[TowerTalk] NEMA Box for poly phaser and Coax connections
grants2 at pacbell.net
Sun Dec 31 17:47:22 EST 2017
With an 800' run to the tower, you want the largest coax you can afford
on those runs to the "tribanders"
The way I analyzed my situation is in the spread sheet sent direct. My
target was < 1 db loss in the coax 80m thru 10m, amp output to yagi
feedpoint. Achieved that but my runs are much shorter than yours.
142' Rohn 65, 2L 80m @157' (prop pitch) , 3L 40m @ 140', 5 over 5
monobanders on 20, 15 & 10 (7x KX0G rings). see qrz.com KZ1W
I ran 7/8 coax LDF5 inside my tower for 20 > 10. LDF4 for 40 & 80. The
7 ring rotators and the prop pitch use Buryflex jumpers. All outside
connectors are 7/16 DINs except for the rotator pigtails are N with N to
DIN adapter. Inside PL259s and more Buryflex. Every inch of coax is in
the spreadsheet. Chokes I made at each feedpoint are in outdoor PVC
J-box with watertight glands - no connectors out on the booms.
All of the tower coax is held with commercial leg clips and bushings the
correct size for the hardline (from Tessco). LDF4 one leg, LDF5 on the
second, and all control lines on the third. I highly recommend doing
that as loose hardline in the wind doesn't last long and you have the
tower motion as well.
A large bonding plate about 4' from the tower base is on the side of a
4' x 6' by 8' tall "dog house". Andrew bonding kits on the hardline
shields. All the stackmatches and rotator amplifiers are inside. I
made the ceiling removable 2x4's so I could lay all of the phasing LDF5
coiled inside. No phasing lines on the tower. Wish I'd made the dog
house a bit bigger, say 5 x 8' and another foot taller.
The coax shack to doghouse is underground 3x 3" sch40 PVC conduits, LDF5
for 20 > 10, LDF4 for 80 & 40.. 2x 7/8 + 1x 1/2" is about the limit in
3". I used the biggest sweeps, 36" radius.
At the shack end I used a 48"T x 36"w by 24" deep 2 door office cabinet
set over the conduit ends, DIN to PL adapters and Buryflex jumpers
inside via 3" conduit stubs to 2x 8x2 switches for the R65 and other
towers and antennas. Painted the cabinet for WX protection. A Hammond
fiberglass that size is ~2 kilobucks and my dog house cost a lot less
4 year reliability has been excellent except for two N connectors I
didn't crimp properly. Having the tower guy back for a 125' climb makes
that a very expensive N!. The other I got with a rental boom lift as I
don't climb any more.
Take pictures of everything up the tower from about 5 perspectives.
On 12/31/2017 11:40 AM, CEPitts wrote:
> First time poster so please excuse if I do not do this correctly:
> Rotating Tower
> I know bigger is always bigger than smaller due to possibly having to
> add items *(Box size)*
> I will have 7/8 " cell flex hard line entering box to feed a WX0B six
> way switch as well as a WX0B stackmatch to three antennas (2
> tribanders 40-10M and one 6m beam ) on tower as well as wire dipoles
> for 80M and 160M. The wire antennas hung from 60-80 foot pines as well
> as the 160M Inv L.
> Also one rotor control cable and two control lines for the six way
> switch & stack match.
> As far as lightning protection looking at installing some polyphaser
> components to protect everything
> Questions are is it wise and cost effective to place all in one box?
> if so what size?
> If not should I place all coax feeds both the incoming 7/8" cell flex
> hard line and feeds to all of the antennas on the tower & to the
> dipoles/Inv L in one box with all of the switching components (WX0B)?
> And all of the polyphaser in another box?
> I'm all about eliminating loss so what is a good flexible jumper to
> use from the 7/8" hardline going to the box to transition to the three
> antennas on the rotating tower? In other words jumpers from the six
> way switch/stackmatch and eventually out to the rotating tower
> Frank W3LPL says the Davis Is some of the best and I have 1000 feet of
> it, ie regular coax the size that is 213, will that be good enough
> going up the tower to the three antennas I plan on putting there or
> there is a alternative great flexible feed to feed those antennas to
> further mitigate any losses to those antennas.
> My hard line run to the tower from the shack is approx 800 feet. I
> have the cell flex hard line already. it goes from 1 1/4" down to the
> So 1 or 2 boxes? Any recommendations on size? any recommendations on
> manufacture/brand/terminal strips needed?
> A lot here and if some would like to comment and or add thoughts
> suggestions without tying up the reflector unless there comments help
> others please contact off line
> cpitts at ec.rr.com
> K5OF, Charles "Ed"
> TowerTalk mailing list
> TowerTalk at contesting.com
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