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Coax recommendations

Discussion in 'On the Road' started by K6HAG, Mar 3, 2019.

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  1. K6HAG

    K6HAG Ham Member QRZ Page

    I'm a new HAM but experienced in radio and all tech and electrical having owned an electrical contracting company for decades. We used UHF business radios until cell phones arrived. Now I'm traveling a lot and got back into HAM.
    So I'm planning on putting antennas on my motorhome. One will be a 10/11 meter and the other a 2m/70cm.
    Both will be mounted at near the roof line line on each ladder rail.
    I plan on a firestick 3' on a spring and quick disconnect for the HF and a Larsen 2/440 on an NMO.
    I plan on running 213 for each. Each run will be about 50'.
    I will also have a 102" whip on spring and disconnect I can use when not traveling.
    I will also use the 102" to replace the 4' firestick on my Jeep while exploring.
    I considered lmr400 but thinking 213 is better for vibration.
    I'll be running 125w on HF and 50w on UHF/VHF. FB_IMG_1551584794431.jpg
    Any thoughts?
     
  2. KB3WFV

    KB3WFV Premium Subscriber QRZ Page

    213 will work and so will LMR 400 UF or ultra flex. It has a stranded center conductor.

    I don't think the antennas will perform well for you due to the lack of ground plan or metal directly under the antenna. Placing the antennas on the motor home ladder most-likely will be a poor ground connection. Possible causing problems with SWR. Will it work? yes but not as well as it could and probably only until you rip the mounts off while wiggling through a camp ground.

    Transmitted RF is an ac voltage that needs a return path to the transmitter (radio) much like 60 cycle ac returns to the main panel through the neutral. Traditionally, most rv's do not have a lot of metal in the roof or walls.


    If planning to only operate while stationary or set up in an RV campground, consider mounting the 2/440 antenna to an roof top a/c unit's metal chassis or use thin 22 or 24 gauge wire spread across the roof in aspider web like pattern with an antenna in the middle. Or purchase a portable vertical antenna for HF like the Steppir Crank IR.

    If wanting to operate while mobile maybe install a screwdriver antenna like a tareheel or little tareheel on the roof of the Jeep so long as it is metal. Just run coax across your tow bar to your Jeep. When your set up camping run a coax to the Jeep, just remember to un hook it before driving off in the Jeep.

    Just my .02 cents. Have fun experimenting whatever you do.

    Brian
    KB3WFV


     
  3. AI7PM

    AI7PM Ham Member QRZ Page

    On the other hand, I know a ham who did exactly this and had no issues.
     
    K6HAG likes this.
  4. K6HAG

    K6HAG Ham Member QRZ Page

    That's what I'm thinking. Of course I will provide ample grounding to the antenna bases. Mostly going to use simplex or local repeaters with an ID5100 and take advantage of its Dstar and analog databases.
    Possibly use cross band repeater functions.
    10/11 meter would be for local jeep Club talk and on the road. My Jeep has a non metallic roof and the last thing I would want to do is add a cable to my to a bar.
     
  5. K6HAG

    K6HAG Ham Member QRZ Page

    Going with LMR 240 Ultra Flex seems most practical. Also spoke wit an Elmer or two who have done nearly the exact installation on their motorhomes with more than acceptable results.
    Thanks
     
  6. K0UO

    K0UO Subscriber QRZ Page

    You don't need big coax for your RV, use LMR 240, it is easy to run. Check out the RV guys on 7155 each morning, they have all been there and can really help you.
    The best antenna is one that is up and being used!!!
     
  7. K6HAG

    K6HAG Ham Member QRZ Page

    Yep. That's what I did. Got the mounts wired up on my ladder and ran under in a conduit to the cab underneath.
    Pop it in tomorrow and mount the radios.
     

    Attached Files:

  8. W5LZ

    W5LZ Ham Member QRZ Page

    What coax do have handy? For fairly short runs almost anything will work just fine. Fractions of a dB will make no significant differences at all. One dB isn't noticeable except with very precise meters, which your ears don't qualify for.
     
  9. NK9A

    NK9A Ham Member QRZ Page

    At our Field day outings , We have been successful using RG8 X for HF , some runs are about 75 feet .
     

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