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Author Topic: home brew fiberglass whip for 11 meter  (Read 2510 times)
ASANDBERG6
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Posts: 8




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« on: July 29, 2012, 08:58:55 PM »

I followed the quoted instructions here to build an antenna using a 9' ATV flag pole. My question is, to mount it to a wood builing with ground plane do I need anything else, such as radials or something? I'm a complete noob that couldn't break into HAM, and now have a CB to play locally with. Please speak loud and slow as I am a radio tard, and thank you for any advice.

Quote
Fishing Pole Ear--A Homemade Mobile CB Antenna

While the next project won't necessarily save you any money, you might want to give it a try if you are interested in understanding more about how fiberglass whip antennas do their thing. We have talked 30 miles mobile-to-base on one of these home brew fishing pole antennas using a $20 barefoot rig.

 
Antenna Parts

    One 7-foot fiberglass fishing pole with hollow base One piece of steel rod 4 to 6 inches long-right diameter to slip into base of pole One ¼" x 1" machine bolt (threads to match mount) 12 feet of enamel #18 gauge wire Some good epoxy glue


 
Antenna Mount Parts

    One 114' x 21/z" bolt and nut (same threads as bolt on base)

    One longer-than-usual ¼" nut

    Two plastic insulating washers

    Three metal 5/8" diameter washers

    One large terminal lug


First you've got to get yourself a fishing pole, 6 to 9 feet long. If you already have an old one lying around, you can clip off the line loops and cut the handle off.

We did some shopping and found that a finished fishing pole as long as we wanted was at least as expensive as a newly-manufactured CB antenna. But then we discovered a sporting goods store that sold unfinished fiberglass poles 7-feet long for $6. The kind we found was a black hollow tapered pole with about a 1/8" inside diameter at the base.

The next step is to hook something to the pole so you can screw it to a mount on your vehicle. The way we did it was to get a piece of scrap steel rod near the inside of the base of the hollow pole. (If the pole is not hollow you will have to figure out another way of hooking to it.)

Grind a slight taper to match inside taper of the fishing pole. Braze bolt to rod. Use 1/4" x 1" steel bolt. Epoxy the steel rod inside the base of the fishing pole.

There are many commercially made CB antenna mounts that you can buy at electronic parts stores that could be used to hold your fishing pole ear. If you elect to buy one of these mounts, get one with a spring so that if the pole encounters a stray tree branch, it can bend instead of break! If you are going to use this antenna with a store bought mount, the threads on the bolt on the bottom of the antenna should mate with the hole in the top of the mount's spring.

 
Tuning the Fishing Pole Ear

Now it's time to get into the electrical part of the antenna. The fishing pole is not the antenna; it's just a prop that holds the wire up. So we need to wind a wire around the fishing pole in such a way that will make it tune the 27 MHz CB band

If your antenna is shorter than 9 feet long, you can tune it by winding a coil around the pole. On our 7-foot ear, we found that it was necessary to make a coil of four turns ¼" apart about 2'- 3' up from the base of the pole. Tightly wrap the wire in a spiral up from the base of the pole. Make the distance between windings as wide as possible below and above the coil. If you follow these particular dimensions you should be close to being tuned up. To really make the ear a perfect match, however, you'll need to use an SWR meter to check the SWR. You may have to modify the coil spacings or add or subtract a turn from the coil to get it just right.

Different lengths of CB Antennas will also work, but different coil windings will be necessary, so if you have a different length pole you'll have to use a meter to tune it up. You just have to dive right in and try different numbers of coil windings. The longer the pole, the less center coil windings; the shorter, the more windings necessary. It takes some playing around and trial and error.

We used enamel coated wire, the kind used in motor windings, generators, transformers, etc. It's best to use enamel-coated wire so that the coil turns can't possibly short to each other.

At the bottom, wrap the wire around the 1/4" bolt. Be sure to scrape the enamel coating off the wire and clean the bolt for good contact. Solder that wire to the bolt or use a nut to hold the wire onto the bolt so that it makes a good electrical connection.

