Grounding used at N1CC station:
No copper braid is used. Circulating currents at RF can be different on each strand in the braid, and you can have arcing
and high impedance crop up in the process, and that can defeat the mission of getting good RF ground, and not affect
DC and AC grounding, therefore it is difficult to detect problems.
The interface to the house:
MFJ feed panel is used in existing window in the shack. Inside the shack the 2” wide copper strip goes all the way
around the room to the station termination. On that strip inside the ham shack an Alpha-Delta 4 position grounding
switch is used to choose from three antenna feeds to the main operating position. LMR-400 is used from the MFJ feed
panel to the switch, and from the switch to the station transmitter/receiver interface. The wire to the rotor is through a
nylon feedthrough with plumbers duct seal used to seal out water and bugs.
House Terminations
The LMR jumpers from the window interface, using LMR-400 cables, connect to Alpha-Delta lightning arrestors. Each
line has its own arrestor and then a coiled LMR-240 18” jumper is used to go to a PL259 Barrel feed through in the
waterproof aluminum case where the end of the LMR-400 to each antenna is terminated. These feed lines go into a 4”
PVC conduit to the main tower, and one, the green cable goes to a 1/5” conduit to the 43’ DX Engineering Vertical about
88’ away from the house towards the NW. This vertical also has a ground rod and 30 radials buried in the ground. One
cable goes to the base of the tower (Red cable) for the beam some 300’ through the conduit along with the rotor cable
and five pull ropes for expansion. The remaining cable (white) runs 115’ to a riser where it comes out to provide feed to
a DC over coax (Bias-T) switch that chooses between the 80/40 Fan Dipole and the 160M Inverted L.
The 2” wide buss from the house connects to the insulated copper buss strip that interfaces the arrestors and the
ground copper 2” buss to an 8’ ground rod to the left of the junction box, then to another 8’ ground rod to the right, 15’
along the patio to a third ground rod at the end of the patio. The buss is bolted with stainless steel fittings and is
soldered. (The gravel in the bags has since been distributed along the ground so that weed whacking and lawn mowing
won’t disturb the lines.
At the base of the 160M Inverted L there is a ground rod and a Choke Balun from the cable to the feed point of the
Inverted L. The radials are 135’ long and elevated 8’ high. More radials and other work is still being created for this feed
point later.
Tower Base
This is the nearly completed tower base. Please not the Rotor cable lightning
arrestor mounted about 4’ above ground for serviceability. This effectively
protects the rotor cable run to the house from any strikes on the tower.
The identical junction box as at the house end (painted orange) brings all of the
cables in from the side in the 4” conduit, and then feeds out through a PL259
bulkhead and a Teflon feed through for the rotor cable. Total run to the beam
with a coil of reserve is 330’ of LMR-400, 250’ buried from the station junction box
to the tower junction box and then 80’ of LMR-400 to the balun on the Force 12 C3
antenna.
Each tower leg is connected above the concrete by a 1.5” copper strap to a 8’
ground rod off the edge of the tower base. No grounding goes into the concrete,
as that can take a hit, crack the base and make a nasty crash site out of your
installation.
I did not put the ground straps on until after this picture was taken. A 50’
diameter circle was made so that no trees were in the area where guy wires and
other access/egress would be present. The overall height of the tower is 64’.
Completed Tower
The guying of the tower uses 2 insulators per line to the tower, therefore the anchor
connections do not need grounding connections as they are RF/DC/AC isolated from the
tower and the anchor bases.
Proper termination and sources for grounding materials:
Georgia Copper
DX Engineering
DX Engineering
DX Engineering
DX Engineering
ABR Industries
Lowes
Lowes
DX Engineering
Copper Strap 25'
Ground Strap 50 ft
CU Bond Clamp
8 Wire Rotor Cable
12’ LMR-400
18” LMR-240
8’ Copper-Steel GR
Earth Ground Clamp
Anti Seize 4 oz
1310-025
DXE-CS2-50
DXE-58R-112s
DXE-CW8-HD
Cable Jumpers
LMR240, Adapters
5/8” Clamp
1.5 inch clamp
UMI-80071
1
1
2
300
6
4
8
3
1