cisco-aironet350 modification

Andrew Spurrier and John Samin VK1EME

Step 1.

This was the first card modified so we were a tad carefull... First we removed the cover off the transmit end of the PCMCIA card. It actually came off very easily, using my fingernail, you just need to get something under the cover and prize it off. It his held on with some sticky stuff that seems to stick back on quite well.
From the diagram you can see there are a couple of LEDs an antenna jack of some sort and a hole that shows a barcode from the internal PCB. Don't know what kind of antenna jack it is though it may be OK to use if you can get a connector for it. Most probably it is used for testing the unit. We couldn't get the plug, so surgery IS the only option.

Step 2.

A lot of thought went into opening this baby up, it had to be neat and precise - the PCMCIA card is delicate! In the end we decided to do it with a modified Soldering Iron. Just sharpen the tip with a file, so it is like a small hot knife. Have a look!

This is a 12 volt Soldering Iron with removable tip. It was filed down to around 1mm thick. If you file it too thin it will bend. This happened, but the second attempt was better because the tip was wider. We attached the Soldering Iron to an adjustable 12volt power supply. Around 8volts was good, it didn't burn the plastic and it cut really well.

Step 3.

Ok Doctor it's surgery time!! First we opened up a little bit of the case, and took a peek, there were no components (or sardines) around so we opened up the whole thing, cutting just inside the edge so that the cover could be glued back on. The Solding Iron worked very well.

Step 4.

Once we opened up the case it was obvious that this card could be modified to accept an external antenna. In the picture above, just under the "Tracks to be Modified!" text, there are tracks that have been etched to accept another antenna jack. All that has to be done is cut the track to the biscuit antenna, rub off the green PCB coating from the ends of the track and solder on some minature coax. It may be a little hard to see in the picture, and these tracks are small so take great care! We used a hobby knife to cut about 1mm of the track just where it joins the antenna. It's much easier to see in the close up (below).

Step 5.

Solder on the minature coaxial cable. Use a very short length, this stuff is very lossy! Again you will be working with very small tracks, don't use too much heat or you may lift the track and stuff the whole thing...

The PCB track etching is the same on both sides. You can see how the center track on the left side is connected to the antenna. We cut the track (on the right hand side) just where it meets the antenna. We also cut out a channel for the coax to exit the case once the lid was back on.

Step 6.

The coax is a little to high to allow the cover to sit back on properly. We decided to put some heat shrink over the end to hold it on neatly. Before you shrink the plastic tube, wrap all exposed areas of the PCMCIA card in aluminium foil, use around 10 layers of it. The card probably won't want to be cooked in the process. Do the same to the coax pig tail, or the plastic coating will melt. Once the heat shrink was on, use a slightly moist cloth to absorb the heat away from the PCMCIA card.

This picture is of the second modified card - BEWDIFULL! And of course the second one was a lot easier... Notice the cable output is offset, we took the cable out from the middle in the first card and this made the soldering more difficult. Also the surgery wasn't so brutal in this one. We measured around the tracks, about 10mm square and cut this section out only. The track etching is symmetrical, so measure around the antenna jack you can see, and apply this to the other side. We made a small channel for the cable to exit though.