DIY Reverse Polarity TNC plug and socket
Owners of Linksys WAP11 and other access points that use the same aerial connector may suffer the same problem as I did which is the lack of easy availability of RP-TNC connectors. Now before I go any further, you can buy them from Hyperlink Tech (USA) for starters:-
I bought an RP-TNC to N male cable 2 foot long from them and whilst the service and delivery was good, the cost of carriage to the UK was more than the cable assembly itself. The total was around $40 or £30 give or take a bit!
I have not found a UK supplier yet of the appropriate RP-TNC connectors, both RS Components and Farnell only do a fairly limited range of standard connectors but this got me thinking about how different normal polarity bits were compared with reverse polarity. This article shows how to reverse the components so that you end up with an RP-TNC plug and an RP-TNC jack and the best bit is that minimal tools are required and about 30 minutes of time. (If anyone does find any good sources of RP-TNC connectors in the UK please let me know.)
Sharp knife (just a basic craft knife, nothing special)
Small file (optional but helps tidy things up a bit)
Electric drill (I used a standard household drill, my dremel tool didn't have a suitable chuck but if you have one, try it. A modelling lathe would be luxury!)
TNC Plug (RS Components) part number 193-8186 (cost £2.78)
TNC Jack (RS Components) part number 382-1513 (cost £2.13)
Slightly cheaper ones are available
(click any picture to enlarge)
Lets take a look at the components, here's the jack
and here's the plug
Taking a closer look at the insulators, side by side, you'll see that the dimensions are the same across the base, the length is also the same, the only difference is the size of the shoulder from the base! On the left is the part that we want to modify, this will become the insulator for the RP-TNC plug, the other part remains unchanged.
Here are my tools, not exactly rocket science! :-)
Mount the insulator from the TNC jack into the drill as shown and using the knife in the same way as a lathe tool, carefully work the knife along the insulator with the drill running (I'd hope you would have realised that bit!). In case it's not clear, hold the knife horizontally i.e. with the blade horizontal with reference to the picture, not vertically. We want to cut down the width of the shoulder, not a lump off the end.
When finished it should look something like this:-
Enlarging the two insulators, they should look like this, remember there's no need to do anything to the insulator from the original plug. You'll notice that the shaft of the left hand part is a little rough. This doesn't matter as it is not a mating part, the rough part sits inside the metal shroud of the connector.
That's it! Yes really - that's all there is to it! Now use the modified insulator and the metal socket that receives the mating centre contact with all of the standard plug components. You might need to reduce the size of the diameter of the base a fraction. When I say a fraction, I just ran my flat file around the plastic just once and lightly at that. It then fitted into place perfectly.
All I was after was the RP-TNC plug and the next picture shows the end result, looking end on to the new RP-TNC plug. Optionally you can use the insulator that was never changed, with the centre pin in what was the original plug to make an RP-TNC jack, if you want this part the you will probably find that you need to use a 6.5mm drill to open out the shell of the plug to allow the insulator from the plug to fit properly.