I was looking for a way to connect a home-made "cantenna" to my laptop's internal wireless card. I found this instructable: https://www.instructables.com/id/Dell-Laptop-WI-FI-High-Gain-Antenna-Mod-Increase-_1/ but as you can see, the author uses a SMA type connector, which projects from the side of the laptop case. I wanted a flush connector! After some research I decided to use a MMCX connector, but discovered this was unfeasable due to mounting issues. I discovered a bulkhead mounting for the slightly larger MCX connector, and decided to use one of these. You will need to be able to work fairly accurately at a fairly small scale to complete this project.
# 1. I found the wires and connectors for this project on eBay from this seller: xqv3000
# 2. After writing this instrucable I discovered that it is possible to get a MCX bulkhead connector which you can connect directly to the cable, such as these: http://www.amphenolconnex.com/SearchResults.asp?ProductID=57 or this http://www.rfconnector.com/mcx-bulkhead-crimp-jack-connectors.html, however I think I would still recommend using the F-F bulkhead adapter.
# 3. Unless you need to, use a straight, rather than right-angle connector for your external connection. I found that a right angle connector takes a lot of effort to get out.
Step 1: Obtaining the Parts:
You will need:
Bulkhead mounting MCX to MCX coupler (female to female)
MCX male to U.FL cable
Some kind of thick plastic to make a spacer out of (I used a bit of old car dealer signage I found)
Some sturdy metal plate (I used 2.5mm aluminium, but you could use steel)
2 small countersunk screws, either self tapping, or machine screws with nuts
Optional heatsink compound
Tools: pencil, ruler, drill, bits, pliers or small spanners, screwdriver, hacksaw, metal shears, round needle file, flat file.
Step 2: General Construction (bulkhead Connector)
The MCX coupler needs to be mounted on something solid, which in turn is mounted in the laptop case. I did this by drilling a hole in a piece of aluminium (but you could use steel) for the coupler, and a hole either side of it to take the two screws which will go through the case. The distance from this mounting plate to the laptop case needs to be 5mm or slightly less (it is okay for the coupler to project through the case slightly, but if it is inset the external connector may not lock properly - or at least the right angle one I used won't).
All holes for MCX coupler. Drill 3/16th's of an inch and file it slightly to get a nice snuggly fit. If only metric bits are available, 5mm is the size to use, but it will be a bit loose. 4.5mm would probably work but I haven't got one so I don't know.
Space between external mounting holes. 14mm. This just nicely clears the 8mm washer if you are using one. You could get away with 12mm but this might require a bit too much precision in your work. If you do reduce the measurement, remember you need some clearance for the screw heads!
Length of screws. If using self tapping screws, 1/2 inch or 12mm (this includes the head if they are countersunk screws). If using machine screws, add extra length for the nut and shake-proof washer.
Clearance to top edge of laptop case. The site chosen is under caps/number/scroll lock/wireless led's, but there is less space there. You need to allow about 3mm below the case edge.
Clearance to motherboard. You should allow about 1mm for the mounting plate. The plastic spacer(s) don't really need any clearance. If using the washer, it will nearly be touching the board.
I found that a small washer (internal diameter 6mm and external 8mm), plus a thickness of my found signage plastic gave me just the right thickness. For stability I made an 8mm hole in a second piece of this plastic and filed it down to the thickness between the mounting plate and the outer surface of the washer.
Step 3: Create a Drilling Guide/mounting Plate
This is the part where I went wrong, so I am describing this step here in order to save you from potentially making a mess of your laptop case. The site I chose for my socket, next to the external VGA socket, has an inner wall of thin steel. I don't know what kind of stuff Dell use to make this steel, but it seems to be exceptionally tough. If you do what I did, and drill through the plastic and rely on it to guide your hole through the steel, you may find that the holes end up bigger than you intended, and not where you intended either.
So the first thing to do is make the mounting plate for the MCX coupler and use this as a drilling guide. You can make it too big to start with and file it down when you actually need to use it as a mounting plate. It needs to be big enough to clamp to the outside of the case bottom.
Mark out on a piece of thick aluminium or not so thick steel, three centres 7mm apart, in a straight line. Drill small pilot holes (say, 1.5mm). Then drill out the centre hole to 3/16 inch, and the two outer holes to the inner diameter of the screws you intend to use (if self tapping) or the outer diameter (if machine screws).
