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Author Topic: Dipole install  (Read 840 times)
KC4YWW
Member

Posts: 11




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« on: March 29, 2013, 11:58:47 PM »

Greetings.  I recently purchased a 80-6 OCF dipole with an OCF Windom vertical radiator.  I am planning on attaching the center and coax to my tower at 36 feet height which is on the north side of my house, right against the roof edge.
My question is, can I place the other two ends on the edge of the roof?  One on the front edge of the roof and the other on the back edge?  Does the antenna have to be straight in line with the center or can I stretch them back towards the roof?  Is there an angle I have to keep?
Thanks
Pete
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W1JKA
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Posts: 1616




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« Reply #1 on: March 30, 2013, 03:27:35 AM »

   Two months ago I rerouted my new Carolina type windom by offsetting the long side by about 30 degrees from straight and also raised it's end by about 7 ft.higher than the vertical radiator center point.On air operating I have noticed no difference in SWR or contacts.I'm sure the experts will weigh in with the technicalities of doing so such as possible changes in SWR,Lobes,being over a roof,etc..Just try it and find out for yourself.I know a few other hams that have OCFs and dipoles in both horizontal and vertical vee shape slope combinations that work fine for them.GL
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K3VAT
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Posts: 699




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« Reply #2 on: March 30, 2013, 05:17:24 AM »

... can I place the other two ends on the edge of the roof?  One on the front edge of the roof and the other on the back edge? 

Yes, you can place the ends on any convenient attachment, but try and keep several feet between the antenna's end insulator and the building (the ends of the often are the area of highest voltage).

Does the antenna have to be straight in line with the center or can I stretch them back towards the roof?  Is there an angle I have to keep?

No, it may be configured with one or more 'bends' and still perform adequately.  W1JKA mentioned "... ~ 30 degrees from straight ...", this should be 'acceptable', but I wouldn't go much beyond this if possible.  You can even 'zig-zag' the antenna to get the antenna in to fit your physical typology.

Note: as you stated that the antenna height (center) will be "36 feet" don't expect stellar performance on the lower bands.  30M and up (10, 12, 15, 17, and 20) should yield you decent DX contacts across to nearby continents, but for 40M and certainly for 80M  the vast amount of your radiation will be straight up even though there is a bit of a vertical component due to the Windom's 22' vertical radiator.  The best success for the lower bands (40M and 80M) with these Windoms is when you can manage the get both the center and the ends up to heights > 65 feet; although some users have reported remarkable DX contacts (such as working deep into SE Asia) with heights the same as you are using.

GL, 73, Rich K3VAT
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K7KBN
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Posts: 2754




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« Reply #3 on: March 30, 2013, 10:42:31 AM »

The only way to know for sure if it will "work" is to put it up and try it.  Make notes of exactly what you have and contacts made/times, etc.  Then make one change at a time (if you think changes are necessary or even if you want to do some interesting experiments).  Note differences in signal strengths, changes in your SWR and such.  Then make one more change, if necessary, and do it again.
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73
Pat K7KBN
CWO4 USNR Ret.
NV2A
Member

Posts: 102




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« Reply #4 on: April 01, 2013, 01:16:24 PM »

The only way to know for sure if it will "work" is to put it up and try it.  Make notes of exactly what you have and contacts made/times, etc.  Then make one change at a time (if you think changes are necessary or even if you want to do some interesting experiments).  Note differences in signal strengths, changes in your SWR and such.  Then make one more change, if necessary, and do it again.

I fully agree.  Most times we talk about antenna installations we are describing "optimum" installs.  Many times, especially if you have a tuner, you can get the wierdest things to radiate RF whether it's optimal or not.  You can make contacts and have fun until you can figure out something more suited to your needs.  Perfection is only a goal and sometimes only serves to make things harder for us.  If you desire is to talk to a buddy in the next state over you can likely do that on a bedspring with the aide of a decent tuner. If your prime desire is DX then you have a lot of work to do Wink
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