[TowerTalk] Crappy LMR600

[Steve Maki]

Well I guess I'm sometimes more of a stickler for preciseness in 
language than I should be.

Hardline is available in aluminum varieties as well as copper. 
Smoothwall, corrugated, spiral. Jacketed, unjacketed.

The absolute best coax for longevity is smoothwall jacketed CATV style 
hardline (available in either 75 or 50 ohm). The center conductor is 
filled, and the dielectric is bonded to the shield (not so with Heliax). 
There is no water ingress, no way. That is why the CATV companies use it.

But my main problem was your statement that only hardline can be a long 
term solution. This is false.

It seems that lot's of folks (including you) have had semi-traumatic 
experiences with water ingress in their feedlines. Here's the thing - if 
the jacket does not leak, either from porous materials/poor manufacture, 
and your coax is not smoothwall hardline, than the issue was poor 
weatherproofing at the connectors (by far the most common cause), or 
inadvertent but usually avoidable damage to the jacket. If the jacket 
itself does not leak (and even cheap CATV RG6 fits that bill), there is 
no reason why the cable can't be used in an install designed for 20 or 
30 year life. I've said this before: it's EASY to permanently 
weatherproof connectors. And it does NOT involve wrapping tape UP like 
shingles. That's a red flag, a sign that you aren't creating a hermetic 
seal, which is begging for failure.

BTW, if a cable "slips" out of a connector, that's another red flag. 
Poor cable support, poor connector installation, or maybe a cheap connector.

-Steve K8LX




On 8/24/2017 9:25 AM, Keith Dutson wrote:

> Yes, that is what I intended to say.  Upon reading again, it is not clear.
> 
> I have used LMR-600, two pieces, on my 150 foot tower.  It worked great on
> 20 and 40 meters, for about two years.  However, over time my installation
> failed, and both cables ended up slipping out of their connectors.
> Examination of the cables showed water corrosion at least 6 feet past the
> connectors.  I line near Houston, Texas, where the tower is often subjected
> to hurricanes and tropical storms.  So, my experience if far from ordinary,
> especially compared to arid climate
> 
> I learned about the long-life capabilities of Heliax hard line from Frank
> W3LPL, at Contest University.  He posed the question something like "Who
> would like to have an antenna farm designed to last 30 years."  Of course,
> all hands went up.
> 
> Turns out that lightning is also a major factor here.  A close strike feeds
> secondary arcs to the tower and coax cables.  These arcs can penetrate the
> coax jacket, creating pin holes that allow water intrusion.  Heliax is not
> ruined by this intrusion.
> 
> 73, Keith NM5G
> 
> -----Original Message-----
> From: TowerTalk [mailto:towertalk-bounces at contesting.com] On Behalf Of Steve
> Maki
> Sent: Wednesday, August 23, 2017 8:04 PM
> To: towertalk <towertalk at contesting.com>
> Subject: Re: [TowerTalk] Crappy LMR600
> 
> I must be misunderstanding you Keith.
> 
> I thought you said that copper hardline is the ONLY cable that can survive
> outdoors for extended periods.
> 
> -Steve K8LX