Step 4: Preparing the Laptop
You need to strip the laptop down to the base of the plastic casing before attempting to make any holes in it.
Disconnect the AC supply and remove the battery
Fold the screen right back, then prise up the end of the plastic cover just below the screen, and gently remove it. It will seem like it isn't going to come off, but it will if you persist.
Next remove the keyboard. There are 2 screws which hold it down at the top, remove these and lift out the keyboard (you will have to unclip it at the edges). Release the keyboard connector by lifting the bar which holds the cable in place, and remove the keyboard.
Disconnect the wires which go into the screen - the two which fit the wireless card, the main screen VGA connector (just pull the blue tab, also undo the little silver captive screw next to it to release the ground wire) and the little white connector next to the wireless card.
On each side there are 3 screws which hold the screen hinges to the case. Whilst the screen is folded back, remove the screws which hold the hinges at the top, then raise the screen. Remove the two little screw covers at the ends of the back of the laptop case, , and remove the screws. Remove the two screws underneath the case and lift off the screen.
Turn over the laptop and undo all the screws underneath. Pop out the hard drive (note that it's securing screws are different to all the rest) and cd-rom drive. Undo the captive screw which secures the bit with the power switch on it to the base. Pull out the touchpad connector by it's blue tab. Unclip the top section of the case starting at the front (because there is a big clip at the back) and lift it off.
Undo the four screws which hold the heatsink to the CPU. They are numbered, and you should undo them a turn or two at a time, in the order of the numbers. Gently remove the heatsink. Observe the condition of the grey heatsink compound - if it is uneven you may consider replacing it when you replace the heatsink. Remove all the screws which secure the mainboard to the base of the case. The metal casing which surrounds the expresscard slot is also fastened to the base - undo the screws which secure it. There is no need to remove it from the mainboard. Lift out the mainboard and put it somewhere safe from static discharge and physical damage.
Step 5: Drilling the Laptop Case
Okay, this is the scary bit. It is also quite time consuming.
You need to work out a centre line for the holes you are going to drill. This needs to be a little over 4mm above the top of the motherboard and about 7mm below the top edge of the base of the case.
The top of the motherboard is roughly aligned with the hole in the plastic through which the external VGA socket projects, so use this as a measuring guide. Your centre line should end up roughly in line with the bottom edges of the top line of holes in the external VGA socket, and the inside edges of the tops of the USB sockets. Measure, measure, and measure again!
To use the site I chose, next to the external VGA socket, measure halfway between the two edges, and then 7mm each way out from there - then check that the distance between the outer marks is 14mm. Make centre marks to drill the 3 holes, then drill the two outer screw holes through the plastic outer case only. Line up the mounting plate with the holes you drilled in the the plastic, and clamp it firmly. Put the drill bit or a small screw through one end to stop it slipping. Drill the centre hole first, and use the drill bit to hold the guide in place whilst you re-clamp and drill the ends. The steel is very tough and thin, and will snag your drill bit, so proceed slowly and file it with a needle file when you've done drilling. You should end up with 3 neat holes in the right places (not like I did - I didn't use the drilling guide at first so my holes weren't in the right places). Don't drill your countersinks yet, leave that until you are ready to assemble the project. This will give you a slightly better error margin.
Step 6: Make the Spacers
You need a total thickness of no more than 5mm from the mounting plate to the inside of the case. The whole thing needs to be as stable as possible, as the MCX connectors take a bit of effort to insert and remove (I tested this on the weighing scales, it took 1.8Kg to push the connector home). For this reason I made spacers to match the mounting plate.
If you can find a piece of plastic of the right thickness, great! Drill matching holes, plus a counterbore in the centre hole to accommodate the flange on the connector.
In the absence of 5mm plastic found that a piece of 3mm (ish) plastic and a washer made just the right thickness, including the thickness of the flange on the connector. I cut and drilled two pieces of the plastic and drilled the middle hole in one of them out to 8mm to accommodate the washer (I used a step cutter for this - gives a very clean, big hole). I then filed down the thickness so that it could sit on the mounting plate with the washer in the middle being flush.
The washer isn't strictly necessary - I used it to get the right thickness. If you are confident you have the right thickness of spacers to start with, you can leave it out. Don't be tempted to use just the washer and nothing to space out the screws in line with it though, as this is added for stability.
