or compressed it until the SWR was reasonable. I recall that the tuning was indeed pretty broad, so I suppose that there was more loss than you might see with a more conductive wire -- or it could have been due to the effects of the adjacent wood and plaster. Actually, I may not have had an SWR meter, but instead tuned the output tank of my Heath Apache for peak and dip. I miss that boat-anchor. Still, it was small, and it worked well enough to get me on the air. I think I used two slinkys soldered together for each leg of the dipole, and stretched them out to about 15 feet. I operated on 40 meters. There are better small antennas, but sometimes "good enough is perfect". -Paul, wb6cxc |
Slinky dipole HF antenna recommendations wanted.
RJG wrote:
I bought 2 Slinky's to put a Slinky antenna together, and would love to get comments and suggestions, (construction detail tips, care and feeding, etc.) from anyone who has tried this type of antenna before. I live in a second floor apartment and have limited HF antenna options. I would love to hear recommendations for any other HF antenna designs that would work well in this type of setting. Thanks. If like me you live in an apartment and cannot erect external antennas but do have access to a loft (or have a very small garden) then a slinky may well enable you to put out a signal on one of the LF bands. In my case I wanted to able to work the UK and into Europe on the 80m band. You see what I did at http://www.radiowymsey.org/FanDipole/slinky.htm Of course it's a compromise and an 80m dipole would be much better but it will work and you will get a signal out. Charlie. -- M0WYM www.radiowymsey.org |
Slinky dipole HF antenna recommendations wanted.
charlie wrote:
Also, take a look at the fan dipole at http://www.radiowymsey.org/FanDipole/fandiploe.htm , this antenna gets me out on all bands from 40m to 6m and I have worked the US, Canada and North Africa from Southern England (10w SSB). Charlie. -- M0WYM www.radiowymsey.org |
Slinky dipole HF antenna recommendations wanted.
On Sep 10, 2:47 am, Richard Clark wrote:
On Sun, 09 Sep 2007 22:51:54 -0400, RJG wrote: I bought 2 Slinky's to put a Slinky antenna together, and would love to get comments and suggestions, (construction detail tips, care and feeding, etc.) from anyone who has tried this type of antenna before. I live in a second floor apartment and have limited HF antenna options. I would love to hear recommendations for any other HF antenna designs that would work well in this type of setting. Classic wire-wound, air-cooled resistors. You could do better with the various 1 meter diameter loops sold commercially. Some might suggest mobile screwdriver designs clamped to your balcony railing, but that isn't really the same sort of metal bulk equivalent to a, say, Chevy Suburban which would be the principal radiator. On a comparable price basis, the loops will be a better investment for 40M and up (I don't recall any that suggest they cover 80M and certainly 160M is beyond the realm). A simple test for small (for their wavelength) antennas is to measure their bandwidth. We will take the Slinkies as an example (and certainly cheap enough to test this statement, and to see how they perform both). A small antenna that would be efficient will also exhibit a high Q. The loops mentioned, as I recall, generally exhibit 5 to 10KHz bandwidth. For the most part, they exhibit some of the better efficiencies (although not as high as a standard dipole). The slinkies stand to have a wider bandwidth due to their loss (small wire AND steel wire). Initially, this may seem to be quite attractive, and if you ignore the loss, they may serve your purpose quite well (SWR and Loss are not always limitations to enjoying the hobby). As I said, cheap enough to simply plunge on and worry about efficiency later. Tune-up can be as simple as stretching/compressing the coils until you achieve a match (at least that has been my experience). If the frequency is too low, add more slinkies. If you want to beef up the efficiency with a slinky, make it(them) part(s) of a center loaded element(s). Unfortunately that means more room than you have in your apartment situation. 73's Richard Clark, KB7QHC Speaking of loops, does anyone have experience with any of these: http://www.universal-radio.com/catal...ants/4465.html |
Slinky dipole HF antenna recommendations wanted.
Richard Clark wrote in
: On Sun, 09 Sep 2007 22:51:54 -0400, RJG wrote: I bought 2 Slinky's to put a Slinky antenna together, and would love to get comments and suggestions, (construction detail tips, care and feeding, etc.) from anyone who has tried this type of antenna before. I live in a second floor apartment and have limited HF antenna options. I would love to hear recommendations for any other HF antenna designs that would work well in this type of setting. Classic wire-wound, air-cooled resistors. You could do better with the various 1 meter diameter loops sold commercially. Some might suggest mobile screwdriver designs clamped to your balcony railing, but that isn't really the same sort of metal bulk equivalent to a, say, Chevy Suburban which would be the principal radiator. On a comparable price basis, the loops will be a better investment for 40M and up (I don't recall any that suggest they cover 80M and certainly 160M is beyond the realm). I made a 160m loop out of LMR400, using the capacitance of the inner-to- outer conductor to resonate it. Made it two turns and wound a gimmick match out of flat 4-wire phone cable onto it to fire it up. Very narrow, but reasonably effective. Better than a hamstick, I think. It's about 3 feet in diameter. My normal 80-10 meter set-up is a hamstick horzontally off the balcony rail. The rail backs onto a stucco wall with underlying mesh, so the "ground" although tilted sideways is vastly larger than the average car. I'm going to try a screwdriver there because I like the idea of being able to change bands from the operating position instead of needing to go outside in whatever weather is happening at the moment. A simple test for small (for their wavelength) antennas is to measure their bandwidth. We will take the Slinkies as an example (and certainly cheap enough to test this statement, and to see how they perform both). A small antenna that would be efficient will also exhibit a high Q. The loops mentioned, as I recall, generally exhibit 5 to 10KHz bandwidth. For the most part, they exhibit some of the better efficiencies (although not as high as a standard dipole). Yes, my 160m loop is almost too narrow for SSB. -- Dave Oldridge+ ICQ 1800667 |
Slinky dipole HF antenna recommendations wanted.
On Wed, 12 Sep 2007 22:20:43 GMT, Dave Oldridge
wrote: I made a 160m loop out of LMR400, using the capacitance of the inner-to- outer conductor to resonate it. Made it two turns and wound a gimmick match out of flat 4-wire phone cable onto it to fire it up. Very narrow, but reasonably effective. Better than a hamstick, I think. It's about 3 feet in diameter. .... Yes, my 160m loop is almost too narrow for SSB. Hi Dave, Radiation resistance for a 1 meter loop at 1800 KHz is 23 microOhms. If I were to interpret your BW to be 2 KHz (an antenna Q of 900); then the Ohmic resistance would be 0.0225 Ohms (0.002 Ohms/foot). This resistance is on par with #13 wire which has considerably less surface area than the LMR400. The added resistance resides, undoubtedly, in connections (or maybe the gimmick); and if you drove it out, you might find your loop suitably more efficient for CW-only. Unfortunately, it might become an arc-gap transmitter. As an aside, I can't visualize the gimmick's relation to the inner/outer conductors. You have any close-up pictures? 73's Richard Clark, KB7QHC |
Slinky dipole HF antenna recommendations wanted.
A Slinky dipole is an excellent illustration of the fact that we use a
lot more power than we need to. As some folks have pointed out, most of the power you send to it ends up as heat. As others have noted, you can still talk to lots of stations with it. If everybody would use one, it would drop the QRM level a lot. Roy Lewallen, W7EL |
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