Wise to Bundle Mobile Cables?

Discussion in 'Mobile Radio Systems' started by NO6O, Jan 6, 2011.

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  1. NO6O

    NO6O Moderator Volunteer Moderator Platinum Subscriber QRZ Page

    I usually get on the air via mobile. However, I use the same radio for mobile and portable use. As my QRZ page shows, my radio equipment is contained in a computer carrying case. After connecting my cables and antenna, I'm on the air within a few minutes.

    However, my cables are too disorganized when the radio is not set up. One thing I did to clean things up was to bundle the HF, VHF/UHF, and screwdriver contol cables together. I figure there would not be any interference, or other trouble, because only one cable is really in use at a time.

    Then, I wondered about adding the power cable to the bundle, and then thought it could possibly cause various issues. Up to now, I've been having great performance, however I want to avoid jeopardizing anything.

    Therefore, my question is, what problem(s) could occur, if any, by having these cables bundled?
  2. KA0HCP

    KA0HCP XML Subscriber QRZ Page

    The only problems I can think of are: RFI; Overheating due to lack of airflow.

    If you don't have a problem, there's no problem. :)
  3. NO6O

    NO6O Moderator Volunteer Moderator Platinum Subscriber QRZ Page

    Well, I'm not having a problem with airflow. I'm just wondering whether coax cables get along well with a 12v power line carrying around 20 amps.
  4. AG3Y

    AG3Y Guest

    In Broadcasting, we always kept the RF, Video and Power lines separate!

    At least that is the way I was taught that it should be.
  5. NO6O

    NO6O Moderator Volunteer Moderator Platinum Subscriber QRZ Page

    Yes. That's what I was wondering. I think the separation of power and signal rules over neatness. Thank you.
  6. WB2WIK

    WB2WIK Platinum Subscriber Platinum Subscriber QRZ Page

    I have a different take on this.

    Broadcasting usually involves more power than "we" run, and they can't tolerate any noise anywhere. Plus, "power" in broadcasting is usually AC at 60 Hz, and not DC. Hams don't need to be quite so perfect.

    I have everything "bundled" in my mobile installation. DC power (14V at as much as 40A), coax, rotator cable, DC bias for topside regulators and transverters, I.F. lines to the transverters, 10 MHz Rubidium standard frequency control lines -- just everything -- into a neat bundle that is tie-wrapped together and have no issues of any kind. Now, there aren't any audio or modulation lines in that bundle, just DC and RF.

    No issues at all.

    I like to make things very neat, with a single "harness" that does everything, and it's always worked for me. I like that "spiral wrap" stuff that allows you to make a flexible conduit for all cabling (they sell this at all the computer stores), it's pretty neat.

    I don't think I'd want AC power at 60 Hz bundled in with everything else, but if you're talking only DC, RF and control lines I can't see why it would be a problem.
  7. NO6O

    NO6O Moderator Volunteer Moderator Platinum Subscriber QRZ Page

    That *IS* a different take on it. Thank you. That makes a lot of sense, too, regarding DC vs. AC. I might get some flexible plastic conduit to route the wires. Tie-wraps are good, however after putting them on, I will probably soon have a need to add another cable or wire.
  8. AG3Y

    AG3Y Guest

    Steve's "spiral wrap stuff" is pretty good, as long as you do not get beyond an inch or two bundle to wrap together. If you go too big, you will end up with a frustrating job of trying to get the spiral to be wrapped neatly around the big bundle.

    Yes, it is true that mobile power is DC, and not 60 Hz, so you might be able to get away with it. Be sure you use 1st class coax, though. You do not want RF getting into the lines that are feeding DC power to the rigs. The best way to keep that from happening is either separate the lines, or use good coax with really tight shielding. None of this Radio Shack stuff where you can see the plastic center insulation between the weaving of the shield !

    Actually, Steve, there is a waveform riding on top of that DC level though. It comes from the alternator, and produces a "whine" that can get into a poorly filtered radio via the power lines. That is where the old idea of tapping the power as close to the battery came from . The closer you get to the battery, the less of that whine you will probably hear!
  9. KA0HCP

    KA0HCP XML Subscriber QRZ Page

    That is a question only you can answer! After bundling do your power cables get too hot? If there is any question about the coax, you can look up the manufacturers temperature spec if it isn't labeled on the covering.

    I did have a friend once complain to me that the radar transponder in his airplane was reported as intermittent. Come to find that he had routed the coax beside the foot warmer duct, just as the coax made a bend. The dielectric has softened from the heat and allowed the center conductor to migrate close to the shield. On warm days it worked fine because the dielectric was cool and solid providing insulation. On cold days the duct would be hot, the dielectric flowed and the wires shorted. :) We replaced the coax, rerouted it and put some insulation and aluminum tape over the air duct.
  10. K8JD

    K8JD Ham Member QRZ Page

    I would run the coax well away from control and DC wiring
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