[TowerTalk] Cautionary tale about cable waterproofing

[Pete Smith N4ZR]

Further, and hopefully final update - found the problem.  One of the 
motor leads to the rotator had a bad solder connection right at the 
connector to enter the shack.  It had previous passed visual inspection, 
but when I forcefully wiggled it, the wire popped right off the terminal 
- I presume it was adhered there only by melted flux. Resoldered and, 
for the moment at least, no new cable needed and I'm back on the air!

73, Pete N4ZR

On 7/18/2024 3:06 PM, Pete Smith N4ZR wrote:
>
> Hi Bob - At age 83, postponing the inevitable sounds like a pretty 
> viable idea.
>
> But seriously, I will be taking a hard look at the cable and probably 
> replacing it. No direct hits, but had to replace the last rotator and 
> control box after one nearby a couple of years ago.  First time I've 
> seen water inside a multi-conductor cable, but I have to admit I 
> haven't looked before.
>
> 73, Pete N4ZR
> On 7/18/2024 1:57 PM, kq2m at kq2m.com wrote:
>>
>> Pete,
>>
>> Water inside of any cable is an issue - at a minimum it means that 
>> the there exists the possibility of a hole or holes in the outer 
>> jacket of the cable.  Has your tower been hit by lightning?  A 
>> lightning strike can easily cause heating of the cable which can 
>> cause the cable itself to swell or burst the insulation on the 
>> individual wires within the cable opening it up to shorts, especially 
>> as water gets in.
>>
>> I've had lightning hits here in CT that have caused this problem, 
>> with the rotator control box indicator acting "flakier" and more 
>> erratic with time until it stopped indicating.  I eventually replaced 
>> the rotator cable, pulled the old cable off the tower, did a 
>> necropysy on it and found areas of almost microscopic holes in the 
>> outside jacket of the cable leading to water ingress which then 
>> allowed water to get into the strands of the conductors as there were 
>> tiny but visible bulges in the white insulation around the wires 
>> where there were barely visible holes.  All of this no doubt from the 
>> multiple lightning strikes.
>>
>> The rotator still worked for months afterwards until the problem grew 
>> so vexing that I swapped out my rotator and took the rotator cable 
>> down and ran a new one.  End of problem.
>>
>> I would be more concerned with any water inside the cable when it 
>> gets cold enough to freeze, because water freezing expands in size as 
>> it becomes ice - so the expansion in volume of the ice will most 
>> likely enlarge any holes/breaks in the cable that you might have.  It 
>> might also break individual strands within the wires.  Not a 
>> situation you want.
>>
>> The problem with lightning strikes is that often you can't see where 
>> the holes/breaks might be on the outside of the cable. And then you 
>> can't see any holes/breaks on the inside of the cable because of the 
>> outer jacket.  So you may or many not have a problem.  But if you do 
>> see bulges or holes/breaks in the cable, then you should replace it.  
>> Otherwise you just postpone the inevitable as the cable will 
>> eventually fail.
>>
>> 73 and GL!
>>
>> Bob, KQ2M
>>
>>
>> On 2024-07-18 08:56, Pete Smith N4ZR wrote:
>>> It's hard to say whether the water has anything to do with my 
>>> rotator's current failure to turn. Internal insulation looked fine, 
>>> but  I measured 60 ohms between the two motor leads at the bottom of 
>>> the tower - if the rotator is up against the limit stop (as I think 
>>> it is), then the limit switch should have opened and there should be 
>>> no connection at all.  From memory, I think the motor winding should 
>>> have been around 8 ohms.  Looks like the antenna needs to come down 
>>> to determine where the problem is...
>>>
>>> 73, Pete N4ZR
>>>
>>> On 7/17/2024 10:23 PM, john at kk9a.com wrote:
>>>> I use THHN for the motor wires and a multi-conductor for the 
>>>> sensor.  I try
>>>> to seal the cable ends but I do not make a big effort to seal 
>>>> them.  I have
>>>> never noticed water in any of my control cables but even if there 
>>>> was, I
>>>> don't see how water inside the PVC cable jacket would effect it 
>>>> since the
>>>> conductors are insulated.  If water got inside the connector at the 
>>>> rotator
>>>> it would likely have an effect, this is common with Yaesu rotators, 
>>>> their
>>>> boot does not make it water tight.  I have had very few actual rotator
>>>> problems but I have had several issues in the last few years with 
>>>> failed
>>>> lightning protectors.  Pulse type seem especially sensitive to 
>>>> leakage.
>>>>
>>>> GL
>>>> John KK9A
>>>>
>>>>
>>>> Pete Smith N4ZR wrote:
>>>> I've been having problems with my rotator, currently stuck due west.
>>>> Today, in order to verify connection from the controller in the 
>>>> shack, I
>>>> cut open the jacket of the good quality 6 x #18 cable at the tower 
>>>> base
>>>> - imagine my surprise when water flowed out of the cut, even though 
>>>> all
>>>> the cable above that point is vertical.
>>>>
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