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Post by cbrown on Apr 12, 2012 8:40:20 GMT -5
Looks like a nice design. You have any high winds in your area?
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Post by homerbb on Apr 12, 2012 12:00:27 GMT -5
Oh, yes. When the fronts we get in Tornado Alley come through, the can have gust anywhere from 45 to 90 MPH. I have added the platform to work from to the top of the wooden section. As with all things I do, there is a little at each stage that tells me I have a little more to do. I am going to add some more guys, especially at the top of the wood section, if I'm going to send any time on that platform. I have been on it already, but want the added assurance that it remains rock steady when I am up there.
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Post by cbrown on Apr 13, 2012 9:02:49 GMT -5
If that setup stand up to 90 MPH guts, you are doing it right!
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Post by homerbb on Apr 13, 2012 16:59:26 GMT -5
One suggestion: When you make the matching coil, try and get the spacing between each coil to be equal. Also the length of the coil will affect the overall height of your antenna when tuning to specific frequencies. Thanks! I'll keep that in mind. I made my first 43 div contact with the .64 homebrew today. Peter_43WR789-----Melbourne,AU and I got connected on .385 and QSY .405 Conditions could have been better, but I felt good about it under the circumstances of being in a DX drought my way.
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Post by cbrown on Apr 16, 2012 8:27:22 GMT -5
Nice contact!
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Post by homerbb on Apr 17, 2012 1:04:11 GMT -5
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Sandbagger
Administrator/The Boss
Posts: 6,250
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Post by Sandbagger on Apr 17, 2012 6:23:54 GMT -5
Up on the platform working on the antenna again. That's a great way to work on and adjust antennas. And wooden platforms and supports will not interact with the radiation pattern.
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Post by homerbb on Apr 17, 2012 8:15:43 GMT -5
I was a bit nervous over standing up there at first, but a couple of trips up there and that was over with. I intend to get me a safety harness rigged up on it, too.
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Post by cbrown on Apr 17, 2012 9:54:33 GMT -5
I'm the same way with heights. Looks like a pretty stable platform!
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Post by homerbb on Apr 17, 2012 16:50:53 GMT -5
I'm the same way with heights. Looks like a pretty stable platform! Yep. As steady as the mast itself.
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Post by homerbb on Apr 17, 2012 19:02:30 GMT -5
Worked on the antenna some more, and not so sure I've noted any improvements from the analyzer standpoint. I put on a cap hat just to see if it made any measurable difference. It has an overall diameter of 14". I had to work at an acceptable shortening length for the antenna vertical, and ended up a mere 10" shorter than previous to installing the thing. I also went back to a smaller nearly square coil modeled from the Shockwave antenna coil - 4.5" tall x 4" OD x 6 exact wraps. This is around the vertical rather than off to the side as I usually do. It may get changed . . . I sat on the platform with the antenna at 18.5' and attempted to tune it with the single 1/2λ coax until I felt I was too tired to continue and said good enough for now. 27.400 was a 1.2 SWR, R43, x8 when working there. So here's the result with the antenna at 34' elevation, and using first the 6 x 1/2λ coax. and then measuring from the shack. I scoped the P/U pole out an additional 15.5' and climbed down to take some measurements. Here they are:
------------1/2λ x 6 coax -------------------------------------------------- at Shack end of coax run
2.0 --- 24.214 --- R27 -- X13 ------------------------------------------ 26.262 --- R72 -- X41 1.5 --- 26.439 --- R44 -- X20 ------------------------------------------ 26.647 --- R48 -- X20 1.2 --- 26.965 --- R40 -- X6 ------------------------------------------- 1.0 -------- R46 -- X2 1.1 --- 27.185 --- R42 -- X2 -------------------------------------------- 1.2 -------- R51 -- X10 1.1 --- 27.400 --- R45 -- 0 ---------------------------------------------- 1.4 -------- R62 -- X16 1.0 --- 27.555 --- R47 -- X3 -------------------------------------------- 1.5 -------- R66 -- X29 1.5 --- 28.728 --- R39 -- X15 ------------------------------------------ 28.210 --- R74 -- X14 2.0 --- 29.374 --- R25 -- X5 -------------------------------------------- 28.600 --- R82 -- X35
Best: 27.732 -- 1.0 R55 X0 --------------------------------------------------- 26.983 -- 1.0 R46 X1
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Post by cbrown on Apr 18, 2012 8:27:42 GMT -5
Do you notice much signal strength difference between the changes? I like the top hat design, too.
