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Author Topic: Need 80-10 m wire antenna help (how to).  (Read 1869 times)

Posts: 9

« on: February 17, 2001, 06:28:57 PM »


I was wondering if anyone has an idea on stringing an antenna that will tune on 80-10 m.  My situation is as follows;  I have a small yard with no trees.  I can string a wire accross the top of the house and then (like a "L") into the back yard.  I would have to construct some sort of a cheap mast in the yard as there are no other tall supports.  Total flat-top lenght available is 40'+50'=90'.  To complicate matters, my house has aluminum siding.  I was thinking about a G5RV, but that is 120' and the G5RV Jr is reportedly only good on 40 m and above.  I already have a vert. antenna and I'm not real happy with it.

1)Any antenna ideas?
2) Any ideas on a cheap mast?

Thanks for any help!

Posts: 599

« Reply #1 on: February 17, 2001, 08:43:15 PM »

I'd start by using ladder line to feed a dipole about 40 feet or thereabouts  on each side. Make each side as long as you can but keep them the same length so that the antenna is balanced.  About five feet from each end, place some loading coils made by winding #12 or #14 wire on PVC pipe about 2 1/2 inches in diameter.  There are several programs that can give you coil dimensions.  The ARRL antenna handbook has a section on shortened antennas that should be helpful. The newer version of the handbook comes with a floppy disk that has a very good program for designing shortened antennas. The antenna handbook also has some plans for an "A-Frame" mast which should be fairly inexpensive. You'll need some sort of tuner for the antenna.  The efficiency will be compromised a bit on 80 but it should work well on the higher bands. Good luck!

Posts: 3585

« Reply #2 on: February 17, 2001, 08:56:32 PM »

  I think most all of us subdivision dwellers have that same problem. I have about the same amount of room you have, which makes me put up an L shaped dipole, sloping from the center support.
   I got out the post hole digger and went down about three feet, dropped a partly extended 30 foot TV "push up pole" in the hole, used clothesline as temporary guys, tamped bagged readymix concrete around the pole, watered it well, and the next morning I took the rope off and hung my antenna. And it's been up more than 10 years, through dozens of squall lines, thunderstorms, and one hurricane.
    As far as the antenna goes, you really have only a few viable choices. Trap dipoles, slopers, and Marconi's. My choice was a trap dipole. I put up an Alpha Delta DXCC, trimmed the outboard section to resonance at 3.8 mHz, and it's been up ever since. It's not the purists choice but I have both VK and SV on it so I guess I'm not a purist.
    Anyhoo, that works for me so that's my suggestion.
    73,  Pete Allen  AC5E

Posts: 2

« Reply #3 on: February 17, 2001, 09:00:29 PM »

Try using a single 80/40 meter trap and make a 1/4 wave inverted L.  Base feed with buried coax at the far end.  Use a lot of radials at the base.  A good mast is poles used for big birdhouses (Martin Houses) about 15 feet high. Run the wire from the base up to a standoff at mast top.  Keep wire at least 6 inches from mast.  Ground the mast. Run horizontal part to top of your house. Total wire length will be 58 foot approx. Vert 15 foot + Horiz 43 foot.  The single trap permits 80-10 coverage.  You will need a tuner on some bands.  I use this antenna and work the world on 100 watts easily. More radials the better.

Posts: 9

« Reply #4 on: February 17, 2001, 11:52:21 PM »

I could see procuring a Radio Shack thirty-six foot mast, and making a fundamental quarter-wave 80 meter inverted L, fed with 450 ohm ladder line to a current balun to a tuner.  Run the wire to top of mast at thirty-six feet, with a standoff as previously mentioned, and leave about 35 feet to complete the L.  Ply the ground with as many radials as possible, and you have an antenna that will get you on 80 and 40 with some low angle radiation, as well as 20, 15, and 10 with high angle radiation.

