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"Buried" Coax

Discussion in 'Antennas, Feedlines, Towers & Rotors' started by W4MUF, Jun 14, 2018.

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  1. W4MUF

    W4MUF XML Subscriber QRZ Page

    I'll be installing a Hygain AV-640 in the next 2 days and it will be in the backyard about 50 ft behind the
    house. I was just going to dig a shallow trench and put it in there. However, I was wondering if it is OK to bury coax underground. Will I be replacing it in a year or two? Did not want to just lay it on the ground, afraid it might get caught up in the mower blade.

  2. WD3N

    WD3N Premium Subscriber QRZ Page

    1 1/2" PVC conduit costs $7 per 10 ' section.
    Protect the coax from digging damage , and can be replaced without digging..
    A pull string can be put in as you install the conduit , or be pulled through with a vacuum cleaner.

    There would be room to add other cables.
    N0TZU likes this.
  3. K7GQ

    K7GQ Subscriber QRZ Page

    I use Bury-Flex (RG-213) from Davis RF which is suitable for direct burial. One of the problems with buried conduit is the accumulation of water meaning that you'll need to add drain holes. Otherwise, the suggestions just above are good.
    W4IOA likes this.
  4. NN4RH

    NN4RH Premium Subscriber QRZ Page

    If the coax is rated for "direct bury" it will be fine buried directly.

    The antenna connection end should be sealed well, and not lying on the ground, or water could infiltrate into the shield from the end over time.

    I've used Bury-Flex RG-213, too, for about the past 17 years. The only time I've had a problem is my first installation where the "pigtail" at the antenna end was not sealed and was lying on the ground. Water had infiltrated and corroded the shield for several feet, and increased cable losses about 0.2 dB.
    N0TZU likes this.
  5. N8AFT

    N8AFT Ham Member QRZ Page

    Big Box home stores carry lawn staples, like what you will use when you tie down the radial wires for this vert.
    I staple my coax to the sod and let the grass grow and the thatch will cover it well.
    No need to worry about the mower, set the deck height up a notch is all.
    If you must bury, what I did was use a power lawn edger to make a simple shallow trench and laid the cable on sand in trench.
    Covered with sod, tamp with feet. I used direct burial RG-213.

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  6. AI3V

    AI3V Ham Member QRZ Page

    I'd worry a whole lot more about waterproofing connectors than burying coax.

    W7UUU, N0TZU and AK5B like this.
  7. KA9JLM

    KA9JLM Ham Member QRZ Page

    For the best protection You can run it in 1/2 or 3/4 inch PVC pipe and use a sharp shooter to put it just below the surface.

    No reason to dig a trench. Just open a slot in the ground.

    W4IOA, N0TZU and AK5B like this.
  8. N0TZU

    N0TZU Platinum Subscriber Platinum Subscriber QRZ Page

    Yes, it will be fine with direct bury type coax.

    BTW it would also be fine in conduit. I have had mine in 100 feet of conduit for years, along with control cables. Some water will accumulate in buried conduit, more or less depending on climate and weather conditions. But it won't affect the cable - consider that there's lots of water in soil too, especially in some regions or locations.
    AK5B likes this.
  9. WT4W

    WT4W Ham Member QRZ Page

    This is what I've done, it's the easiest option and it works just fine. After a few months you won't even be able to see the coax.
  10. AK5B

    AK5B Ham Member QRZ Page

    No one has yet mentioned that direct bury coax is gel flooded in case of jacket damage; while DB is ideal in most every situation you can still get by fine with regular coax (assuming it will be out of harm's way from rodents, rototillers, heavy equipment rolling over it, etc).

    I have 6 or 7 runs of shallow buried coax across my back yard and so far, so good.

    I used one of these to cut a slit which is pushed back together after coax is inserted:

    $25 at Lowe's

    Aerial view taken at dusk for a record of where i buried this run (it disappears once the lawn is back together).

    Hope this helps and be prepared for gophers in any case. We have them here but no problems yet; if I notice anything odd with my SWR I'll simply replace the coax.

    If you want something good and durable (and is rated for DB get the orange RG-6 from Amphenol) . It's 75 ohms so you'll need to take that into account (I use mine on a monoband antenna and cut the length at a half-wave multiple and factored in the .85 velocity factor)---works perfectly.



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