RP-SMA pigtail in T23

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DooMinick · #1 Post by **DooMinick** » Tue Apr 17, 2007 6:02 pm

I've been searching the web (and this forum of course) if someone already installed the RP-SMA pigtail in T23, and no result. Now this weekend I'm going to do it in mine T23, and I'd like to ask if someone has any idea, how to put it, considering following limitations:
-not to stand out more than 1mm at the back (thus docking would be possible and it wouldn't accidently break)
-have place around to tighten the external antenna cable
-pigtail length is about 15cm

The RJ-11 socket can be removed, I don't look forward to use it anymore (rather buy some PCMCIA modem for special occasions).

I'm not going to use it with a stick external antenna (like in routers +3dBi, +5dBi etc...), but from time to time I want to connect an external directional antenna to establish some longer distance link. There would be a second, internal antenna mounted somewhere inside the laptop (I can't decide where).

I see two options, one is to mount it somehow between the VGA and RJ-11, but the same way as all D-Subs are mounted. It would take to cut a rectangle between VGA and RJ-11 and stick it deeper, extending that deeper place where D-Subs are. The second option is to use the place of RJ-11 socket and make a mechanism similar to the Xjack antennas, that would keep the RP-SMA hidden when not in use, and expose it when needed. That would be very tough, I think.

Every idea would be appreciated, maybe some pictures or drawings. I've already seen Ray's 600X, but it's no use for T23.

#2 Post by **rkawakami** » Tue Apr 17, 2007 6:19 pm

Welcome to thinkpads.com!

Actually there is a thread about adding a pigtail to a T23:

I have 18 WIFI cards, this is my best wifi receiption ever

Although I don't think that you will be able to meet the 1mm extension out the back. As you have seen, the place where I put my RP-SMA connector on the 600X is on the side, where it would not interfere with a docking station. There does not appear to be any such place on the T23.

If you can consider a different type of connector then it might be possible to mount sometime on the side or at the back without sticking out too far. You would have to research all of the different types of miniature RF connectors.

As far as the internal antenna, there is also this thread:

T23 Internal Wifi Project

DooMinick · #3 Post by **DooMinick** » Tue Apr 17, 2007 6:37 pm

Thanks, I've read these already, your article is great, but I still think of some place to put an internal antenna. Well, that's not the main case here.

The first link you've given leaves the problem unsolved. For me, the docking station problem is even less important than the fact, that the standing out connector could be easily damaged (look at used iSeries IBM's, majority of them have broken D-Subs).

When I just get my antenna shipped (bought it today on polish equivalent of eBay) I'll disassemble my laptop and have a closer look.

I just thaught about the place on the left side, symmetrically to your 600X, near the CPU fan grill.

#4 Post by **rkawakami** » Tue Apr 17, 2007 6:41 pm

Between the CPU fan/heat sink and PCMCIA cage? Don't think there's enough room for an RP-SMA. Same thing if you mean between the CPU and the rear panel. There's an inductor in that location.

DooMinick · #5 Post by **DooMinick** » Tue Apr 17, 2007 6:48 pm

rkawakami wrote:CPU and the rear panel. There's an inductor in that location.

Yes, that's what I thought about. Like the mirror of your 600X. I wonder, why IBM forgot about the place for an optional RP-SMA...

edit: the green marked places on this picture are the places I'd like to have RP-SMA the most. I hope, you don't mind using your photo, but if so, just tell me.

#6 Post by **rkawakami** » Tue Apr 17, 2007 7:30 pm

I suppose you could remove either the PS/2 or S-Video connector and put the RP-SMA connector there. It's something that I saw done with a 600-series system before I did my 600X (it's referenced on my page). I believe both connectors are mounted on the T23's I/O card so you have to remove the motherboard and pull that card out. There may be room to mount the RP-SMA pigtail on the back panel but you still have the same problem with that type of connector. Since it has external threads and a female connector, you need about 4 or 5mm exposed so you can twist on the antenna or cable. That would probably interfere with a docking station or port replicator (unless you cut out the plastic).

There are smaller RF connectors but they do not have the lifespan of the RP-SMA. For example, MMCX are push-on type connectors but they are considered very fragile. They are meant for minimal connect-disconnect cycles. They would be great for this type of application (flush mount and small in diameter) but if you are going to be plugging and unplugging a cable or antenna, you may eventually wear it out.

re: the picture; not a problem.

The area behind/below the video ribbon cable where you have indicated is a place where I have considered putting the internal antenna. I believe it's the same place where Spirit-1776 mounted the RP-SMA but has indicated that it will not clear the dock.

DooMinick · #7 Post by **DooMinick** » Tue Apr 17, 2007 9:08 pm

rkawakami wrote:There are smaller RF connectors but they do not have the lifespan of the RP-SMA. For example, MMCX are push-on type connectors but they are considered very fragile. They are meant for minimal connect-disconnect cycles. They would be great for this type of application (flush mount and small in diameter) but if you are going to be plugging and unplugging a cable or antenna, you may eventually wear it out.

Thus no good for me, I've already had MCCARD connector on my Orinoco and I know it's not, what I'm looking for.

The area behind/below the video ribbon cable where you have indicated is a place where I have considered putting the internal antenna. I believe it's the same place where Spirit-1776 mounted the RP-SMA but has indicated that it will not clear the dock.

And so after I disassemble my T23, I'll look for a way to extend that deeper space, where VGA etc is mounted, by cutting some plastic and trying to mount the RP-SMA in-line with VGA, on the same depth, so it shouldn't stand out more than 1mm and there would be enough space around it to manouvre with fingers to tighten the cable on it.
Of course I'm aware, that the inverter tape could be the limit and some reinforcement of that place should be made after cutting that rectangle between the deeper space with VGA and RJ-11.
I don't have a digital camera at the moment, but if I succeed, I'll post some pictures made with a webcam. Better than no pictures at all...

