Cheap and Dirty CB Base Antenna you can build in an hour

Discussion in 'Survival Communications' started by BTPost, Aug 23, 2011.


  1. BTPost

    BTPost Old Fart Snow Monkey Moderator

    This is a cheap and dirty CB Base antenna that you can build in an Hour, out of stuff you have laying round.

    Parts:
    50 ft of 50 Ohm Coax... any size.
    20 foot piece of 1" PVC Pipe with one End Cap
    Little bit of PVC Glue
    One PL-259 coax connector
    Roll of electrical tape
    Tube of Epoxy glue

    Instructions:
    Take your coax and measure 108" from one end, and then carefully cut the outer covering and strip it off so that you have 108" of braid showing.
    Then carefully pull the braid down at the 108" point and using a knife or pair of scissors, but the braid 1/2" above the 108" point and remove the braid tube from the insulated center wire.
    Fold the .5" section of braid left, back down over the outside insulation, and then wrap it with some small cooper wire, and solder the copper wire to hold the braid in place.
    Now take the Braid Tube and slide it over the other end of the coax, until it is up to the soldered section you just made, and then solder the end of the Braid tube to that section.
    Pull the Braid Tube down the coax, using the free end, until it is stretched tight. it will be approximately 108 In long, and use some Electrical Tape to secure it to the coax.
    Push the Center Insulated Wire end of the coax, up inside the PVC Pipe until the end comes out the far end. Take the PVC Cap and fill it 1/2 way full of Epoxy Glue, and then stick the end of the Center Insulated Wire, in it and let it set up solid.
    Coat the end of the PVC Pipe, with PVC Glue and push the Cap with the Center Insulated Wire embedded, on to the Pipe end and let that setup.
    Take the electrical Tape and use it so seal up the other end of the PVC Pipe where the coax is hanging out.
    Install the PL-259 coax connector on the far end of the coax.

    Plug the Pl-259 into your CB Radio Antenna Connector, (SO-239) and mount the 20ft PVC Pipe Vertical, at the bottom, and start talking.

    You have just built a Vertical CB Dipole Antenna, that needs NO Grounding, or other constructs, to work. The RF Ground is made, using the Braid you threaded back over the free coax end, and soldered to the center soldered Section.

    ...... YMMV.....
     
    Tully Mars, GOG, Idahoser and 4 others like this.
  2. Cephus

    Cephus Monkey+++ Founding Member

    Sounds like it could be hung anyplace and used to beef up the out put on a hand held that has a pigtail.
    Great Idea!!
     
  3. BTPost

    BTPost Old Fart Snow Monkey Moderator

    Yep, and if you seal up the coax itself, you can do away with the PVC ad just hang it from a high tree limb.....
     
    Cephus likes this.
  4. Cephus

    Cephus Monkey+++ Founding Member

    A movable fast set up dye pole antenna to increase range ,I like it a lot . Move and scoot after message sent. GREAT IDEA!
     
  5. dwf4475

    dwf4475 Monkey+


    "Move and scoot" sounds like a pretty good idea for SOP.

    One modern DF equipped unit can find you very quickly, 2 will find you instantly. Then ARTY will soon be raining down on that position.

    That could make for a very bad day. :oops:





    ---
     
  6. Tikka

    Tikka Monkey+++

    This one is easy to build.

    [​IMG]

    CB is from 26.965 to 27.405; 27.185 is the middle of band. Swap the 28.450 for 27.185.

    The .66 is the velocity factor: Coaxial cable velocity factor information The easiest coax cables to buy are RG8, RG56, RG213, RG214 they are all .66. The exceptions are RG59 at .82 and RG8X at .84.

    This one and the J pole I posted earlier are both omnidirectional with no lobes; when viewed from the side both have a low angle lobe.
    Jpole vs. Coaxial Dipole EZNEC Shootout | Ham Radio Help Desk

    Same as all rehabilitated DX'ers I'm still an antenna junkie. :D
     
    Last edited by a moderator: Feb 5, 2015
    3M-TA3 and BTPost like this.
  7. allansplace

    allansplace Neophyte Monkey

    Great post!
    I know it was six years ago, but I'm hoping you'll answer one question. Or anyone who views this page and knows.
    Does this bottom 9' of this have to be above buildings or anything that blocks the signal? Or can the ONLY the top 108" poke above the roof line of a house? I think neighbours will question 20' of PVC sticking up, but hopefully they won't notice 10'.
    Thanks for the instruction!
     
  8. Merkun

    Merkun furious dreamer

    Just the top 108 should be clear of obstructions, but higher is better. In fact, you can hang this from a window and it'll still work, just not as well as if higher.
     
  9. BTPost

    BTPost Old Fart Snow Monkey Moderator

    The bottom half is the Groundplane... (Counterpoise) For the driven element, which is the Top 108"...
     
  10. Idahoser

    Idahoser Monkey+++ Founding Member

    quick and dirty antenna...
    measure a quarter wavelength of cable (whatever wavelength you want to use) and pull the center conductor out of the side of the braid from that point on the cable.

    That's it. You now have a half wave dipole. Center conductor one way, braid the other.

    Hang it vertical or horizontal.

    Found this and thought it worth a share
    Field Expedient Antenna Systems | AMRRON
     
    Last edited: Jun 22, 2017
    Homer Simpson likes this.
  11. allansplace

    allansplace Neophyte Monkey

    Thanks for the reply!
    I have one further question, if you don't mind.
    Background: I cut the end off a 50' cable and cut 108" of outer plastic casing off. I folded back inside-out 108" of braiding downward over top of the remaining cable. Now it is double-insulated with shielding. I hope this will work.
    My question is, what do I do with the remaining thin shielding and white plastic casing that covers 108" of coax core cable? I have to expose that inner core cable, yes? That would be the last pic here.
    I hope I can upload pics here.
    Thanks everybody for all this cool help!
    Allan

    DIY HAM antenna 20170627_234644 cut off one end small.

    DIY HAM antenna 20170627_234737 cut along insulation (NOT braided shield) small.

    DIY HAM antenna 20170628_000025_001 rolled braided shield backward over insulation small.

    DIY HAM antenna 20170628_000109 taped end of braided shield small.

    DIY HAM antenna 20170628_000153  foil over poly insulator and conductor small.
     
    Last edited: Jun 28, 2017
  12. BTPost

    BTPost Old Fart Snow Monkey Moderator

    You have to strip the Foil off the inner Conductor & Poly Insulator..... that foil is part OF the Shield/Braid, and needs to be gone... What you want for the Top 108" is just the poly Insulation with the center conductor imbedded in it's core....
     
  13. allansplace

    allansplace Neophyte Monkey

    The last step - I'm on it. Thanks!!!
     
  14. Merkun

    Merkun furious dreamer

    Yup, the foil must go. The poly will have essentially no effect, and in fact should help with strength in however minor a way. You MUST seal the end against water entry as well as where the braid is folded back. Let us know how well it works.
     
  15. allansplace

    allansplace Neophyte Monkey

    Update: My radio's build-in SWR says "SWR HI", beeps, and stops broadcasting. I trimmed both ends to 102 inches, pulled the center core through a gap in the braiding, moved the antenna around inside & out, used different power supplies, and nothing will get my SWR anything close to what the radio wants. I think I failed somehow. Not sure how. Faulty cable ordered online maybe? Should be OK. It's from MPD Digital, made in the U S of A. So is the radio. Really picky radio? Unsure at this point. Will grounding the radio affect the SWR? Any suggestions?
     
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