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Help with Monkey Made antenna

Discussion in 'CB Antennas' started by radiohobby, Jan 4, 2011.

  1. radiohobby

    radiohobby
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    Have a friend that bought one of those Monkey Made antennas with the big coil on it and the swr is crazy. It is about 2.1 on 40 and over 2.7 on ch 1. when on the roof using a big mag mount. When attached to the bracket on the bed rail it is over way into the red everywhere.



    Has a 4 or 5 foot fiberglass with adjustable metal tip and it has only the tiniest bit of movement on the swr meter at either location. I mean if you don't look real close you can't even see the needle move off the black line for 1:1, its that good.

    Anyone ever used one of those Monkey things got any ideas how he can get it tuned? Could they have sold him one made for 10M? He bought it when he bought his General Lee. They told him the radio would be tuned and some mods that he bought would be installed. When he received the radio the mods were not installed and it had not been tuned. The antenna came without the top metal rod section. They finally sent him that part. He had been using the fiberglass one which like I say has a fantastic swr reading.

    As an example of how well the fiberglass one works on the bracket he has on the truck bed we talked when he was heading home until he was over 23 miles away as the crow flies. I have just a sirio dipole mounted with feed point at 20 feet mount for vertical signal and using old style cobra 148gtl.

    Anyway I guess he was hoping to use that other one and maybe get better range. After we tried several things to get the swr down and he saw how well the fiberglass worked he decided to try and get them to take the other one back and they refused saying that he had a ground plane problem. It seems to me having it mounted on the roof of a fourdoor pickup would give it a pretty good ground plane and mounted on the bedrail was worse.

    Also don't forget the fiberglass one has almost a perfect swr reading and talks great. He just wants to know if there is anything we can do to get the Monkey made to work.

    If the metal rod that goes in the top is too short I think that would cause what we are seeing I think but with no experience with that kind of antenna would like to see if anyone has any other ideas. Thanks for any help anyone might have.
     

  2. Robb

    Robb
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    Check the SWR on the "E" band; 27.405 - ~27.800mhz. If the Monkeymade gets the right SWR on that band - it means the antenna is too short for the CB/40 ch band. You should lengthen the tip by adjusting it upwards until it is reading correctly on the SWR meter for the regular CB/40 ch band. They are adjustable - or should be . . .

    Pity about the tune-up job.
    Who did he buy it from?
     
    #2 Robb, Jan 4, 2011
    Last edited: Jan 4, 2011
  3. AudioShockwav

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    Is there any adjustment that can be made on the whip?
    If you can loosen the set screw(s) and raise the whip up until it is as long as you can while still having enough to get the set screw to still hold the whip securely it should lower the SWR.
    I agree with you, it seems the whip they sent is too short.


    73
    Jeff
     
  4. radiohobby

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    Thanks for all the help guys. I had ordered a replacement K-40 whip, large bird hit antenna going down the highway, and it came in shortly after I posted this.

    I went and picked up the whip and went over to his house and decided to try some things since I wasn't convinced he had done the first checks correctly after talking to him again. I took my new whip and used zip ties to attach it to his whip to make it longer by a couple of inches.

    Took some reading and it was into the red zone big time. Had him push the add-on down some and took another reading and guess what, it got better. Kept doing this until it was flush with what he had and it got better each time. So I asked him some more queations and it turns out that what he had done before wasn't exactly what I had thougth he had done.

    Put the k-40 whip into it instead of his since the k-40 was about half inch shorter and it got better still. chopped off 1 inch from his a quarter inch at a time before he was called into the house for supper and it was down to 1.9:1 at that point. Left my hacksaw with him and said have fun and be careful.

    He doesn't want me to say who he bought the radio from. When he put it in his truck they kept telling him that couldn't hear him but he had a strong signal. Put it on the meter and dead key was way up and it only managed to get about 60 percent modulation with tone injected into the microphone.

