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Slinky dipole HF antenna recommendations wanted.
On Sep 9, 10:51 pm, 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. Here is the eHam Review site (http://www.eham.net/reviews/detail/1077) for commercial Slinky Antennas. As you can see, they seem to work for some folks. Here's the site for the manufacturer (http:// www.usa2way.homestead.com/CliffDweller.html). 73 & GL, Tom K3MOV |
#12
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Slinky dipole HF antenna recommendations wanted.
Richard Clark wrote in
: 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. Two turns makes it 92 micro-ohms. 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. I'm not sure it is as wide as 2khz. LIS, it's not really suitable for SSB. It's OK on CW, though. 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. I'd not recommend it for low power. As an aside, I can't visualize the gimmick's relation to the inner/outer conductors. You have any close-up pictures? Look at Ted Hart's loop design in the old Antenna books. I sort of patterned it after that. The 80 meter 1-turn loop is a bit bigger and, of course works a bit better. Don't get me wrong, these were test-of- concept antennas and I don't use them for my working antennas. If I were to build a working loop for 80m, I'd do it out of 2-inch copper pipe and make it as large as practical. -- Dave Oldridge+ ICQ 1800667 |
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