Topband: Why do rodents eat coax?

[Dave Olean]

You are right, Guy, but I have plenty of test gear to check coax. I can sweep it for return loss, check insertion loss and all that stuff. I use several HP scalar analyzers as well as an 8753D vector network analyzer good to six GHz. I have an Anritsu Sitemaster that has a great TDR function as well. I even have a 500 MHz 50 : 75 ohm transformer.  Being a VHF and microwave addict, I am constantly testing cables on the higher bands looking for humidity getting into otherwise new good looking cable and making things NG. Checking cables for 160 is a piece of cake by comparison. I am running the new 1000 ft run of flooded cable in conduit to my EU beverage , but I have also rejuvenated the chewed up cable and its' insertion loss and VSWR are back to normal. TDR wise, I saw the biggest bump at the BNC connector I put on one end. All the splices look pretty good.  I replaced about 15 ft of bad cable with F splices, dielectric grease, and adhesive backed heat shrink tubing over each splice. The coax was Belden flooded direct burial RG-6, and it appears that water did not move very far in the cable. I'll use the repaired cable for another beverage. There is room in the conduit for a second run of cable.

73

Dave K1WHS 
  ----- Original Message ----- 
  From: Guy Olinger K2AV 
  To: Dave Olean ; TopBand List 
  Sent: Wednesday, November 11, 2015 5:49 PM
  Subject: Re: Topband: Why do rodents eat coax?


  Gotta vote loudly with Frank on this one. 


  I had to throw away 480 feet of balanced "window" line (Wireman 554) that ran elevated from my tractor shed to the base of my 3/8 wl 160 inverted L over FCP.  The spans were supported from trees a few inches away from the trunks. Very easy access to squirrels as it turned out. They knawed the PE insulation off the wires enough that water seeped the entire length of the seven copperweld strand conductors on both sides. Forever ruined for transmission purposes. Junk. 


  It slowly robbed me increasing ultimately to 3.8 dB extra loss. No sudden change in performance to sound the critter alarm.  



  Dim view from here of reusing that knawed RG6. To put it bluntly if you can't scan it for loss and impedance anomalies, chuck it and save yourself a lot of trouble. 


  73, Guy K2AV 


  On Wednesday, November 11, 2015, Dave Olean <k1whs at metrocast.net> wrote:

    Thanks to all who responded with all sorts of great hints and ideas for combating the rodent problem with beverage feedlines. I ended up going with buying 1000 ft of 1/2" PVC conduit and will lay that on the ground through the woods. I ordered a new 1000 ft roll of RG-6 flooded cable to use inside the PVC.  I also removed my existing 1000 ft run of coax and gave it a good inspection looking for chew marks. After laying the coax out in my open field, I identified five areas where the critters had chewed it. At least three of the spots were severe with chewing marks that went deep down to expose the center conductor. I can cut the bad parts out and will only lose about 10-12 ft of overall length. I'll put F fittings and splices there and will try to reuse the old cable as well. It won't fit inside the PVC along with the new cable, but hopefully, I can bury it enough so that it lasts a few years. I was hoping to add another beverage at the same spot with a second feedline. I can
      lay out an 800-900 ft wire aimed at Africa and the middle East. That is an area that I have had nothing in the past, so maybe I can improve things while I repair the rodent damage.  Those darn critters sure caused a lot of damage and expense!
        Anyway, thanks to all who responded. I appreciate all the great comments and ideas.
    73
    Dave K1WHS
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