    After retuning it lowered the dead key and now get more swing and 95 percent modulation with the tone injection. And now sometimes they tell him to turn the mic down when he is close by.

    Anyway looks like with a lot of chopping he will get it going. Just goes to show you that it is best to forget what you have been told and do some of your own checks prior to doing anything that can change things. And it helps to have some spare antenna parts laying arouond. That k-40 whip sure helped to show what really needed to be done.

    Thanks again guys for the feedback.
     
  5. triple nickel

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    When ordering the monkey Made or Bronco Buster ( Round Coil ) the whip that comes with it is bigger round in diameter than a K-40 whip, And a lot stronger. From the get go he should of had good SWR. Sounds like the CB Shop sent him a short one. The whips come in 3 different lengths. IMO i would reorder a longer whip. I would ask for the longest whip they carry for the Monkey Made. That way you could always trim down a little. Also you quoted this was mounted on a mag mount ?? I have mine mounted on a Tram Tri Mag mount. The 3 magnets are 5" in diameter. Hope this helps.
     
  6. radiohobby

    radiohobby
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    Yeah the k-40 is a lot thinner than his is. I just attached it to his with zip ties so that it became part of his so I could make it longer and shorter to really see what we needed to do to get his right. By sliding it up and down we could change the length and that made it clear that we needed to make his shorter. After cutting it down to size it now has good swr and better signal than the fiberglass one he was using.

    He is using that same triple mag mount.

    Thanks to everyone that helped out.
     
  7. GnG8d

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    For future reference, you can use the band selector to get you into the ballpark, then use the channel selector for final adjustments.
     
  8. radiohobby

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    That is good to know 359. His was the first radio of that type that I have ever had the pleasure of working on. I used this site to get all the info I could dig up before I agreed to help him by tuning it. After checking on here for all that I could find and putting it on my bench it looked to me that all they did was turn the carrier way up and call that a tune.

    Hadn't even thought about that band switch, not used to having that as an option. Electronics technician from way back but working primarily on automotive systems for quite a few years now. Had to dig all my radio and repair equipment out of my storage shed to work on his radio and got me back into my favorite hobby again.

    Guess I have gotten a little rusty but it is coming back to me and sure have been having fun again. Gonna have to dig up all my old notes and books because I think I am going to try and get back into doing more of this type of work and less of the auto work.

    I have doing lots of reading here and everywhere I can to get up to speed on more of todays modern radios. When I was doing this business before tubes were still in use for the top of the line equipment and the 148gtl stuff was just getting started good. Then I went into the computer field for lots of years and then into the automobile field since they are so computer controlled these days but they aren't as much fun to work on as they were a few years back. Getting things to crammed into too little a space.

    Thanks for the tip, I am always open to learing new things.
     
  9. DJboutit

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    I have heard from a few people in the past who use to run monkey made they could never get the swr under 1.3 so they switched to another antenna. If you do get the swr down to 1.3 just leave it a lone
     
  10. radiohobby

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    Yeah that is where we stopped at ourselves. That thing talks about as good as the old 102 whip.
     
  11. HomerBB

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    Just as a note FYI, I always use a piece of wire to tune antennas with instead if the whip/stinger. Sometimes a wire clothes hanger straightened out will do. Cutting the wire when going shorter prevents mistakes to the stinger sent with the antenna. Once the length I need is found on the wire, I cut the stinger to that length and put it in the antenna. If the stinger is significantly thicker than the wire I used it may need to go a little shorter a little at a time until satisfied. Once the stinger has been trimmed into the range of the CB 40 channels, 26.965 - 27.405, you will know what to do with the stinger.

    When cutting your stinger always cut it so it can rest into the bottom of its nesting hole in the shaft of your antenna. You'll be able to raise it back up a little in this case if needed.

    I have even used a piece of thick copper ground wire for doing this.
     
  12. GnG8d

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    That's a good idea. I've bent a few stingers, and I straighten them out and keep them for spares/tuning.
     

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