[TowerTalk] Heliax acting strangely: Help?

[John Lemay]

Yes, water ingress.

If you are lucky, it is at one end or other.

Remove both connectors, examine for dampness / corrosion. If necessary allow to air dry or use gentle heat. Re-check for infinite resistance between inner and outer.

John G4ZTR

-----Original Message-----
From: TowerTalk [mailto:towertalk-bounces at contesting.com] On Behalf Of chuck.gooden
Sent: Sunday, August 27, 2017 12:53
To: kr2q at optimum.net; towertalk at contesting.com
Subject: Re: [TowerTalk] Heliax acting strangely: Help?


    
Improperly installed connetor that allowed water to ingree the cable?

Chuck Gooden - K9LC

-------- Original message --------
From: kr2q at optimum.net
Date: 08/27/2017  6:25 AM  (GMT-06:00)
To: towertalk at contesting.com
Subject: [TowerTalk] Heliax acting strangely: Help? 

I put out a 160 foot run of 7 eights heliax last year.  Worked great.  Last time I was QRV was end of January, 2017.

I recently put some RF out (100 watts...HP for me) and was surprised to see an SWR in the shack of about 3:1.

Setup:
Outdoor antenna switch box just outside the shack. From there, very short run of RG8 (under 4 feet) to "start" of Heliax.
160 foot run of Heliax to "back" tower.
Then another "short run" of RG8 to about 80 feet of RG217, which goes "up" my crankup tower.

What I have done:
Put a dummy load at the rig: shows 1:1 SWR.

Put the dummy load at the "far end" of the heliax by "breaking" the connection from the Heliax to the short run of RG8.  SWR in the shack still 3:1 (all HF bands).

Put the dummy load at the end of the short run of RG8 coming from the antenna switch box.
SWR in the shack shows 1:1 (dummy working, coax to that point working).

OK, so seems like something is wrong with the Heliax.

I disconnected the Heliax at both ends.  If I short inner to outer, it shows dead short at the "other" end.  I know, DC is not RF.

I measure the resistance between center conductor and outer shield of the Heliax.  I expected "infinite," but using my crappy RS ohmeter, it shows about 500k ohms.  I measured other runs I have RG217 (nothing connected at either end, about same length), and the crappy RS meter shows infinite, as expected.

So what could go "wrong" with my 7 eights inch Heliax?  It is above (on) ground for the entire length.

I walked it yesterday, picking it up about every 10 feet.  Looked "normal" to me.

Any help/suggestions?

Thanks,
de Doug KR2Q


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