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Converting a 80M dipole to 160M ?

Jan 5th, 12:24

hamwillyt

Joined: Nov 30th 2015, 19:06
Total Topics: 0
Total Posts: 0
Hi and I'm new to to this fun hobby and have an ICOM 7300. I've installed a 5GRV (6M to 80M) in north / south direction and a simple 80M dipole that runs in east / west direction. I really don't find much of a difference monitoring and successfully transmitting on 80M between the two antennas.

So, is it possible to simply "add correct lenght of bare wire" to the simple 80m dipole to so it works at 160M

Thanks,
Bill
Jan 5th, 14:29

W1VT

Joined: Apr 4th 1998, 00:00
Total Topics: 0
Total Posts: 0

You need to add about 66' on each side of the dipole.

An 80M dipole is typically around 125 feet from end to end, while a 160M dipole needs to be around 257 feet from end to end. The exact length will vary depending on height above ground and wire insulation. The demo version of EZNEC can be used to calculate a more accurate starting value than the traditional 468/f formula.

Zack Lau W1VT
ARRL Senior Lab Engineer
Feb 9th, 10:20

WA7PRC

Joined: Jul 27th 2011, 03:48
Total Topics: 0
Total Posts: 0
Another trick is to drive your 80m dipole as a vertical with a "top hat" on 160m. By shorting the feedline at the bottom, you are now driving it against ground (it is now a vertical antenna). You now need a good radial system. If the feedline is close to one quarter wavelength on 80m, the overall length on 160m is about one quarter wavelength, and easily tuned.

I did exactly that w/ my 80m cage inverted vee. My feedline is about 85', and the ATU built into my Kenwood TS850SAT easily tunes it on 160m. I use a SPDT vacuum relay to do the switching at my ground bus outside the shack. Photos & text are on my Flickr page: http://www.tinyurl.com/wa7prc-80m-160m

vy 73,
Bryan WA7PRC

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