David
A few observations from Hot, Humid Central Florida.
9913 can work if properly installed and
WATERPROOFED. I have used a few runs here in
the humidity of central Florida for over 15 years with no water intrusion.
The outside connection must be sealed with a good
grade of Coax seal or Butyl Rubber tape and I use
at least 2 layers of 2" plastic tape followed by
3 layers of 3/4" of good electrical tape (like
Scotch 33, 88 or 700). I apply the coax seal
directly to the connector and the coax then three
layers of tape extending at least 1" past the
Coax seal. I leave the inside end unsealed in
Air conditioned space so any air entering the
cable (and it will due to expansion during the
heat of the day and contraction during the cooler
night) will be dry air. If both ends are exposed
to the weather it will draw in humidity at night
or during rainstorms. Store the cable in "Air
Conditioned" space prior to installation to
minimize the humidity within the cable.
For runs of 100feet or less use 9913F7 or LMR400
flex. and forget about the jumper around the
rotor. If you want to run 9913 or LMR400 and
have a mast mounted preamp - mount the preamp
under the rotor and run the flex jumper from the
preamp to the antenna . Connectors sized for the
9913 inner connector work fine with LMR 400.
Another great alternative is 1/2" Andrews
superflex ( I have used this stuff on 2304 for a 70' run)
For runs over 100 feet look for either LDF 4-50
or LDF 5-50 at area swap meets and
hamfests. You usually can find the connectors
at the same place or watch e-bay for connector
bargins. Another alternative is 75 ohm CATV
hardline (only 1.5:1 SWR) Connectors are easy to fabricate.
Again on waterproofing, even "N" connectors will
draw water into the connector over time when not
sealed with coax seal - the center chamber in the
connector has some air space that expands and
contracts with temperature changes. I follow the
Andrews guidelines packed with their waterproofing kits:
Installers should become thoroughly familiar with and use the installation
tips given here.
Installation Tips
? When applied, the tape must be above 32°F (0°C) to ensure
adhesion. Keep tape warm by carrying in coat pockets.
? Do not stretch the tape. Apply only enough tension to provide
a smooth wrap.
? Smooth each wrapped layer with your hands to ensure
full adhesion.
? Do not pull the tape to tear tape ? always cut it.
(Pulled tape eventually unravels, decreasing protection.)
? Add extra final layers of tape in warmer climates where there
will be long exposure to damaging ultra violet (UV) rays. Two
or three extra layers of tape will provide additional UV protection.
? When wrapping tape, overlap the tape to half-width.
? Ensure vent or drain holes at the bottom of the antenna
or device are not covered with weatherproofing tape.
If you can find them at a hamfest the Andrews
water proofing kits are a great value - Andrew
221213 Weatherproofing Kit contains:
2 rolls of 3/4" x 66' black plastic tape
1 roll of 2" x 20' black plastic tape
6 rolls of 2-1/2" x 24" butyl rubber tape (coax seal)
Vry 73
Bob Cumming
W2BZY
QRV 160M-9 CM +3CM
from EL98hr
At 01:35 AM 7/9/2006, David Ashworth wrote:
> Hi to all, thank you for the answers to my previous questions about
>stacking and rotors. I learned a lot. Now, a couple of questions and
>wonder what you are using that works. Here is the statement and the
>questions: Have some 9913 that feeds a multi-band vertical for 5 years or
>more. Heard that it may suck up water, no troubles yet. Now, we write a
>clean slate. Say I would like to put up beams on a new mast for 50 and 144.
>What coax would the group recommend? I am curious, I have heard about this
>LMR-400, etc, but have not seen any of it. If it is like 9913, it would
>not like to turn around and around. What connector from the high dollar
>run (LMR) to the pigtail coax that likes motion would you advise? What type
>of coax would you use for the pig tail? Just full of questions. The run
>would be 100'. Thank you much for your assistance, Dave, NC6P.
>
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