Multiple Antenna

Discussion in 'Antennas, Feedlines, Towers & Rotors' started by WX4PTO, Apr 15, 2018.

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  1. WX4PTO

    WX4PTO QRZ Member QRZ Page

    Greetings guys. New to ham world, little bit of frs play as a younger. Starting to get more and more into it. Currently use MURS, GMRS and CB (save the comments, I'm a trucker).

    Gonna set up a tower at home. Was looking around and saw "Slim Jim" antennas.

    Currently in process of buying a icom-4100. Have a Baofeng uv5r, and cobra 29lcd (again.. save it). My local REACT team also wants to put GMRS repeater up.

    Tower will be about 75' (hey, it was free, plus a few mods to add height)

    Now to the question. I understand the icom will need a dual band antenna, and prepared for that. But can I mount a 2m, 11m, and 70cm antenna on same plane, if so how far apart. Ideally I'd like to have all 3 antennas on the one tower.
    AND what's your views on Slim Jim's (I found them thru QRZ)
     
  2. WB2WIK

    WB2WIK Premium Subscriber QRZ Page

    I would not bother with a "Slim Jim," especially for a tower where it will be exposed to weather including high winds; you want something much stronger for an outdoor tower installation.

    For what you describe, you really don't need three antennas, just two: a 2m/70cm dual band antenna, and an 11m antenna. They can be mounted side-by-side using a crossbar brace, but I'd put them about nine feet apart to allow them to both work pretty well. Such a crossbrace with vertical pipes for mounting the antennas is available commercially, but of course can be made by any local welding shop.
     
  3. N5AVF

    N5AVF Premium Subscriber QRZ Page

    CB was one facet of radio back in the 70's that got me interested in SWL and amateur radio. No comments. That said, you might want to read over 47 CFR 95.408 (CB Rule 8). PDF Link: http://tinyurl.com/yc7nkk7a

    11m antenna height is limited to 60ft. (Highest point) Now, that's the rule, but you probably have a better chance of winning the lottery than having the FCC show up on your doorstep and enforce the rule. ;) Still though, good to be in compliance. Also, check local regulations about towers, permitting, etc..

    Pick up a copy of Up the Tower from the ARRL or Amazon. Many places out there to buy it. Excellent information for those new to installing & maintaining a tower.

    Good info here too: http://k7nv.com/notebook/topics/TowerTips.pdf
     
    NH7RO and WX4PTO like this.
  4. WX4PTO

    WX4PTO QRZ Member QRZ Page

    Unfortunately, I'd have to have 3 antennas, 1 for repeater, 1 for my base unit, and 1 for cb
     
  5. AA7QQ

    AA7QQ Ham Member QRZ Page

    I would put the CB antenna on the top. (Guessing a vertical) Put the GMRS antenna either 1/2 or 1/4 wavelengths multiples (Inject superior knowledge from Steve here) from the tower (Using tower as a quasi reflector)
    Then, a standoff for the dual band antenna, at the same height as the CB antenna. Distance from CB antenna TBD

    Ed
     
    NH7RO likes this.
  6. WX4PTO

    WX4PTO QRZ Member QRZ Page

    doesnt a quasi-reflector make it directional??????? (speak easy, rookie here)

    if so, id have to do at least 2 antennas. and if so, where would i position. sorry, doin alot of google research to figure this out.

    and yea, id need to know the distance between dual band & Cb antenna.....
     
  7. AC0GT

    AC0GT Ham Member QRZ Page

    FYI, The rules on Part 95 were revised last year, Section 95.408 no longer exists. Height limits are now listed under 95.941
    https://www.law.cornell.edu/cfr/text/47/95.941

    Doesn't look like the height rules changed, just listed under a new section. There were some material changes to both CB and GMRS, some more noteworthy than others. One example, the 155 mile communications limit for CB is gone. I believe power output limits for FRS and GMRS changed too.
     

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