[TowerTalk] More information about my problem; . Re: Heliax acting strangely: Help?

[Steve Maki]

Doug,

Heliax uses closed cell foam so the dielectric itself doesn't wick 
moisture, but there are voids between the dielectric and shield that can 
wick water. You must ensure a seal at the ends of corrugated hardline if 
you want a long life feedline.

Did you place the dummy load right at the end of the Heliax, or at the 
end of the top jumper?

-Steve K8LX

On 10/15/2017 18:59 PM, kr2q at optimum.net wrote:

> I was wondering why I did not get any follow up emails to my original.  I had made an additional post,
> but in error, I only hit reply and it never went back to the group.  So trying again.
> 
> As a reminder, I have 160' run of 7 eights Heliax what worked fine all last summer, fall, and winter.  Last time it
> saw power was  at the end of January.
> 
> About 6 weeks ago, I turned on radio and shot out 100 watts and found an SWR of 3:1.  I did all the normal checks and the
> problem is actually the coax.  Putting a dummy load at the far end still showed 3:1 and when I put the dummy at the jumper
> feeding the near end (in other words, bypassing the coax), the SWR was 1:1.  I opened up both ends and found no water and
> no moisture.  Sorta like the X-files.  It's not the antenna, so you don't need to know what it is.
> 
> Here is my additional post from a month ago.
> de Doug KR2Q
> 
> I have multiple responses already.  Here is some more information.
> 
> I do not have real connectors for 7/8 Heliax.  I took a chassis mount SO239 and soldered it to the cut end
> (each end) of the heliax.  I used copper wire to make the connections.
> 
> Therefore, there is no water in the connector because there isn't a "connector." I did have them taped up with Scotch 88.
> 
> When I opened them up, there was no moisture inside and certainly no liquid water.
> 
> Both ends were, and are, well above ground (measured in feet), so no, they were never sitting in water.
> Each end has a "loop" of RG8 connected to it, so there even if rain were to "run down the coax," it would
> or should just drip off the bottom of the RG8 loop...no way to travel up hill back to the "connector" with the Heliax.
> 
> The connections (wire soldered to the outer conductor and to the center conductor) are no longer "shiny" but are electrically sound (DC).
> 
> As I said, this has been in use since last Summer, through the fall and winter (through Jan 21,  2017) without issue.
> 
> As for water ingress, where would that occur?  Would the dielectric "suck up water?"
> 
> I really can't see where the water would come from and if any, "not enough" to make that
> much of a difference in the course of ~6 months?
> 
> I don't have a TDR and locals who have responded have various MFJ analyzers, but not one
> that has TDR capability.  But seems that is a good route to follow.  Would be great to identify
> an impedance bump somewhere.
> 
> Yes, at some point, I can cut off the ends and see what happens, but how much should I hack off?
> 
> Any other thoughts?
> 
> Thanks
> de Doug KR2Q