#8 Post by **RealBlackStuff** » Wed Apr 18, 2007 1:58 am

Not knowing how big this thing is, have you considered the space at the front-left, between the hard disk and under where the left lid-slider pops in?
As seen from the front, it is partly angled inwards away from the front. The RP-SMA could stick out there minimally if required, without interfering with a docking station.

DooMinick · #9 Post by **DooMinick** » Wed Apr 18, 2007 3:57 am

No, because as I mentioned in my first post, the pigtail length is only 15cm. Secondly, it is about 5mm long behind the mounting wall, until the cable can be bent. And after all, in some situations it would be very uncomfortable to have thick H-155 or even H-1000 cable faced towadrs me:)

DooMinick · #10 Post by **DooMinick** » Wed Apr 25, 2007 5:24 pm

Finally, I've got all I need to finish the job. My T23 is disassembled on the table and I 've just made some photos (very poor quality, webcam) of what I'm going to do and I'd like some comments about it.

The first picture is the upper view and the red line is how i'd like to do a mounting wall for the RP-SMA, but the question is, if that metal plate is a crucial thing (including it's part at the back, vertical) or if I can deal without it. I understand it's a screen which holds electromagnetic interferences out of the LCD tape.

The second photo is just a different angle view, also red lines show, what I'd like to do.

Finally, the third photo shows, what big hole I'd like to make at the back (and after that rebuild the wall a bit deeper, leaving no extra holes).

All comments and suggestions are welcome, if you need some extra pics. just tell me.

#11 Post by **rkawakami** » Wed Apr 25, 2007 6:24 pm

DooMinick wrote:The first picture is the upper view and the red line is how i'd like to do a mounting wall for the RP-SMA, but the question is, if that metal plate is a crucial thing (including it's part at the back, vertical) or if I can deal without it. I understand it's a screen which holds electromagnetic interferences out of the LCD tape.

The Hardware Maintenance Manual describes it as an ESD (electrostatic discharge) bracket. I believe I ran a T23 without one for awhile and did not notice any problems. If I remember correctly, it has since been replaced. Not sure what is being protected from the static discharge. From memory, the bracket slides over a portion of the metal framework in the base of the system. The LCD ribbon cable then sits on top of it. So in effect, the LCD cable (and whatever else it's connected to) may be protected from any static build-up by being grounded to the base of the system.

DooMinick wrote:Finally, the third photo shows, what big hole I'd like to make at the back (and after that rebuild the wall a bit deeper, leaving no extra holes).

How/what are you going to use to rebuild the wall? Aluminum flashing?

DooMinick · #12 Post by **DooMinick** » Wed Apr 25, 2007 6:49 pm

I'd use the rectangle of plastic cut from the back plus epoxy with glass fibre (I've used that epoxy in my car after cutting some very rusted part of steel about 20x15cm, and when I got hit in that place by another car, it wasn't even scratched, unlike steel near it).

I've also found, that there is enough place to fit the RP-SMA the way you did in your 600X, but on the left side, between the CPU fan and rear wall. I should consider it, even if it took to cut a little bit of LCD bezel (that wich goes deeper there).

TomKroscavage · #13 Post by **TomKroscavage** » Wed Apr 25, 2007 10:03 pm

I have been trying to find time to make the connector spring loaded so just a few threads stick out until you screwed the antenna on and it would drawl the connector out. the pigtail would need a stop inside the laptop.
My solution for docking was to make a neat slot in the dock itself. Crude I know, but I have stellar wifi.
I have an aux. antenna under the keyboard for when I don't need the external antenna.

DooMinick · #14 Post by **DooMinick** » Thu Apr 26, 2007 3:27 pm

So the operation is done. I've changed my previous plan and after speaking and watching the sub card with my dad I've decided to put it in the drilled RJ-11. However, even drilled with 10mm drill (and that's hard to drill in the RJ-11 mounted on a fragile sub card) it still remained too small (or just had a bad inner shape, if I would play for a few hours with a small, sharp knife, it would fit there). So the only way was to cut the upper and left walls of the RJ-11. The hole in the back wall was drilled with 6mm drill.

The pictures show it from the inside and from the outside. Once more I apologise for my poor webcam, but these pics may be useful for someone to decide, if this would be a good place for him.

I've tested it with my D-Link700AP antenna, and it fits perfectly.

Waiting for comments and critics.

TomKroscavage · #15 Post by **TomKroscavage** » Fri Apr 27, 2007 6:52 am

Can you screw an antenna on?

danage · #16 Post by **danage** » Fri Apr 27, 2007 8:45 am

looks like a nice idea to me. somewhat fragile though. i would have probably tried to use hot glue and removed the rj-45 connector in its entiety to get a more stable foundation for the coax connector.

DooMinick · #17 Post by **DooMinick** » Sat Apr 28, 2007 11:56 am

Spirit-1776

Yes, I can, I just wonder how it will be like with a cable, but that I'm gonna find out in practice.

danage

It's not as fragile as it looks like. After doing this I've screwed the antenna on and tried to shake it (with a reasonable force of course) and nothing moved or cracked or anything like this.

Anyway, If this won't be useful in practice, my next idea is to try mounting it with a machanism of an old radio button on/off with a spring. It would be the best to have it outside when needed and inside when not in use.

I forgot to mention that after putting the lap back together I noticed that one of the screws holding the hinge cover cannot be screwed in this setup.

RP-SMA pigtail in T23

RP-SMA pigtail in T23

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