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Portable antenna for cb

Discussion in 'CB Antennas' started by xm49north7, Jan 25, 2020.

  1. 2NC995

    2NC995 DAN

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    Mine wouldn’t be for true portable/QRP operation...so it’ll be run with two truck batteries and a 190 amp alternator :) That could change...


     
    xm49north7 likes this.

  2. xm49north7

    xm49north7 Well-Known Member

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    Going to roll my own power pack. ordered 2 of these battery boxes off ebay for $2.75 each, will load with my own 18650 batteries which I buy wholesale through my business, Will wire these up with custom outputs and will run them either solo or together depending on how long I wish to operate. I will post in the forum when I get this built and tested in the field. I have access to quality 3500 mah batteries, I do not trust the stuff I see for sale pre-built, as most use very low quality batteries, and most cannot be replaced. If I build it myself, I can make it top quality for about 1/10th the price. If I build it, I can fix it!
     

    Attached Files:

    Shadetree Mechanic and 2NC995 like this.
  3. sunbulls

    sunbulls Sr. Member

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    Forget the $20 batteries found in hallway emergency lights and other places, those are sealed lead acid. Other than “initial cost”, Lithium wins out in every category. To name a few, they have a 6-10 times longer life span, they’re half the weight, better at handling temperature extremes, and charge 4-6 times faster. Lithium is the new wave and is constantly being improved upon. All the old school emergency lead acid lights are being phased out in favor of Lithium /LED combos. If you want a U.S. made battery, Dakota Lithium is one of the few manufactures.

    Also when going portable, don't forget to disconnect any incandescent bulbs in your radio. I installed a momentary push button on one of my rigs for that purpose. Using headphones or ear buds for a lower volume level also helps conserve energy. Every little bit helps when you're trying to swing around the moon and back.
     
  4. Mudfoot

    Mudfoot Elmer

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    I've been wanting to do this. Just get discouraged trying to find a good economical brand/model brand.
     
  5. WECSOG

    WECSOG Well-Known Member

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    I have a vertical(ish) dipole similar to that at my campsite, thrown over a tree limb.
    For portable QRP power I use a 7ah gell cell like this one: https://amzn.to/2GquvuH
    I do have and sometimes play with 18650 and other sizes of LI batteries, but to me they are neither as reliable nor easy to use as an old school lead acid (gelled, AGM or in larger sizes, flooded) battery.
     
    xm49north7 likes this.
  6. Marconi

    Marconi Usually if I can hear em' I can talk to em'.

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    xm49north7, I want to encourage you to continue with your modeling. (y)

    I really like you presentation. Was this image produced by MMANA-GAL?
     
    #21 Marconi, Jan 27, 2020
    Last edited: Jan 27, 2020
    xm49north7 likes this.
  7. xm49north7

    xm49north7 Well-Known Member

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    Thank you. I am really enjoying antenna modelling. The plots came from the software, the rest I drew up in photofiltre a free paint software, I like to get all the info on one page. I have had some fun with the modelling software made a really strange loop the other day, it looks awful, it was just an experiment the numbers were amazing but it is so ugly I am not sure it would work, or that I could stand it in my yard Laughs, but the software says it would have some serious gain. Sometimes I just like to see what the software can do. Great fun, highly recomend mmana-gal, I did not even read the help files, was able to figure it out after a few days of playing, found it very easy to use, there are a few vids of dxcommander using it on youtube, after watching those , I was on my way.
     
    #22 xm49north7, Jan 27, 2020
    Last edited: Jan 27, 2020
  8. xm49north7

    xm49north7 Well-Known Member

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    Antenna was tested today, tuned to a near perfect swr on second try. Tested it on 38 lsb, I put the 18 foot fish pole on a 6 foot wood pole, so height to the top was 24 feet, My buddy was in his truck we did 20 miles before contact went to zero. I am very happy with the performance of this simple antenna. I look forward to doing some hill top man pack radio this spring. Ordered some parts to build the battery pack, will be using 18650 batteries and will roll my own pack.
     
    Riverman likes this.
  9. xm49north7

    xm49north7 Well-Known Member

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    Here is my experimental loop North 7 experimental loop.jpg
     
    Marconi likes this.
  10. xm49north7

    xm49north7 Well-Known Member

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    This is pretty close to the antenna I run my base on. So far it is my favorite antenna. it is roughly 12 feet tall by 7 feet wide, hangs on a wood pole. 36 feet to the feed. my main antenna jpeg.jpg
     
    Marconi likes this.
  11. xm49north7

    xm49north7 Well-Known Member

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    I have the swr down to about 1.4 across all channels, just by tuning and coax arrangements. I really need an antenna analyzer, so I can get things done a little easier.
     
    Shadetree Mechanic likes this.
  12. Rick330man

    Rick330man WDX 404

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    Heck, if you're going to use a 102" and keep it simple...here's what I actually use here in the Keys when I go out to some nearby islands and want to communicate with the house or shoot skip.

    3 pieces: (1) a 102" section of 3/4" aluminum stock, (2) a mobile antenna bracket (see BJ radionut's diagram above) and (3) a 102" stainless steel whip. It is just a 1/4 wave dipole. My SWRs are around 1.59 at channel 1, 1.55 through the middle of the CB band and about 1.62 at channel 40.

    It is easy to set up quickly and delivers very respectable performance. Using a barefoot, completely untweaked Cherokee AH100 SSB walkie talkie, 20 miles local can be had on AM pretty consistently. When conditions are rolling, the skip with this set up is non-stop.
     
  13. xm49north7

    xm49north7 Well-Known Member

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    hard to roll up and put in my backpack, yes a 1/4 wave ground plane will do the trick for sure. The birds mouth is just a simplified wire version for portable. That was the whole idea. It just has one angled radial for the ground plane, which as the drawing shows is all you need, it gets out a little better off the side of the radial. 3 radials makes it a perfect omni. Dropping the one leg to a 45 degree angle, drops the swr, it is also 15 cm (6 inchs) shorter.
     
  14. BJ radionut

    BJ radionut Supporting Member and 6m addict

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  15. BJ radionut

    BJ radionut Supporting Member and 6m addict

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    xm49north7 likes this.

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