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XCOM Education Centre

Welcome to the XCOM education page, hear you will find handy information like how to make a wiring harness, the correct method for terminating a BNC connector etc....

Please check that often as this page will be under constant revision based on the questions and feedback coming from our customers.

How to quickly check out the XCOM Harness PDF ONLY 
XCOM Aerial Dummies Guide PDF ONLY

The correct way to wire an aircraft (link to further down page)

How to Make A Harness (link to further down page)

How to terminate a BNC connection (link to further down page)

What is the best aerial cable length (link to further down page)

How to Solder (link to further down page)


The correct way to wire an aircraft

Download this diagram in PDF format for easy colour printing Click here to download


How to Make A Harness

This section will lead you through the process of making a harness to suit the XCOM

Making a harness is more than a few hours work so if you don't have the time or skills then purchase a factory made harness from here or perhaps your local avionics shop can make one for you. However, if you have the time and would like to tackle the job yourself then the following information will be of assistance.

A lot of the parts needed to make a harness are also difficult and time consuming to source so we have special harness packs available from the ordering section with wire, switches and headset jacks to suit most aircraft. Please order from here.

This is a big page with lots of photographs so please be patient

  • Clicking on the smaller images will open a larger photograph
  • For later reference, this page may be printed out from this link PDF format 160K

Harness Preparation

Firstly, clear the bench and give yourself lots of room. Some harnesses can become big and heavy and you can never have too much room.  As you will soon find, you will soon have a mass of with wires going in all directions.

Wire and Fittings

Only use good quality Teflon wire (known as Tefzel). Do not use automotive wire for this job. You will require the following items:

  • Single core Tefzel 18 gauge for the power supply
  • Single core Tefzel 22 gauge for general wiring
  • Single core shielded Tefzel 22 gauge
  • Triple core and shielded Tefzel 22 gauge
  • Headphone and Mic jacks (2 sets if your plane is a 2 seater)
  • PTT switches (2 sets if your plane is a 2 seater)
  • Backlight On/Off toggle switch
  • Intercom On/Off/Isolate Switch
  • 3.5mm mono audio jack (if fitting music system)

Tools

Clear the bench and give yourself lots of room.  Now that the bench is clear get your tools ready.... Use a proper soldering iron made for the job. Do not attempt to solder small connections with a large soldering iron because it will not work - you will simply end up with large clumps of poorly connected solder. Use good quality solder and have lots of heatshrink ready.

Prepare the Heatshrink for the job. You will need three sizes for the harness - 1.5mm for the individual wires, 3mm for things like the headset jacks and multiple wires and 12 to 15mm for the bundle of wires coming from the DB15 plug.

Use good quality wire cutters like those shown. Tefzel wire is amazingly tough and the cheaper cutters won't do the job.

Power and Ground Wires

Cut the power and ground wires from the 18 gauge wire

Power = Red wire 400mm or as required in your plane

Ground = Black wire 400mm or as required in your plane

Strip and pre solder each end of the wires. This is consistent throughout the job. If necessary, cut the plastic back to expose the wire a little longer than required, solder the wire and then trim the wire to the exact length

PTT Wires

Cut the PTT wires using 22 gauge single core shielded wire

Standard PTT harness length is 1400mm or as required in your plane

Strip about 40mm from both ends and separate the shield from the cores by separating the mesh and bending the wire through the hole. We use a small screwdriver to assist

Try not to damage the shield during this process

On one end only, trim the shield to around 10mm and attach a piece of black wire about 50mm long

Solder and heatshrink over the section.

Trim the black wire to the length of the core, strip the shield and pre solder.

