Cutting an 11 meter Firestik antenna for 2 meters

Discussion in 'Mobile Radio' started by WR0H, Jun 30, 2015.

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  1. WR0H

    WR0H XML Subscriber QRZ Page

    I am an over-the-road truck driver and have been a licensed ham since 1971. I want to use 2 meters in the truck but my antenna choices are limited since my truck belongs to the company I drive for.

    I have a 4 foot long Firestik CB antenna that I would like to cut down to a quarter wave on 2 meters. It's a simple fiberglass rod with a wire wound around the outside, covered with a PVC coating. While it's not an optimum performer, a quarter wave is fine for my purposes, I just need to know where to saw the antenna off. Do I cut it where the total (unwrapped) length of wire is 19", or where the rod is 19" regardless of how much wire is wound around it to that point?
     
  2. WR0H

    WR0H XML Subscriber QRZ Page

    Being the impatient/inquisitive type, I put it in the vise, measured up 15" from the bottom (the 2M Firestik is 15" long) and sawed it off with a hacksaw. Connected it to my Kenwood and I'm hitting repeaters all over. Good enough.
     
    KK4CCA likes this.
  3. KO6WB

    KO6WB Premium Subscriber QRZ Page

    There you go!!!!!!

    A little inventiveness goes a long way when you want to get it done.
    Likely that would have been the advice you'd have been given except, you would have been told to cut it at 19 inches and cut it down from that point.

    BTW welcome to QRZ and have fun with amateur radio.

    73
    Gary
     
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  4. K4KWH

    K4KWH Guest

    Good for you! Its how we learn our hobby and reap the rewards of our curiosity and inventiveness. Heck, I probably burned up more radios and stuff than anyone on here. But its how I learned, "don't do dat no more; it doesn't work"!:p Glad it worked for you. I would, however, to be on the safe side, check the swr..........just in case. Repeaters are funny. If you can 'hit' repeaters from a long way off, it just may mean it's super sensitive, is at a high elevation. Like Mt. Mitchell, NC at 6600 feet. Your SWR could still be WAY off, and one day....POP! There goes your final.:(
    It never hurts to check!;)
     
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  5. KC8HEF

    KC8HEF Ham Member QRZ Page

    1 was just wondering what the swr was?
     
  6. WB2WIK

    WB2WIK Platinum Subscriber Platinum Subscriber QRZ Page

    I evaluated a few Firestiks years ago and they were almost the worst CB antennas I've ever tested. No kidding.

    Truly lousy designs; the wire wasn't even pure copper and had measurable resistance from one end to the other. I wonder what they actually were, but copper coated stainless steel might be...however if the copper really was intact, the resistance should have been about zero, and it never was in any of the three antennas I measured.

    The 'Firestik' magnetic mounts were worse. Zero electrical connection between the feedline outer conductor and the bottom of the magnets. I could hardly believe that, but confirmed it three times. What they did was connect the outer conductor of the coax to a stud at the top of the magnet; that looks cool, except magnets aren't electrically conductive and the resistance from the coax outer conductor to the bottom of the magnet, where it would attach to a vehicle, was almost infinity...in three of them.

    Worst design I've ever seen.
     
    KK4CCA likes this.
  7. KA9JLM

    KA9JLM Ham Member QRZ Page

    I think those were one of the first Dummy Load on a Stick designs.

    Looked good on a SWR meter.
     
  8. WB2WIK

    WB2WIK Platinum Subscriber Platinum Subscriber QRZ Page

    Larsen got it right, so did some of the Wilson models.
     
  9. W5WRB

    W5WRB Ham Member QRZ Page

    I also bought a 10/11 m whip which came with a "cutting chart." Instructions stated: "Measure from Tip of Whip Down & Cut to Length." Length is determined by the distance between two points, one of which was the "tip." But, where is the other point? Is it where the whip enters the bottom mount where the set screws are? Or does the length also include the length (height) (c. 15/16") of the mount on top of the coil section? Or does it include also the mount and the height (3 5/16") of the coil section. The coil base is configured as a NMO mount. To summarize: what I am asking is does the "cut length" run from the tip to the top of the mount, to the bottom of the mount, or to the bottom of the coil? Would appreciate any insight! Tnx.
     
  10. KG7ZXA

    KG7ZXA Ham Member QRZ Page

    On both my Wilson and K40, I cut from the tip to the bottom of the whip ... except I added 1/2" to their number ... then checked swr, easier to cut a litter bit more off, than try to add back on!
     
    W6MYT likes this.

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