KF9F Revives an OCF Dual Feed Multiband Dipole  This multiband 160 thru 10 Meter antenna design was adapted using the dual feedline
 technique from and old 73 Magazine Article published in 1984 by W4HDX**  

Note that both ends of the feedline are tied together and only grounded at the tuner end.

FEEDLINE LENTGH CALCULATION = 1.3 X WAVELENGTH / 4 FOR THE LOWEST FREQ.
Example - 3.9Mhz = 234 / 3.9  = 60 X 1.3 = 78' BUT IT ALSO WORKS 160 WITH THAT DIMENSION
I used a 3kw 4:1 air core balun to match the 50 ohm feedline
 going to the rollor inductor tuner.
The antenna loaded well on 160 - 10 meters. 


You can use this handy center insulator and feed line support by KF9F
 or use your own design.



Overall installation of the OCF dipole at 34 feet apex in inverted V fashion


Updated information from KF9F 11-14-2010

Since I first tried this antenna I have found two things.

 

1: It works as well, if not better, using a choke balun (mine is 20 ft. of RG 8 wound in a 1 Gal. Paint can) instead of the 4:1 balun as shown in the original diagram .      

                                        

2: For the Boy Scout J.O.T.A., I used the exact same setup as field day, only a different location (remote as opposed to urban).  Upon finishing I tuned up on the W.A.R.C. bands, and again, with a roller inductor transmatch, the thing loaded exceptionally on all freqs.

 

3: I mistakenly said to some of the guys here that RG 59 would be OK for 100 Watts or less, but that is presuming you use a tuner and insure low VSWR before going to full 100 W. just to be safe. 

 

  Now if there was just a way to rotate it................. 

**Footnotes: According to our research... the article in February, 1984, 73 Magazine was originally written by J. W. Spencer, W4HDX, as printed in the upper left portion of the article in that magazine.
There appears to be some conflict with the author's call sign on other websites.

It has been reported (on other websites) that the correct call sign is W4HDL, but this call sign is registered with the FCC in another name than the original author of the article.  According to our research, the correct call sign should be, W4HDX. The author's name in the article and call sign do seem to match on QRZ.COM. http://www.qrz.com/db/
The original article used the same dual coax feedline technique but used 50 ohm coax and the antenna was a balanced antenna, (equal side lengths), not an off center fed type like the above projects uses. KF9F is using the idea for the W4HDL dual feeds and not the original balanced antenna in the project above.

We want to credit KF9F for reviving this OCF antenna and W4HDX for his dual feed line idea and for sharing it with us! NO PART OF THIS ARTICLE MAY BE USED ON OTHER WEBSITES WITHOUT WRITTEN PERMISSION! 73, N4UJW

Questions? Email Richard, KF9F here.... richaz at charter.net  

Further reading on the dual coax feeder design can be seen on the KB0SK site here! Look on the right side of the page....click on each image. They can be magnified.