Pilot PTT soldered and heatshrunk

If the aircraft is a two seater you will need to make 2 PTT wires

Headset Wires

Cut four Headphone extension cables from 22 gauge wire about 120mm long. Strip and pre solder both ends

Cut the main Headsets wires using 22 gauge 3 core shielded wire

Standard harness lengths 1000mm or as required in your plane

Strip about 40mm at one end and separate the shield from the 3 cores and pre solder the wires

Strip about 100mm from the other end and separate the shield from the core. Trim the shield to about 10mm and add 2 x 120mm long black wires to the shield (headphone extension wires mentioned above). Cut off the same length as the cores, strip and pre solder

Separate the White wire and one of the Black wires which are used on the headset jack. The Orange and White, the Blue and White and the Black are used on the Mic jack. Heatshrink as shown.
Pilot Mike jack, soldered and heatshrunk
Pilot Headphone jack soldered and heatshrunk

If the aircraft is a two seater you will need to make 2 Headset wires

Speaker Wires

Cut the speaker wire from 22 gauge 1 core and shield 400mm long or as required in your plane

Strip about 40mm from both ends and separate the shield from the cores. On one end only, trim the shield to around 10mm and attach a piece of Black wire about 50mm long. Solder and heatshrink over the whole lot. Trim the black wire to the length of the core, strip the shield and pre solder

Backlight Wires

Cut the backlight wire from 1 core and shield

Standard length 400mm long or as required in your plane

Strip about 40mm from both ends and separate the shield from the cores. On one end only, trim the shield to around 10mm and attach a piece of black wire about 50mm long. Solder and heatshrink over the whole lot. Trim the wire to the length of the core, strip the shield and pre solder. Attach to the toggle switch and heatshrink as shown.

Music Input

Cut the music input wire from 1 core and earth

Standard length 400mm long or as required in your plane

Strip about 40mm from both ends and separate the shield from the cores. On one end only, trim the shield to around 10mm and attach a piece of black wire about 50mm long. Solder and heatshrink over the whole lot. Trim the black wire to the length of the core, strip the shield and pre solder

Attach the 3.5mm audio jack to one end

Note: The XCOM is mono only so do not wire for stereo sound

Intercom On/Off/Pilot Isolate

Cut the Intercom On/Off/Isolate lead from 3 core and shield or use three separate wires.

Standard length 400 mm long or as required in your plane.

Strip about 40mm from both ends and separate the shield from the cores. Cut the white wire from both ends as we only need the 2 cores and shield.

On one end only, trim the shield to around 10mm and attach a piece of black wire about 50mm long. Solder and heatshrink over the whole lot. Trim the black wire to the length of the other cores, strip the shield and solder to the toggle switch

Chassis Grounding Strap

Cut the XCOM chassis ground strap from black 18 gauge wire.

Standard length 300mm long or as required in your plane.

Strip and pre soldier the ends. On one end only, solder or clamp the earth fitting which is screwed into the back of the XCOM.


Harness Assembly

DB15 plug viewed from back

Clamp the DB 15 plug securely and pre solder the pins. The pins are numbered left to right on the back starting top left corner as number 1 and continuing the top row to number 8. The bottom row is 9 to 15.

Solder the Red power wire to pin 9.

Solder the back switch power to pin 10 and then bridge pin 9 to 10 with an off cut f wire or a small blob of solder.

Heatshrink both pins together (if you want backlight ON all of the time and no switch installed, then run a wire from Pin 8 to pin 10 and bridge to pin 9).

Solder the backlight switch to pin 8 and Heatshrink.

Solder the Black power wire to pin 12 and piggyback a 50mm length of black wire to the pin to act as a common earth for the rest of the harness and than Heatshrink.

Solder the speaker wires to pin 15 and pin 4 and Heatshrink.

Solder the music input to pin 2 and the common earth.

Solder the intercom switch to pin 5, pin 11 and the common earth and then Heatshrink all connections.

Solder in the pilot headset and mic wires. The white wire connects to pin 14, the orange and white striped wire connects to pin 1 and the blue and white connects to pin 7. Extend the pin 7 wire so that the pilot PTT core can piggyback and attach the Pilot PTT core wire. Heatshrink the wires and attach the earth to the common ground.

