All:
 Original article from: Wayne Sarosi 
 Reposted by Rob Dennis,Moderator HAM_TECH,for use of the FIDO HAM_TECH echo.
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SUBJECT: Radio Shack Design - Part 4
RF Distribution.
 Your RF distribution system should be designed as simple as possible.
 For an example,I will use my antenna system. These will be antennas existing
and to be installed (if I get the time to climb.)
Inventory,top down:
 o (50 feet) 2m MARS Digi Co-linear vertical antenna.
 o (48 feet) 500-1300 MHz LPDA,horz. 37 elements
 o (46 feet) 67cm 10 element yagi,vert.
 o (44 feet) On cross-bar; left: 2m LPA 10 element,vert.
                          right: 2m Yagi 9 element,horz.
 o (43 feet) Rotor: Aliance
 o (42 feet) HF LPDA 13.5-28.5 MHz 10 element,horz. (Shaft drive)
 o (40 feet) tower platform; Alpha Delta DXA (40m,80m,160m)
 o (36 feet) On cross-bars; left: UHF TV yagi with corner reflector,RS Rotor
                           right: Discone 140-1400
 o (30 feet) 49 MHz vertical dipole
 o (25 feet) On cross-bar,on service tower; left: 2m J-Pole,vert.
                                            right: 1/4 wave 67cm,vert.
 o (23 feet) On service tower; (88-108)FM 300 ohm dipole,horz.
 o (8 feet) 2S1 Mobile or 96" whip or A-99 at S.E. corner of house with
                                           Roof Flashing as Groundplane.
 o (3 feet) Tail-Twister Rotor
 o Central Ground
 There are 18 separate input lines to the shack!
 A Wiring Nightmare,Batman!
 All is not lost.
 Use good rotor wire like Belden,good coax like 9913 and RG-214/RG213 and
there won't be any problems.
 RG-8 is good also for the low bands and can handle the high power.
 I would use RG-8m for the low power apllications and RG-58 for jumpers and
receive only. RG-59 with pre-amp or RG-6 for the UHF TV. The ground should be
in the range of 6 to 8 gage solid conductor copper wire. It should be 
ttached
from the base of the tower to the ground rod and run into the shack for a
common ground. This makes a common ground.
 The ground rod should be next to the tower (previous posting).
 OK,you have 18 lines to consider.
 This is not the norm; my tower configuration is anything but normal,but with
this insight,your RF distribution system may be much easier to handle or 
aybe
more difficult .
 Looking at what I have to deal with I must first consider the ground.
 I'll run that low out of the shack,directly to the ground rod.
 Next,I need to consider the 17 other cables coming into the shack.
 Three of these lines are Rotor control cables. The will be going directly to
the rotor with one exception.
 Each will have a MOLEX connector installed approximately four feet after the
entry to the shack,at the RF panel. Why? Disconnect it and the lightning has
no path to your rotor controller or AC power via the rotor cable.
 It also makes for easy service or relocation.
 There are 14 other cables to consider. These are all coaxial. Let's 
liminate
one; the UHF TV coax. It's under the big LPDA and static dispersion will
handle most of the protection from lightning.
 Run the RG-59 or such to the TV. Disconnect when lightning is in the area
or the TV is not in use.
Continued next posting.
-WS
--- GoldED 2.42.G1219
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