LMR 600 ???

Discussion in 'Antennas, Feedlines, Towers & Rotors' started by N4MTB, Nov 20, 2018.

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  1. N4MTB

    N4MTB Premium Subscriber QRZ Page

    Is it worth using LMR 600 (or is equivalent) on HF, VHF or UHF?
    At what distance does it make a difference?
  2. KK5JY

    KK5JY Premium Subscriber QRZ Page

    For UHF, sure. For VHF, probably for a long run. For HF, probably not, unless you are doing a really, really long run of cable.

    The data sheet for LMR-600 is available online (*). The thing to do is calculate the losses you will get over the length you hope to run, then decide if the cable (and connectors, don't forget the rather $$$ connectors) is worth the lower loss you will get with 600 vs. some other type.

    (*) I find it interesting that Times didn't even bother to show the losses for HF frequencies in the graph in their data sheet. :)
    KU3X and NH7RO like this.
  3. K7TRF

    K7TRF Premium Subscriber QRZ Page

    As posted above it really depends on what frequencies, run length, how much loss you'll tolerate and of course the cost and hassle factor of working with larger diameter and heavier coax with specialty connectors.

    This online calculator let's you play with different scenarios with different types of feedline to see whether it's worth it to you: https://www.qsl.net/co8tw/Coax_Calculator.htm

    For instance with a perfect match (not likely) at 146 MHz with a 100' run of cable you'd expect roughly the following cable losses:

    - LMR-400: ~1.5dB
    - LMR-600: ~1dB

    At HF it would be hard to justify half a dB, at VHF it might start making sense but that's up to you.
    NH7RO likes this.
  4. WB2WIK

    WB2WIK Platinum Subscriber Platinum Subscriber QRZ Page

    On HF I sure wouldn't bother for a run anything shorter than 500 feet.

    On UHF, I would bother even for 75 feet. On VHF, maybe anything over 150 feet.

    But it's expensive, uses specialty connectors which are also expensive and is not flexible at all, so it's kind of like wrestling with hardline. One advantage: If you use a run straight to your wattmeter, you won't need a shelf for the meter as it can just hang in midair from the coax.:)
    NH7RO likes this.
  5. N0IOP

    N0IOP Ham Member QRZ Page

    In my planning and figuring am finding that heliax is more cost effective than LMR600 in most cases.
    KC8VWM and NH7RO like this.
  6. NH7RO

    NH7RO Ham Member QRZ Page

    And probably easier to install the humungously expensive connectors for either...

    LMR-600 is good for saving tenths of dbs and burning lots of $$$. Like a top of the line Mercedes or BMW; nice if you can afford it but not really necessary 99% of the time.
    KU3X and WD4IGX like this.
  7. WB2WIK

    WB2WIK Platinum Subscriber Platinum Subscriber QRZ Page

    "My Maserati does 185
    I lost my license, now I don't drive..."
    WA7PRC and K9ASE like this.
  8. AA7QQ

    AA7QQ Ham Member QRZ Page

    The 1/4" & 1/2" connectors are not bad to get. I use RG8X connectors on the 1/4" (Shield soldered to PL-259 adapter).
    I ran 1/4 to a Discone. I can run 1KW on UHF with it. The Discone can take it. Real nice that it conforms to the house & CATV clips work fine.

  9. WB2WIK

    WB2WIK Platinum Subscriber Platinum Subscriber QRZ Page

    LMR600 uses .600" connectors and they are pretty special.

    I'd invest in this for UHF-SHF work, but for HF seems silly.

    Most SHF work is done using the TX/RX equipment right at the antenna, so the "downfeed" is at a baseband frequency like 28 MHz. Then, RG-58/U works fine for that.:p
    NH7RO likes this.
  10. KM1H

    KM1H Ham Member QRZ Page

    At those prices used Andrew 1/2" and 7/8" Heliax (or comparable competition) is a fraction of the cost and often with connectors. Plus it is direct burial capable and also makes for efficient hanging verticals.

    NL7W and NH7RO like this.

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