We covered some CB antennas we made with a thin coat of fiberglass (which you can tint any color you want). They looked pretty good but the fiberglass chipped off some of the antenna tips because they were mounted fairly high up and got tangled in the trees. You can prevent chipping by putting some shrink tubing over the tip. Shrink tubing would be another possible way to hold the wire on the fishing pole. It's available at most electronics shops.
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WB6BYU
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« Reply #1 on: July 29, 2012, 09:10:23 PM »

Yes, you will need radials to form your ground plane.  Cut two wires to about 9' each
and connect one end of each to one of the mounting bolts for your antenna base (not
the antenna itself.)  You can use 3 or 4 wires if you want.  You can use just about any
sort of wire for this.  String the wires out in as much of a symmetric pattern around the
base of the antenna as possible.  Sloping them downwards at an angle will improve the
SWR, but it will work if they are flat.
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ASANDBERG6
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« Reply #2 on: July 29, 2012, 10:55:55 PM »

Thank you so much. I imagine coat hanger should work for this? It would be nice and rigid.
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G0VKT
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Posts: 64




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« Reply #3 on: July 30, 2012, 06:16:37 AM »

You must have big coathangers to get 9' of wire out of one. Grin

Use flxible wires and guy them. Use three of four symetrically round the base. As said, angling them down 45 degrees will improve the match to the coax.

If you can get it to work then ham radio is not beyond you. Building antennas can get a bit addictive.
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ASANDBERG6
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« Reply #4 on: July 30, 2012, 07:02:02 AM »

Yeah I noticed that last night as I was going to bed. Initially I thought it was 9".been a long time since I lurked here trying to learn everything radio I could.
I haven't given up on Ham altogether I just had to sell the radios to pay bills and really don't have room at this rental for an antenna.
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ASANDBERG6
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« Reply #5 on: July 30, 2012, 02:35:40 PM »

OK I have a north facing peak on the roof of my garage. Could I run a SW an SE radial down the two slopes of my roof, with a north facing radial  down to my backyard fence? Or would the roof represent to much of an obstruction? I guess I'm asking do the radials have to vertically clear all obstructions? Sorry for the noob questions but I'll get back into studying all this real soon.
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WB6BYU
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« Reply #6 on: July 30, 2012, 03:21:34 PM »

Actually that's the kind of practical question that doesn't appear on the test, or
in a lot of references.  A lot of theoretical discussion about antennas takes place
in "free space", which is not often a good description of where we are trying to
install them, particularly on HF.

Yes, you can lay them on the roof and run one down to the back fence.
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KI4SDY
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« Reply #7 on: July 30, 2012, 07:40:24 PM »

You fellows do realize that this posting is a hoax by a prankster don't you?  Wink 
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ASANDBERG6
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Posts: 8




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« Reply #8 on: July 31, 2012, 07:06:09 AM »


Yes, you can lay them on the roof and run one down to the back fence.
Thank you.
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ASANDBERG6
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« Reply #9 on: July 31, 2012, 07:12:49 AM »

You fellows do realize that this posting is a hoax by a prankster don't you?  Wink 
Why, because I want to be a CBer? Or because I'm asking how to set up a base antenna? I have better things to do than prank on the internet. And I wouldn't be pranking hams.
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K5KNE
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« Reply #10 on: August 01, 2012, 07:42:33 AM »

If you will send me an email at "k5kne@swbell.net" I will be glad to answer all of your questions about how to make a good antenna.

Walter  K5KNE
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KI4SDY
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Posts: 1452




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« Reply #11 on: August 01, 2012, 07:51:03 AM »

My apologies. Your right! No one would waste their time trying to pull a prank on hams because they are too smart to fall for it.  Wink
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ASANDBERG6
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« Reply #12 on: August 01, 2012, 12:07:00 PM »

My apologies. Your right! No one would waste their time trying to pull a prank on hams because they are too smart to fall for it.  Wink
I dont doubt that there are gullible hams, but there are more deserving groups on the internet, such as Honda tuners (fast &furious).
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KI4SDY
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« Reply #13 on: August 02, 2012, 07:32:54 AM »

"I don't doubt that there are gullible hams,"
I can attest that you have taken advantage of that!  Grin

"but there are more deserving groups on the internet,"
I am looking forward to your migration back the flock!  Roll Eyes
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