Looking for Coax Recommendations

Discussion in 'Satellite and Space Communications' started by KF0FQL, Sep 16, 2021.

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  1. KF0FQL

    KF0FQL Ham Member QRZ Page

    Currently i'm working the FM birds with an Arrow antenna (with duplexer), Icom IC2720 and a 10 foot section of RG8x.

    I am considering taking my Icom 821h and making it portable so I can work linear birds. So i'll need two coax one for the uhf and one for the vhf to run to the Arrow bnc connectors.

    I would be doing this from the trunk of my car so i'm thinking 10' max length needed on each piece. What would be the recommended coax for this WITHOUT breaking the bank?

    Thank you in advance!
    Jessica
     
    KA0USE likes this.
  2. KA0HCP

    KA0HCP XML Subscriber QRZ Page

    RG-8X (Mini-8) is an inexpensive and satisfactory feedline.

    Running a loss calculation show 0.82 dB loss in 10ft of Belden RG-8x with 1.1 SWR antenna load. Loss would be less on 2m. This low level of loss would hardly be detectable by ear, especially inside a running car with traffic noise nearby.

    You can run your own calculation estimates here:
    https://www.qsl.net/co8tw/Coax_Calculator.htm
     
    KA0USE likes this.
  3. KC3RN

    KC3RN Ham Member QRZ Page

    Hi Jessica. For such a short run you don't need great coax, even on 70cm. Even RG-58 will have relatively low loss.

    These are really inexpensive, and decent quality. I use the 6' version with my Arrow.
    https://www.allelectronics.com/item/cbl-29/15-bnc-bnc-cable-rg-58/1.html

    RG-8X will have better loss numbers on paper, but again, with only a 10' run you won't notice much difference.
     
    KA0USE likes this.
  4. K8HIT

    K8HIT Premium Subscriber QRZ Page

  5. K3RLD

    K3RLD Ham Member QRZ Page

    I tend to agree with all of the above. If you want to splurge, go with LMR240UF. Be sure to get the UF (ultraflex), as I made the mistake of ordering the regular stuff once and it is stiff as a board. Even the UF is "stiff" compared to RG-8X.
     
    VE3TSV and KF0FQL like this.
  6. KF0FQL

    KF0FQL Ham Member QRZ Page

    I was thinking about that as I heard the LMR400 was stiff and I don't want to fight coax especially working out of my trunk if it's a winter day. I will look at these calculators people are linking me to, even though I don't really understand them all that much. But I do have a question.. someone mentioned to me that LMR400 is great for UHF not so much for VHF... should I be getting two different coaxs?
     
  7. KB1PVH

    KB1PVH Ham Member QRZ Page

    I don't use anything less than LMR240UF for portable. It's honestly not much more as far as price goes. Dave KG5CCI makes cables up for satellite people if you're looking to get good LMR240UF cable assemblies. I know the loss calculations aren't much for a 10' length, but I vehemently disagree with RG58 for UHF/VHF. There's been a few instances where people weren't doing well with their Arrow and switched to LMR240UF and suddenly they were able to hear SO-50, YMMV.
     
    KO4MA and K4BAD like this.
  8. AI5DH

    AI5DH Ham Member QRZ Page

    Your goal is 2 dB or less loss. At 10-feet just about anything will be less than 1 dB
     
    KC3RN likes this.
  9. KS1G

    KS1G Ham Member QRZ Page

    LMR240-UF and GOOD connectors (KG5CCI, I've had good results with MPD Digital/USACoax, RF Connection (theRFC.com)). RG8X if that's what you have/can afford. Consider having a 3rd cable (saved a trip when my primary one had a failure) as a spare. For my Arrow, I have BNC-N on both and use a N-PL259 adaptor for the VHF side; or get a BNC-N and BNC-PL259. I also use color tape to color code my cables to make quick setup a little less error-prone.
     
    K7WDO and KF0FQL like this.
  10. N4UFO

    N4UFO Ham Member QRZ Page

    To me, LMR400 would be overkill. Too big and heavy for portable satellite purposes. You will wear your arm out waving the antenna around.

    I completely agree with Dave KB1PVH... by swapping RG-58 for low loss RG-8x (not just any RG-8x though) many have seen improvement.

    Only RG-8x size coax I know of that has better loss figures than LMR-240UF is Wireman's CQ-118 coax. (Only slightly better, between the two go for the best price and desired connectors.) Wireman sells CQ118 with PL-259's in premade lengths of 6, 9 and 12 feet: https://thewireman.com/?s=Cq118&post_type=product
    LMR-240UF can be found in all manner of configurations and lengths on eBay as well, but can be a bit more pricey.
     
    Last edited: Sep 17, 2021

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