Hi Jim,
There's no limit switch or other form of protection. There's a break in one
or more wires.
It's not likely that there's a break inside the main control cable unless it
somehow got really abused during installation or has gotten pinched
somewhere. It's more likely that one of the wires isn't making contact at
the terminal block (if you used the standard connection method.) It's pretty
easy for the stripped portion of the wire to break if it's bent or stressed
after you tighten the terminal block screw. This can happen when you stuff
the terminal block into the PVC tube. That's one of the reasons I stopped
using the terminal block and now use weatherproof telco connectors.
If you're measuring an open circuit from the base of the tower to the
antenna, you or your installer will have to climb back up there. I would do
the following:
1. Look for obvious damage to the cable on the way up.
2. Pull the terminal block out of the PVC tube and inspect the driven
element connection (inspect all of them while you're at it.)
3. If one or both wires are broken, fix them.
4. If the connection looks good, disconnected the pair coming from the main
cable.
5. Measure resistance of the pair going from the terminal block to the
motor.
6. If you still get an open circuit, the cable to the motor is damaged.
It's fairly easy to damage the EHU cables. They're relatively thin and very
exposed during installation. If you taped them to the underside of the boom,
the cable to the driven element EHU could have been damaged if the boom hit
the tower on the way up. On one of my 4-el SteppIRs, I stupidly mounted the
u-bolt for one of the 6m passive elements *over* the EHU cable instead of
under it. That compressed the cable, broke through the sheath and snapped a
couple of wires. I was lucky the wires didn't short to the boom -- that
would have burned out the driver chip, which is SMD and hard to replace. I
was also lucky that I could reach and fix the element mount and wire from
the tower (it took quite a stretch!)
If you have any more questions, just ask.
73, Dick WC1M
> -----Original Message-----
> From: Jim Brown [mailto:jim@audiosystemsgroup.com]
> Sent: Monday, July 20, 2009 11:39 PM
> To: Tower Talk List
> Subject: [TowerTalk] SteppIR Wiring Problem
>
> Crew,
>
> I just got my SteppIR up to 120 ft and it's giving my awful SWR
> readings. In troubleshooting, Using an ohmeter with the control cable
> disconnected from the controller, I'm reading open circuit on one of
> motors for the driven element. All other motors read normal (28 ohms
> from my controller), and they worked fine with that controller and
> that exact piece of cable at 20 ft. For further troubleshooting, I've
> broken the control line at the base of the tower, and the open is
> above that point. I suspect a broken wire or bad splice at the boom,
> but am wondering if there is a limit switch or any other form of
> protection that might have kicked in?
>
> 73,
>
> Jim K9YC
>
>
>
>
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