Posts: 4

« Reply #5 on: February 18, 2001, 01:39:36 AM »

I was in a very similar situation many years ago as a teenage ham with limited resources. I ended up putting up six foot poles on each end of the house and a forty foot mast in the backyard. I used three 20-foot 2x4's, two in parallel for the bottom half, and the third for the top half. They were overlapped about 3 feet and held together with carriage bolts. The whole thing was mounted on a six foot 2x6 set in the ground, and then pivoted to an upright position and guyed. It worked well for several years. It was in the ARRL handbook then(in the 1960's) and may still be.
For the antennas I used several bent dipoles. However since then I have experimented with many limited space configurations, and, knowing what I do now, would try 1)a windom(off center fed multiband dipole)fed with 300 ohm twin lead and a 4:1 balun; it's about 134 feet long and the ends could be bent as necessary... and 2)a full wave 40 meter horizontal loop fed with coax. (would not work for 80 meters, but the windom would). Of all the antennas I have tried in tight spaces, these performed the best for me. They are both multiband antennas which I used without a tuner, but that was with a rig having tube finals.
Good luck,
Larry, WA7O

Posts: 63


« Reply #6 on: February 18, 2001, 06:08:35 AM »

GE,OM! Good to see you on eham.You could try an 80m delta loop(triangular shaped). I am a big fan of loops and talk about them whenever possible. In a typical installation. put 1 corner high as possible on the house and the other 2 just high enough to be out of reach from the ground(remember to do the math for rf safety).Feed it with ladder line and a tuner and work 80-10m with no problem. The loop cut for 3.900 would be 85.9 ft. on each side, and this could be oriented along the long section of your property. Also, two 10 ft. masts at each corner should be OK, and at this height, 2.5" diameter or so pvc pipe should work fine.
Good luck and 73 de Matt, KF4ZGZ

Posts: 1071

« Reply #7 on: February 18, 2001, 09:03:17 AM »

My plot is 100 foot by 30 foot, so fitting a "80 to 10" antenna into it isn't too hard.

I've tried a coaxial fed 80/40 trap dipole (pair of traps resonated on 7 MHz), that is roughly 108 foot from end to end. These aerials were quite popular in the UK and had claims of working on 80/40/20/15/10, although they really only work on 80 and 40. Even with a W2AU balun, there was some interference to/from a shack computer.

My favourite antenna is a Doublet with a 100 foot top. This is fed with home made open wire feeder, about 25 foot long, connecting to a home made 4:1 balun on the outside wall of the shack. A short length of coax goes straight through the wall to an atu. The antenna works better than the trap dipole, no TVI or computer QRM, and tunes on most bands. You need to keep the open wire feeder tight, I use nylon garden strimmer line tied to one of the spreaders.

I have a 10 foot pole on the gable end of the house, fitted with a "yacht" pulley and a length of rot proof cord. This enables me to swap antennas with little difficulty and no climbing.


Posts: 21764

« Reply #8 on: February 19, 2001, 05:26:51 PM »

Everything mentioned sound like viable solutions.  But you said that you have a vertical and you're not very happy with it.  What's wrong?  What is it?  For DXing from a restricted lot, it's very difficult to beat a vertical -- although for "local" work they can work very poorly.  Using a roof-tripod mounted vertical with resonant radials, I work far more DX on the HF bands than any of my neighbors using wire antennas of any configuration.  Under average February 2001 conditions, I can call "CQ" on any of the bands and receive multiple answers from the Middle East, the Pac Rim, Europe -- pretty much anywhere -- using my vertical.  This isn't "chasing," it's more like "being chased."  So, every time I hear about "my vertical doesn't work," I'd like to know more.  But 'tis true for local work, Sweepstakes, traffic handling, stuff like that, I'd prefer a low, horizontal loop antenna of some sort.  Much better than a vertical for this kind of activity.  Remember, whatever you decide to install, any antenna will make contacts -- try to avoid those designs that require so much "tuning" (constant tweaking of an antenna tuner) that you spend all your time tuning and no time operating!  It's an easy trap to fall into.  Good luck & have fun!

