Author Topic: 40 and 80 meters, one wire  (Read 2284 times)

0 Members and 1 Guest are viewing this topic.

rah

  • Jr. Member
  • **
  • Posts: 34
  • Karma: 4
  • Gender: Male
  • General Class Operator
40 and 80 meters, one wire
« on: February 22, 2012, 04:46:28 AM »
My 40 meter dipole is in sorry need of replacement. It has served me well for the past two years,
but I did not seal it's connectors and have driven over the coax numerous times everyday.  I've enjoyed
the contacts on that band, and want to continue, but also want to join with the people on 80 meters.
I have no limitations of space, just few trees.  I'm thinking. instead of running two separate wires for 40
and 80 meters, why not have them on the same wire.  Has anyone on the board had any experience with
the MFJ 17758 dual band antenna and how would you rate its performance.

austinrob

  • Jr. Member
  • **
  • Posts: 41
  • Karma: 3
Re: 40 and 80 meters, one wire
« Reply #1 on: February 22, 2012, 10:02:50 AM »
I built one of these on my roof and it works nicely. 

WA4STO

  • Whatcha Gonna do when they come for you?
  • Jr. Member
  • **
  • Posts: 46
  • Karma: 12
    • WA4STO on QRZ
All HF bands, one wire
« Reply #2 on: February 23, 2012, 10:13:43 AM »
I'm sure that most of the more experienced hams here already know this.  But for the newcomers...

A single dipole can be used to operate on ALL bands.  That is, all bands higher than the design of the dipole itself.  Thus, if you want to operate on 80 meters up through, say, six meters, you cut the dipole for 80 and you're good to go.

The key to your success there is how you feed RF power to the dipole.  If you use coaxial cable, you're pretty much stuck with a fairly small range of operating frequencies, usually on a single band.  But if you feed the dipole with open wire feed line through a manual tuner, you suddenly open the door to a bazillion frequencies, on a huge variety of bands.

Here's an example of open wire feed line in use.  Note that this stuff can be built DIY!  I see that there's even a Youtube vid that clearly shows how to build it.  Me, I buy it, but that's cuz I'm clumsy, half-blind, and a total DIY id-jit...



Notice that one side of the feed line goes to one side of the dipole; the other to the other.  Simple even for me to unnerstan'

Man, I wish I had that tower...

BTPost

  • Old Fart Ham
  • Prepper
  • Full Member
  • *
  • Posts: 361
  • Karma: 29
  • Gender: Male
    • Bruce's Trading Post
Re: 40 and 80 meters, one wire
« Reply #3 on: February 23, 2012, 07:32:40 PM »
I second the previous posters, comments. I have a single Dipole up at 60 Ft, cut for 3930 Khz, and have used that for decades, on 160-10 Meters, with the use of a GOOD Antenna Tuner. It worked so well, the Big Antennas, Towers, and Gear, that I brought with me when I moved out here, are still laying on the ground, where I put them, after unloading them out of the Conex Box. I can't say I have the Best Signal in the world, but my 120 Watts PEP, is heard whenever I return a CQ, that I can hear, and that is good enough for "Me"..... Just say'en... YMMV....
Bruce in alaska AL7AQ