Solder in the co pilot headset and mic wires. The white wire to connects to pin 13, the orange and white striped wire connects to pin 3 and the blue and white wire connects to pin 6. Extend the pin 6 wire so that the co pilot PTT core can piggyback and attach the Copilot PTT core wire. Heatshrink the wires and attach the earth to the common ground.

Link up all common earths and solder in the black radio chassis ground.

Heat all heatshrink and fit the DB15 plastic shell

That's it ! You've finished you're new harness and are ready to test !!


How to terminate a BNC connection for your Aerial

Step one. Slide rubber boot and the crimping barrel over cable.

Step two. Cut end of the cable evenly and strip back 19 mm (3/4”) of the outer sheath.

Step three. Fold back the braid and cut away 5 mm (1/4”) to expose cable core.

Step four. Crimp gold pin over cable core.

Step five. Fold back braid to allow room for plug to be pushed over the gold pin, push all the way until the gold pin fully seats in the plug. Normally a clicking sound will be heard when the pin has been seated all the way.

Step six. Fold gold braid forward towards the plug and slide metal barrel over braid.

Step seven. Crimp with the proper tool.

Step eight. Slide rubber grommet over plug to finish the job.


What is the best aerial cable length ??

Well its all a bit of witchcraft and nonsense to me but our engineer has given me the following advice.... Try to get customers to cut their aerial cables to these optimum lengths.

Suggested aerial cable length in Meters

Suggested aerial cable length in Feet


How to Solder

What is Solder ?

Solder is an alloy (mixture) of tin and lead, typically 60% tin and 40% lead. It melts at a temperature of about 200°C. Coating a surface with solder is called 'tinning' because of the tin content of solder. Lead is poisonous and you should always wash your hands after using solder.

Solder for electronics use contains tiny cores of flux, like the wires inside a mains flex. The flux is corrosive, like an acid, and it cleans the metal surfaces as the solder melts. This is why you must melt the solder actually on the joint, not on the iron tip. Without flux most joints would fail because metals quickly oxidize and the solder itself will not flow properly onto a dirty, oxidized, metal surface. The best size of solder for electronics is 22swg

Soldering Basics

Obviously never touch the element or tip of the soldering iron, at around 400°C they are VERY hot and will give you a nasty burn.

Take great care to avoid touching the power cord with the tip of the iron.

The iron should have a heatproof power cord for extra protection, ordinary power cord will melt immediately if touched by a hot iron and there is a serious risk of burns and electric shock.

Always return the soldering iron to its stand when not in use.

Never put it down on your workbench, not even for a moment!

Work in a well-ventilated area.

The smoke formed as you melt solder is mostly from the flux and can be quite irritating. Avoid breathing it by keeping you head to the side of, not above, your work.

Wash your hands after using solder. Solder contains lead which is a poisonous metal.

Preparing the soldering iron

Place the soldering iron in its stand and plug in, the iron will take a few minutes to reach its operating temperature of about 400°C.

Dampen the sponge in the stand.

The best way to do this is to lift it out the stand and hold it under a cold tap for a moment, then squeeze to remove excess water. It should be damp, not dripping wet.

You can check if your iron is ready by trying to melt a little solder on the tip.

Wipe the tip of the iron on the damp sponge. This will clean the tip.

Melt a little solder on the tip of the iron. This is called 'tinning' and it will help the heat to flow from the iron's tip to the joint. It only needs to be done when you plug in the iron, and occasionally while soldering if you need to wipe the tip clean on the sponge.

You are now ready to start soldering

Hold the soldering iron like a pen, near the base of the handle.

Imagine you are going to write your name! Remember to never touch the hot element or tip.

Touch the soldering iron onto the joint to be made. Make sure it touches both wires. Hold the tip there for a few seconds and feed a little solder onto the joint.

It should flow smoothly onto the wires. Apply the solder to the wires, not the iron.

Remove the solder, then the iron, while keeping the joint still.

Allow the joint a few seconds to cool before you inspect the joint closely.

It should look shiny and have a ‘nice’ shape. If not, you will need to reheat it and feed in a little more solder.

Now practice....


Mobile 1 Aerial Plot


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