Posts: 17476

« Reply #9 on: February 20, 2001, 06:18:30 PM »

I've used several "inverted L" antennas for 40 and 80, and they
work quite well.  (W6 to JA on 80m with 2 watts.)  If the total length
is around 65' you can use it on both bands with a home-made
matching network at the base (pretuned to match on both bands
without readjustment.)

With the configuration you described, you could start with a random
wire and a tuner.  You will probably want at least one quarter wave
radial for each band on the tuner as a counterpoise, but the wire
length should be long enough to radiate useful RF on all bands.

A full-wave loop for 40m would fit in the space you have described.
If feed with twinlead to a tuner, it could be pressed into service on
80m, but isn't optimum.  However, it should work well on the higher

Antenna supports:  TV mast is a good start.  If you find a piece of
pipe which fits over the bottom mast section, you can sink that
in some concrete (with gravel at the bottom, so it will drain) then
insert the TV mast into it.  This allows you to remove the mast,
and also lowers the push-up adjustment to a more reachable
height.  Always use a pulley on the mast, to make it easy to change
antennas.  If you can clamp the mast to the side of the house, it
may not need any guys, but you probably want it as far from the
house as possible to maximize the wire length.

Other possible mast materials are the galvanized pipe sections used
for top rails on chain link fences (cheaper than TV mast), large
diameter PVC or ABS pipe (typically available in 20' sections -
will require guying, perhaps at 2 levels), or sections of downspout.
A local garden supply store may have different lengths of bamboo
poles which could be nested.  Also, check out the military surplus
dealers to see if they have any of the mast sections used for
camouflage netting - typically in 4' lengths.  Heights up to 20' are
relatively easy to attain using simple wood masts:  a couple times
I've used a 12' length of 1x2 inserted into the vent pipe on the
roof.  (With a removable pin to keep the mast from slipping further
down in the vent, I had a cheap push-up mast.)  And, of course,
you can use combinations of materials, such as a 10' 2 x 4 board
with an 8' piece of aluminum tubing attached to the end, with a
bamboo pole stuck in the end of that....

Of course, some of us have to please the aesthetic consultants
living in the same house!

Posts: 9930

« Reply #10 on: March 21, 2009, 07:09:06 PM »

how about a nice sgc 237 and a long  wire in the tree, or  a fan dipole??

Posts: 7718

« Reply #11 on: March 21, 2009, 08:03:25 PM »

90' is long enough for a center fed (or thereabouts) 80-10 meter dipole. Feed it with ladder line (The Wireman has good ladder line with 544 being the best).

The tuner need not be fancy. A low cost MFJ-901B will tune such an antenna.

The short length will result in a rather high 80 meter VSWR on the ladder line but it will still work well. 40-10 meter efficiency will be high.  

If feeding at the center is awkward feed it as close as 30% from an end.

Posts: 2440

« Reply #12 on: March 21, 2009, 08:47:13 PM »

I'm willing to bet he doesn't remember what the question was after 8 years.

Posts: 1

« Reply #13 on: March 22, 2009, 07:59:29 AM »

Don't hams read catalogs anymore.  I see trap dipoles that are much shorter than full size, I see loaded dipoles that are short, I see loops, I see.............

Posts: 4311


« Reply #14 on: March 22, 2009, 01:08:51 PM »

> K9UNA wrote: I was wondering if anyone has an idea on stringing an antenna that will tune on 80-10 m. <

This is a similar problem to people who can erect an 80m dipole but not a 160m dipole. So, since antennas are scalable, the same solution should apply.

Erect a 66 foot 40m dipole and feed it with ladder-line for 40m-10m operation. For 80m operation, short the ladder-line conductors together and feed it against ground, Marconi-style. This turns the 40m dipole into an 80m vertical with a top hat and it works very well with a good radial system. If the height of the 40m dipole is about 30', the antenna will be near resonant on 80m.
73, Cecil, IEEE, OOTC,
"Government 'help' to business is just as disastrous as government persecution..." Ayn Rand

73, Cecil,
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