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Author Topic: Heavy weather directional  (Read 592 times)
CH62
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Posts: 24




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« on: December 06, 2017, 06:31:13 PM »

I live in an area where over the past 11 years I have measured sustained wind of 72mph at ground in the summer as hurricane Sandy came on shore and 1” of ice one Winter, with 7 of 11 producing at least one storm of 1/2” or more.  At least here at 1700ft just outside of Washington DC we live in a urban quite zone......needless to say, there are better places to design a DX ham station.

Are there examples of antennas in the 20-40m range that have survived something close to the conditions I experience or is it just a dream, or a project that is going to cost a lot of money and still not yield a positive result?  I would love to hear from anyone that have gone down this path and hopefully survived it.......
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CH62
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« Reply #1 on: December 07, 2017, 12:54:01 PM »

I had an email exchange with Tom, owner of Optibeam.  He feels that the XHD OB9-5 is up for the task, but for 40M, the dual element OB2-40 would best be beefed up a bit to ensure survival.

Does anyone have any experience with Momobeam?  If I am interpreting the information correctly, their antennas appear to build to a high mechanical standard.
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K1VCT
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Posts: 135




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« Reply #2 on: December 07, 2017, 04:38:52 PM »

Not directional, but it stood up to Irma.  We had a 60' oak tree come down onto the house, across the street, a large banyan tree came down on that house.  Two blocks over, a large oak tree came down too.  Using google maps, you can see they were all in one line... along with my antenna!



The antenna itself, had one spider leg pull off its screw that holds it.  I was easily able to straighten it, and reinforce all the spider legs.  The 40m trap slid down from the force of the guys being anchored above it.  But nothing broke, no water inside, and until about an hour before the tornado (or at least whirlwind) took down everything at the end of the storm, I was transmitting on it.

The base... broke its lagbolts from one leg, and folded like a NY pretzel.  Took two large grown men, a heavy bench, heavy 8" vice and a torch to pull it back into shape.  I could barely move the hot metal... so I have no idea how it bent.



Straight base, attach legs with carriage bolts instead of lags, fix one radial and we're back in shape.  Winds in excess of 120mph were estimated.

Tree damage.....




Not sure what you are looking for in DX as well, but the Hustler has gotten me to all over Europe, Mediterranean, Baltics, all of North America, northern South America, Caribbean, Pitcairn Island, Easter Island, and Osaka Japan, all from south Florida.

I'm very please with the robustness of that antenna
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CH62
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Posts: 24




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« Reply #3 on: December 07, 2017, 05:33:56 PM »

Well I doubt many tower based antennas made it through that.  Sure looks a lot more straightforward that a 120kg 3el sail flying 90 feet high.....and a lot less money as well.  Thanks for sharing the picture and story. Is that a 4BTV?
« Last Edit: December 07, 2017, 05:38:18 PM by CH62 » Logged
K1VCT
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« Reply #4 on: December 07, 2017, 06:27:02 PM »

Yup.   

And for what it's worth I didn't lose any of my Rohn Towers.  I've got about 20 of the 25G's up for customers..... Granted they only have UHF verticals on them about 6 feet long and the occasional iagi too.... But they're not guyed and up 60 ft
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CH62
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« Reply #5 on: December 07, 2017, 08:34:27 PM »

I’d like to know more about your radials.  Our soil here on top of the ridge is about as bad as it gets....lots of sandstone close to the surface...and if my understand is correct, to get a vertical to work well on DX I’ll need to pay close attention.  If my goal is 20/40m, would I look to a mix of 10/20m radials or would I be served better with all 20m?
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W0MLD
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« Reply #6 on: December 08, 2017, 03:05:31 AM »

Call JK antennas!  I’ve seen some photos of theirs with crazy ice loads and they spring back.  Ken has lots of experience with that.  I own a few and I won’t shop with anyone else now having experienced his customer service and product quality!
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CH62
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« Reply #7 on: December 08, 2017, 08:49:41 AM »

Thank you.  It looks like they fit the bill.
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K1VCT
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« Reply #8 on: December 08, 2017, 03:54:11 PM »

I’d like to know more about your radials.   if my understand is correct, to get a vertical to work well on DX I’ll need to pay close attention. 

I'm not the expert, but here's my story on radials.   I cut four radials per quadrant on my mount, making sixteen radials.  That gave me four each at every "suggested length" given by Hustler/NewTronics.

That worked really well... except when it rained.  When it rained, the resonance of the antenna rose about 500kc or so (from memory).  All sorts of suggestions were given here.  I called NewTronics, they were baffled (but nice to deal with and we had a long conversation).

So, I added another sixteen radials, bringing it up to 32 total.  The additional radials were cut to fit to the edge limit of the flat roof (about 32x32 feet).   Still works great.  Hardly rises in resonance at all when it rains.  There was obviously some interaction between large wet surface and radials.  Adding more... mitigated it.

I'm not sure if I'd get a fancy DX engineering plate for radials.  But I'd do at least 32 if I did it again, ground mounted.  The one accessory that is a real good one to have, is the UHF fitting adapter, which is a small curved plate that fits on the Hustler antenna and has prewired fittings for SO-239 (to plug in a PL-259), and for the center and braid of the coax.  Makes it REAL easy to disconnect your coax, worth every penny.  Forget tilt bases... the antenna is so light its easy to bring up, test, bring down, adjust a little, repeat.  I've lifted it dozens of times getting the tuning "just so".  Very easy to lift.  One last trick is to not use the equidistant distance settings on the lowest section (that fits the mount).  Just drop that section "down" onto the mount and put double distance on the top space of that section.  NewTronics agreed that's a much better way to go.  You leave the mount in place, and lift the antenna off the mount, adjust and return it to the exact same starting point every time.  I also replaced some of their hardware with better stainless.. but that was only a few $$ at Home Depot.

I can get fairly close contacts (under 200miles) in daytime on 40m and 20m, as well as DX on 20m and 15m.  Hard to find anything going on 10m but I've made contacts there that were into Georgia and N. Carolina from S Florida.  Very good DX on 20m.  At night, good DX on 40m

My first contact with that antenna was to upstate NY from Florida, second was to NJ - both at 100w on 20meters.

I'd love to have a long sloper, and big beam antenna... but it aint gonna happen on this piece of property.  Too many overhead wires.  So... I just use what I can, and it works ok.  There's always something better.  Its all about what tradeoffs have to be made.

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