Mark and file down the spacers so that they fit into the space, allowing 3mm clearance at the top and 1mm at the bottom. If using the washer, you will have to file right down to the hole. You may have to do this with the main board in situ so you can see how it fits.
Use fine sandpaper to remove rough edges, stray bits of metal etc from the plastic - you don't want any of this floating around inside your laptop!
Step 7: Cut the Mounting Plate Down to Size
Allow about 3mm between the outer holes in the mounting plate and the outer edges (using 2mm holes, this gives 2mm of metal on the outside. You may find you need more.). Trim the top and bottom edges so the whole thing is about 7 or 8mm high. If using self tapping screws, screw them into the mounting holes now so you are not straining the assembly when you assemble it, and then remove them. Ensure there are no stray bits of metal attached to the plate.
Step 8: Replace the Main Board
Ensure there are no burrs on the inside of the holes you drilled in the case.
Position the main board in the case and insert and tighten the screws. Ensure you don't put a screw in the hole for the bit which carries the power switch!
If you are going to replace the heatsink compound on the CPU, here's what you do.
Cut a piece out of a plastic bottle and use this to scrape off the grey compound from both the CPU chip and the heatsink.
Use nail varnish remover to clean off the remainder, and surgical spirit to clean up after that.
Spread a thin layer of new thermal compound on the copper surface of the heatsink. Ensure there is enough to contact the whole surface of the CPU.
Carefully position the heatsink back on the CPU, aligning the screws with their holes. Press down and gently twist it back and forth a little to bed it down on the new compound. Take extra care here as the heatsink has an arm which covers the GPU.
When you have replaced the heatsink, with or without new compound, tighten the four screws a turn or two at a time in the order of the numbers next to their holes, until the four screws are nice and tight.
Check carefully that you haven't missed any screws.
Step 9: Fit and Connect the Socket Assembly
Slide the spacers (and washer if using) onto the socket, and try to fit it in place. I say try, because you are likely to need to file it down a bit. Well done if it fits the first time!
Remember, you need 3mm clearance between the top of the mounting place and spacers, and 1mm between the main board and the mounting plate. If using the washer, there should be at least a thin layer of the plastic spacer between the edge of it and the main board.
Ensure the screws will go in cleanly. If not, this is the time to make any adjustments necessary. Remove the socket assembly and spacers.
Choose a drill bit with the same diameter as the screw heads, and use this to countersink the holes in the case. Drill slowly for this. If your drill has adjustable torque, choose a low setting. The bit is likely to snag, especially if the hole isn't quite round. If this happens you should stop immediately, take the bit out of the drill, and use it by hand to clear the snags in the hole. Go just deep enough for the tops of the screws to be flush with the case; so the shaft of the drill will go into the plastic just slightly.
Fit the spacers and socket assembly, insert and tighten the screws. Do not overtighten the screws as this could damage the case. If using self tapping screws, since you should have already screwed them into the mounting plate once, be careful not to cross thread them.
Push the MCX end of the pigtail into the internal side of the connector, and connect the U.FL end to the laptop's internal wireless card. The card has a main and auxiliary connector, however on mine they are not labelled. If you can work out which is the auxilliary connector, use that one - I believe it's the black one. Ensure the wire doesn't interfere with any parts.
Step 10: Reassemble the Laptop
Fit the top of the case back in place, starting with the clips in the middle at the back, and press the edges down all round. Ensure the trackpad connector is accessible.
Tighten the captive screw which holds the bit with the power switch, then turn the laptop over and insert and tighten all the screws apart from the ones which hold the cdrom drive and hard drive in place. Push the trackpad connector into its socket.
Fit the keyboard connector into its socket. It has a tiny tab at each end, locate these into their corresponding notches. Push down the top of the connector. Clip the keyboard into place and fit and tighten it's two screws.
Fit the screen into place, and insert and tighten the 3 screws at either end. Push the VGA connector onto it's socket, and fit and tighten the captive screw on it's ground wire. Push the little white 2 wire connector into it's socket next to the wireless card, and push the main (white?) antenna wire onto it's connector. Ensure all wires are in their channels.
Fold the screen right back, and fit the plastic hinge cover, starting at the left side.
Insert the cdrom drive and hard drive and insert and tighten their screws. Lastly, re-fit
Check you have no parts left over!
That's it. Enjoy your new antenna connection.