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Message |
    
Charliebrown
Intermediate Member
Username: Charliebrown
Post Number: 226
Registered: 10-2002
| | Posted on Saturday, September 17, 2011 - 7:44 am: | 
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Year's ago the old timer's would use open line for the connection to their antenna. Some were long run's and some were short. I like to play around with different idea's to try to learn more. But, I alway's try to ask here to see what everyone else had done or known so my time or money is not a total waste. So, here is my question, INSTEAD OF OPEN WIRE COULD A PERSON USE 12 GAUGE ELECTRICAL WIRE WITH THE WIRE INSULATION STILL ON BUT, SPACED AS THE OLD OPEN WIRE USE TO BE FOR ANTENNA WIRE? O.k. people. Have any tried this or what do the TECH'S think or know about this. The old timer's use to swear by the open wire but also had a lot to complain about the open wire because of thing's falling on the wire changing the swr. |
Tech833
Moderator
Username: Tech833
Post Number: 2047
Registered: 8-2002
| | Posted on Saturday, September 17, 2011 - 12:10 pm: |
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Yes. However, keep in mind that the wire size will determine the spacing for a desired impedance.
Leaving the insulation on will lower the velocity factor.
Your radio 'Mythbuster' since 1998
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Tech237
Moderator
Username: Tech237
Post Number: 1473
Registered: 4-2004
| | Posted on Saturday, September 17, 2011 - 10:45 am: |
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Open wire feedlines are generally lower loss than coaxial styles, but yes they are more prone to be effected by nearby objects, especially one that conduct, than the shielded coax.
As long as you use correct impedence matching at both end, there is no reasin why you cannot use open line feeders, as long as all recommended precautins are taken.
This would include - now nearby conductive object (and that includes trees), no unneccassary bends, and those thar are needed are large radius smooth flowing ones. There are othes, but I am at work and cannot recall off the top of the head what else you should watch for. I"m sure 833 will chip in with other precautions.
Tech237
N7AUS
God only made some many perfect head, on the rest he put hair.
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Funtimebob
Intermediate Member
Username: Funtimebob
Post Number: 305
Registered: 5-2002
| | Posted on Saturday, September 17, 2011 - 11:14 am: |
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Open line has its advantages/disadvantages just like any other feed line/Coax.
You didn't mention what type of antenna you were wanting to try it with.
The impedance of the open wire line depends on the spacing between the 2 conductors.
I wouldn't try feeding a ground plane with it but you could always play around with a dipole fed into a tuner.....
Probably a waste of time on a single band BUT if you need a multi band antenna......
Dyslexics of the world UNTIE!
73 De Bubba Honorary O.F.
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Tech833
Moderator
Username: Tech833
Post Number: 2049
Registered: 8-2002
| | Posted on Saturday, September 17, 2011 - 12:19 pm: |
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If you want to see a great argument AGAINST using open wire feedlines, go to YouTube and put this search in the search box: "open wire feedlines in wind"
That is why we use coax for all but the ultra high power SW stations these days. Can you imagine trying to keep the transmitters on the air with the SWR jumping all over the place?
Your radio 'Mythbuster' since 1998
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Charliebrown
Intermediate Member
Username: Charliebrown
Post Number: 227
Registered: 10-2002
| | Posted on Saturday, September 17, 2011 - 12:44 pm: |
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This is just a project I had thought I might try. With the pro's and con's involved it would most likely be more work than pleasure. I of course had plan to use my max 2000 for the antenna and then an inverted v antenna. This is something I had never done and thought it would be fun to try. I am glad to see those that had respond with the information and help so far. I will look at the information on you tube and see if I can get any more information before I decide if this is worth while as a fun project or not. THANK'S FELLOW'S. |
Tech833
Moderator
Username: Tech833
Post Number: 2050
Registered: 8-2002
| | Posted on Sunday, September 18, 2011 - 12:40 pm: |
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Understood.
If you want something to constantly tinker with, then it might be fun.
From my open wire feedline experience, be prepared for:
Off the air due to snow or ice.
Off the air due to wind.
Off the air due to birds sitting on it.
Off the air due to breakage.
In the extreme high power shortwave world, we have crews that do nothing but maintain the lines. Not so bad when you have a crew on site all the time.
Your radio 'Mythbuster' since 1998
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Charliebrown
Intermediate Member
Username: Charliebrown
Post Number: 228
Registered: 10-2002
| | Posted on Sunday, September 18, 2011 - 4:34 pm: |
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TECH 833, You just help me make up my mind. Not worth that much time or trouble for sure. Thank's to you and the other's. |
