| Author |
Message |
    
Ozfisho
New member
Username: Ozfisho
Post Number: 1
Registered: 4-2012
| | Posted on Saturday, April 28, 2012 - 10:39 pm: | 
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Hi all, newby down under here. I've just started to get back into radio after many years lay off, blame internet!! Anyway, I built a longwire antenna back in the 90's due to not being able to push up anything else due to being in a rental, so I knocked up this longwire I read about someplace, but cant think of the details. It was made for around 27.405mhz and was around 15m long all up. The tail or -ve section was about 2.7m long to the insulator and the remainder was around 12.2m long. The feed coax was 75ohm and this was a specific length also and joined to my RG213 via a connector. This antenna worked exceptionally well and I would like to build it once again, building my antennas was always an enjoyable part of the hobby. So, in saying all that, if anyone can help me with the dimensions I need, or better still, pass on the name of the book / magazine I might have found this antenna in, it would be much appreciated.
73's
Cheers
Dale
Busselton
Western Australia |
Scooterman
Junior Member
Username: Scooterman
Post Number: 17
Registered: 3-2012
| | Posted on Sunday, April 29, 2012 - 11:23 am: |
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Get the AARL antennae book and it will tell you all you want to know, or check this website for instruction. http://www.ac6v.com/antprojects.htm |
Funtimebob
Intermediate Member
Username: Funtimebob
Post Number: 369
Registered: 5-2002
| | Posted on Sunday, April 29, 2012 - 3:26 pm: |
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A true long wire needs to be at least 1 wavelength long at the lowest frequency.
Was the antenna itself made from twinleed? One side used as the antenna, the other half used as the counterpoise?
The 75 ohm coax was probably a 1/4 wave matching stub.
Alles ist besser mit Soße!
No I'm not a Tech,I just know enough to be a nuisance.
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Tech237
Moderator
Username: Tech237
Post Number: 1571
Registered: 4-2004
| | Posted on Monday, April 30, 2012 - 10:50 am: |
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There is an article on here under Subscriber Articles that walks you through making an 11m Longwire. How do I know? I wrote it.
Tech237
N7AUS
God made me an athiest, who are you to question his wisdom?
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Ozfisho
New member
Username: Ozfisho
Post Number: 3
Registered: 4-2012
| | Posted on Sunday, April 29, 2012 - 9:35 pm: |
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G'day again guys, thanks for the feedback, I reckon we're close now Bob, the antenna was made from a single strand of copper wire, probably about 2mm thick, whatever gauge that is. The matching stub sounds about right too. As for twin leed, I'm unfamiliar with that, but it sounds a bit like the 300ohm ribbon cable that the old TV's used to use. So no, never used that before. Is that wire good for a longwire though? I might try it if it is.
Cheers
Dale
Busso
WA |
Buggly
New member
Username: Buggly
Post Number: 6
Registered: 4-2012
| | Posted on Monday, April 30, 2012 - 9:36 pm: |
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Considering, The measurements you have described. and that "27.405" is "AM channel 40 CB" Radio here in the U.S of A. It sounds like
You may of built a 5/4 wavelength "Longwire Antenna" that was trimmed to "specs". Funtimebob hit the nail on the head. It sounds like it was an 'end fed' 5/4 wavelength "longwire and or dipole" that had a "maybe 75 ohm" Counterpoise "at 1/4 wavelength forward of the feed point, to be able to "TUNE" your swr's. My algerbra is not spec on.
But I may suggest, was it possible that you may of had a " 300 ohm "Twin lead" piece of feed line in at the 1/4 wavelength so as to be able to move the 300 ohm lead along the wire to "tune" Proper SWR's?
The next lengths would be 7/4's,9/4's,11/4's...ect. And you can center feed them,"like a simple dipole"and or end feed them with the tuning at the proper "usually 1/4 to wavelength". If you need info on dipoles in any "array" the internet has many.
It has allways been a special place for me with "longwire" setups when I had the realestate to do so...
I have loads of wire antenna info,
I hope this helps.
73's
Doug. |
Ozfisho
New member
Username: Ozfisho
Post Number: 7
Registered: 4-2012
| | Posted on Monday, May 14, 2012 - 3:31 am: |
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Update: Built the longwire down in the workshop over the weekend to the sizes I've got from here and what I could recall about my original one, pulled it all up today, plugged it all in to the radio, quick SWR check on 27.405 and low and behold, 1.3 to 1.4 straight up. Back down to 27.355 for a quick radio check, and worked straight into Victoria on Australia's southeast corner 2700ks or 1600 miles away. Got to be happy with that. Probably needs aligning a little more to the east for me to work the east coast proper though. Now, onto the monster quad when I fly back home from work next week for hopefully a similar result.
73's and Cheers
Dale
West Oz |
Charliebrown
Intermediate Member
Username: Charliebrown
Post Number: 262
Registered: 10-2002
| | Posted on Friday, May 18, 2012 - 11:35 pm: |
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Were you able to go vertical with the long wire? If so how were the contact's? |
Charliebrown
Intermediate Member
Username: Charliebrown
Post Number: 263
Registered: 10-2002
| | Posted on Friday, May 25, 2012 - 7:43 am: |
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Ozfisho, The reason I had ask if you had use the log wire vertical is I have some tree's eighty foot tall to hag it from and if anyone had any great success I would like to try my luck at this. I have a MFJ 986 tuner and I could use the long wire on many freq's. Hey fellow's any one had any luck with a long wire vertical?? |
Tech237
Moderator
Username: Tech237
Post Number: 1583
Registered: 4-2004
| | Posted on Friday, May 25, 2012 - 9:38 am: |
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Yes, on 2m. 1-1/2 waves vertical. was l;ousey for local work, but consistantly hit repeaters 100-150 miles away, and I was at sea level at the time.
Tech237
N7AUS
God made me an athiest, who are you to question his wisdom?
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