Building Ronja Signal Cabling

What we are going to build

We are going to:

Build one 1.5 meter long power exchange cable (W2-PWR)
Build one 0.6 meter long RSSI cable (W5-RSSI)
Equip the signal cables(s) (W1, W2, W5) with connectors (W4).
Attach a W3-PROT lightning protection cable attached to W2-PWR.

Purpose of the cables

Power exchange cable (W2-PWR) allows both optical heads to share electrical power. The optical heads take electrical power from shields of the signal cable(s). Shield of RX signal cable (W1-RX) carries +12V and the shield of the other signal cable (W1-TX) carries 0V (Ground, GND).

All connectors within Ronja 10M Metropolis system are made of pieces of thick copper wire (W4). The female is made from electrician's wire nut. The connector is being secured by tightening a screw. This system ensures reliable contact. This system also ensures small width of the installed connector male so signal cable can be pulled through holes when laying in building (through-wall holes) and installing inside the heads (pulling through holes in the lids) with connectors (W4) attached. This eliminates the need to perform soldering on the roof.

A variant to soldered connector would be a crimp-on, but according to my experience, they are highly unreliable, especially in outdoor installations. They also require special (expensive) pliers for mounting.

W3-PROT lightning protection cable protects your home electric installation from a fire hazard if lightning strikes directly into the shield of signal cables (W1) laid on the roof. The undefined contact between the RX and TX shielding case and the tubular heads' metallic case cannot ensure reliable protection of in-house electrical installation from absorbing the lightning energy and setting the house on fire.

Cutting

Cut the following wires:

Designation	Number of pieces	Length	Thickness (crosssection area in mm^2)	Solid Wire/Stranded	Insulated	Shielded	Number of (inner) conductors
W1-TX	1	Distance from PC to intended optical head mounting site		Any	Yes	Yes	1
W1-RX	1	Distance from PC to intended optical head mounting site		Any	Yes	Yes	1
W2-PWR	1	1.5m		Any	Yes	Yes	1
W3-PROT	1	1m	1	Stranded	Yes	No	1
W4-STUB	16	29mm	4	Solid Wire	Any	No	1
W5-RSSI	1	0.6m		Any	Yes	Yes	1

Postscript / PDF / EPS / BIG png / SVG (Inkscape)

Stripping

Strip all the wires:

Wire insulation ID	Length
W1, W2, W5 outer insulation	29mm
W1, W2, W5 inner insulation	4mm
W3-PROT	10mm
W4	Remove all insulation

When stripping the outer insulation, take care not to cut the thin wires of the shields.

Strip 10mm off W2-PWR outer insulation in the middle, so that the shield becomes accessible.

Covering with solder

Twist all visible stranded copper up. Cover the ends of the conductors with solder:

Wire ID	Length of solder coverage
W1, W2, W5	4mm
W3-PROT	10mm
W4	4mm in the middle of the stub

Cover the stripped place in the middle of W2-PWR with solder too. Solder up one end of W3-PROT to this place.

Postscript / PDF / EPS / BIG png / SVG (Inkscape)

Ends

Solder eyelet on the single end of W3-PROT. Solder stubs (W4) on all free ends of W1, W2, and W5 according to the drawing.

Conductor designator	Colour	Function
W1-RX shield	Red	+12V
W1-RX inner	Blue	Signal
W1-TX shield	Black	0V (GND)
W1-TX inner	Blue	Signal
W2-PWR shield	Black	0V (GND)
W2-PWR inner	Red	+12V
W3-PROT	Black	Earth protection
W5-RSSI shield	Black	0V (GND)
W5-RSSI inner	Blue	RSSI voltage

Insulation

Wrap up (insulate) the soldered joints with coloured duct tape according to the table. Use enough tape to reinforce the ends of the cable mechanically too (to prevent it from breaking off during repeated bending).