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  1. #31
    Bald Tire
    Join Date
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    Laguna, great explanation. I didn't realize the GMRS could use repeaters. I am just using the lower power hand held Midlands. Thanks.

  2. #32
    El Diablo
    Join Date
    Sep 2011
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    Scottsdale
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    Got the antenna installed and tested it with a new UHF SWR meter, since the CB meters won't work on this. I had a different antenna yesterday but it was defective - it appeared to be a customer return and that person got the set screw stuck inside the coupler, not allowing the stainless rod to seat properly. It's a long, 38" whip antenna but it folds over for low parking spots. Amazon is sending a replacement that will arrive tomorrow

    With this stubby antenna, I tested 1.3-1.4 on most channels, with about 1.1 on a few channels. https://www.arcantenna.com/products/...e-omni-antenna. I wasn't sure if it would work well with the expanded metal of the roof rack as the ground plane, but it did well. It's not tuneable, so I'm glad it did well. I was also stoked as it shipped from Tempe, AZ - about 10 miles away.

    The mag mount is this one: https://smile.amazon.com/gp/product/...?ie=UTF8&psc=1. It's holding pretty well against the roof rack, but I may add a couple of zip ties to fully secure it. The magnet holds better than the Lil' Wil CB antenna did on the same part of the rack.

    The whip antenna I'll be testing, and perhaps using for longer range situations, is this one: https://smile.amazon.com/gp/product/...?ie=UTF8&psc=1. While it says it's "pre-tuned" there are provisions for tuning it as there are set screws to make it longer or shorter. However, unlike CBs where you test channels 1 then 40 to determine if the antenna is too long or too short, I think I have to test differently. I plan to assemble it, test it with SWR. If it's not perfect, I may lengthen it a bit to see if the SWR goes up or down. If it goes up, I may shorten then antenna a bit (like 2mm) to get it lower. But if it's settled in about 1.3 or less I'll be happy.

    UHF SWR meter and adapter cable: https://smile.amazon.com/gp/product/...?ie=UTF8&psc=1, https://smile.amazon.com/gp/product/...?ie=UTF8&psc=1. The cable is a 2 pack so I have an extra one if anyone locally needs it.

    The 90 degree plate you see in the background is the old mount for the CB, allowing me to move the antenna to horizontal when not in use. Borrowed the idea from PreferredChassisFab.

  3. The Following 2 Users Say Thank You to alrock For This Useful Post:

    LagunaH1 (04-22-2021), rascole (04-22-2021)

  4. #33
    Super Swamper
    Join Date
    Jun 2015
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    Way up north, UT
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    Had to go dig mine out of the FCC's website:

    WRCX566

    Need to update my contact info for that one, it's still listed as my old address.
    2008 H3 Alpha

    "Live free or die: Death is not the worst of evils." - General John Stark

    N1JPA

  5. #34
    Super Swamper
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    Little changes to the antenna tuning can make a big difference since the wavelength is so short. That's why most of those antennas aren't tune-able really, they don't really need to be. As you go down in frequency (longer wavelengths) it becomes more challenging to tune the antenna on mobile since your ground plane (car) is correspondingly smaller. Once you get into the HF bands it becomes all kinds of fun trying to keep your SWR low. Part of the reason the screwdriver antennas are popular since they are multiband and act like an antenna tuner to help keep SWR under control.

    The wavelength for GMRS is roughly 65cm (25 inches). That's a full wavelength. Most of the antennas are probably 1/4 wavelength which is only a bit over 6 inches. You can go to 1/2 or 5/8ths wavelength and get a bit better performance depending on the setup, but then that's only 12-16 inches or so for GMRS. Looks like that dual band whip Alex linked is treated as 2x 5/8 wavelength antennas on 460MHz (GMRS).
    2008 H3 Alpha

    "Live free or die: Death is not the worst of evils." - General John Stark

    N1JPA

  6. #35
    El Diablo
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    Did a short tuning session with the 38" whip. Out of the box I was getting 1.2-1.3 on some channels, and 1.6 on others. I tried lengthening a bit, and it got worse. So I shorted it a bit, and it got worse. Ugh. Didn't feel like playing with it anymore so I put the stubby back on.

    Driving the H3 last night I scanned some channels and found a conversation between two dudes talking about having a barbecue. I drove about 5 miles and they stayed clear as could be the whole time. I think they were both stationary based on their conversation. That performance made me very happy with the stubby antenna, though admittedly I was in a pretty flat part of the city.

  7. #36
    Super Swamper
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    Quote Originally Posted by alrock View Post
    Out of the box I was getting 1.2-1.3 on some channels, and 1.6 on others.
    Those are good numbers.
    2016 RAM 2500 Power Wagon
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    NR6E

  8. #37
    El Diablo
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    It's the 1.6 that I didn't like, from channels 15-20 if I recall correctly. It was great on 1-7 and 21-22

  9. The Following User Says Thank You to alrock For This Useful Post:

    LagunaH1 (04-26-2021)


 

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