I have a 170' length of LDF5-50A (donated) to put up soon for my 2 meter
repeater. I purchased NOS Andrew LDF5-50A DIN connectors at a Hamfest for
$20 each. These will be connected at each end to Andrew NOS F4A-PNMDM
-22-NX1 22' SureFlex jumpers (DIN to N male) acquired at Dayton for another
$20 each.
Although this cable is all commercial, it still needs to be waterproofed. I
plan to use Scotch 88 and 2228 (88 sticky side out-2228-88 sticky side in)
for waterproofing. This has proven to be waterproof on my other repeater at
500 feet. The antenna there is subject to severe weather and must be
replaced every two years, so I need to open the connection without damaging
the connectors.
Keith NM5G
-----Original Message-----
From: TowerTalk [mailto:towertalk-bounces@contesting.com] On Behalf Of
john@kk9a.com
Sent: Sunday, October 15, 2017 7:49 PM
To: towertalk@contesting.com
Subject: Re: [TowerTalk] More information about my problem; . Re: Heliax
acting strangely: Help?
I am not sure what Heliax cable you have but if it is LDF5 I would toss the
homebrew connectors and use a L45U or L45P UHF connector.
John KK9A
To: <kr2q@optimum.net>,
Subject: [TowerTalk] More information about my problem; . Re: Heliax
acting strangely: Help?
From: <kr2q@optimum.net>
Date: Sun, 15 Oct 2017 22:59:38 GMT
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
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