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Post by homerbb on Apr 18, 2012 8:32:08 GMT -5
Do you notice much signal strength difference between the changes? I like the top hat design, too. Right now the locals are light on doing radio, and the DX conditions are poor to none, so I am just working the analyzer readings. More than likely the top hat will stay. It looks cool ;D
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Post by homerbb on Apr 18, 2012 11:45:28 GMT -5
I took some much more gradual readings of the antenna in its latest configuration today @ 34' elevation:
29.350----2.0----R24--X4 29.250----2.0----R25--X2 29.150----1.9----R26--X5 29.050----1.8----R28--X8 29.000----1.7----R29--X10 28.950----1.7----R30--X12 28.900----1.7----R32--X12 28,850----1.6----R34--X14 28.800----1.1----R57--X2 27.950----1.1----R57--X0 27.900----1.1----R56--X0 27.850----1.1----R57--X0 27.800----1.0----R56--X0 27.750----1.0----R54--X0 27.700----1.0----R53--X2 27.650----1.0----R51--X3 27.600----1.0----R50--X3 27.550----1.0----R48--X3 27.500----1.0----R46--X2 27.450----1.1----R45--X1 27.400----1.1----R45--X1 27.350----1.1----R44--X0 27.300----1.1----R43--X0 27.250----1.1----R43--X0 27.200----1.1----R42--X2 27.150----1.2----R42--X3 27.100----1.2----R41--X4 27.050----1.2----R41--X5 27.000----1.2----R40--X5 26.950----1.2----R40--X6 26.900----1.3----R40--X6 26.850----1.3----R39--X7 26.800----1.3----R39--X9 26.750----1.3----R39--X10 26.700----1.4----R40--X12 26.650----1.4----R39--X13 26.600----1.4----R40--X15 26.550----1.5----R41--X16 26.500----1.5----R42--X18 26.450----1.5----R43--X19 26.400----1.5----R44--X21 26.350----1.6----R45--X23 26.300----1.6----R47--X24 26.250----1.6----R49--X26 26.200----1.7----R51--X27 26.150----1.7----R55--X28 26.100----1.7----R58--X29 26.050----1.7----R61--X30 26.000----1.8----R65--X30 25.950----1.8----R69--X30 25.900----1.8----R73--X30 25.850----1.9----R79--X29 25.800----1.9----R84--X26 25.750----1.9----R90--X22 25.700----1.9----R95--X15 25.650----2.0----R100-X0[b
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Post by cbrown on Apr 19, 2012 8:36:21 GMT -5
Right now the locals are light on doing radio, and the DX conditions are poor to none, so I am just working the analyzer readings. More than likely the top hat will stay. It looks cool ;D It does look cool! Did you notice any decrease in background static noise when you changed?
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Post by homerbb on Apr 19, 2012 8:46:45 GMT -5
Right now the locals are light on doing radio, and the DX conditions are poor to none, so I am just working the analyzer readings. More than likely the top hat will stay. It looks cool ;D It does look cool! Did you notice any decrease in background static noise when you changed? Nope. Seemed the same.
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Post by cbrown on Apr 20, 2012 10:10:11 GMT -5
No increase, though.
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Post by homerbb on Apr 20, 2012 14:42:49 GMT -5
No increase. Today, the white noise seems less, but it will take some listening over time to determine whether it is conditions or the antenna difference.
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Post by cbrown on Apr 23, 2012 8:47:00 GMT -5
I never really investigated the differences in cap hat design. I may look into it.
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Post by homerbb on Apr 23, 2012 9:28:36 GMT -5
There's some good reading online about it.
Adding it simply came from noticing one on some of the well respected antennas on the market. So why not?
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Post by homerbb on Apr 23, 2012 21:14:22 GMT -5
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Post by cbrown on Apr 24, 2012 8:33:22 GMT -5
You seems to be pretty high up on that matching coil with the feed, is that where the MFJ 259B says you should be?
One of the more interesting cap designs I ever saw was on my first CB antenna. My dad bought both the radio and the antenna from the local Lafayette store. It was their 'Range Boost" half wave antenna and on the top it had what they called a Static Clover Leaf (three rings).
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Post by homerbb on Apr 24, 2012 13:42:48 GMT -5
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