There had been rumors of an antenna jack lurking beneath the antenna of the USR2410 PCMCIA 802.11b card, so I decided to see what was really under the covers. This is a very cheap ($35 after rebate) Prism II based card which is useful in conjunction with the many WiFi utilities available in Linux. While it's a great bargain, the card's utilities are not very sophisticated, and its sensitivity leaves much to be desired compared to the ORiNOCO line.
The FCC ID is LLM002 WL11000-1, which shows that it's really an Eumitcom WL11000. It seems that Eumitcom has been bought out by Accton Technologies, and but although Accton has given it a new part number, the product is identical. The FCC has a goldmine of information about the WL11000 on their site, including schematics, photos of the inside, etc. Click here
There are multitudes of other Prism2 cards on the market which are identical, from vendors such as SMC, Siemens, Belkin. I've tried the drivers from all of the above vendors, and sure enough they work all with the USR2410. If your card has the same FCC ID, it's the same card on the inside. The Netgear MA401 has FCC ID PD5LMWP100 and it's also identical on the inside to the WL11000. The Netgear version is made by Delta Networks, Inc. My theory is that these cards are all based on a reference design from Intersil.
By far the best utility set for this card comes with the bundle from Teletronics. They also have a card with part number WL11000 which turns out to be compatible. Throw away your USR drivers and use the Teletronics WL11000 driver and utility instead. The Teletronics utility has tons of goodies like an AP scan function (a poor man's Netstumbler for Prism cards), ping, MAC address setting, link test, site survey, etc. Highly recommended! Here is what the site survey tool looks like:
It's great for finding the best channel to use at a particular location. If you don't know how to install non-default drivers in Windows, I have posted detailed instructions in this thread at the Netstumbler website. Alternatively, you can use the driver/utility set from Sitecom for their WL-002 card. This software appears to be identical to the stuff from Teletronics.
For Windows CE/PocketPC, USR seems to be the only game in town. Their drivers work ok on the Netgear MA401 as well, and i'll bet they work w/ most of the cards listed above. You can scan the CE registry using a registry editor after installing the driver and see TONS of compatible cards listed.
I used an exacto knife to crack the covers open, but the covers didn't want to slide out of the main case. After fiddling a while I had to just bend them outwards and leave them attached. Here is a top view of what's inside:
Not too interesting from the top. The gold traces on the outside edges are the antennae. The bottom view is much more interesting:
Now we can see that the 5 holes are pads for attaching an antenna jack. The outer 5 holes are obviously ground, and the inner hole is to feed the signal to the antenna jack. Some extra SMT parts needed to make the required connections. Below is a zoomed view of what's within the red rectangle:
The pads within the red circles are unpopulated. Unfortunately, the Eumitcom schematics submitted to the FCC were mangled and missing the critical portion containing the antenna connections. Fortunately, though, the Delta Networks schematic contains the info we need. If you zoom in on the top left, you see 2 150pF caps labeled NO POP: C37 and C141 which lead to a BNC jack. These are the parts we need to solder into the empty pads in the red circles. The Netgear MA401 also comes in a model with an external antenna. From Page 3 of the internal photos, we can see that they removed L4, C28, and L15. These parts are circled in blue below:
So now we have all the pieces to the puzzle of how to add the antenna jack:
Remove the parts circled in blue.
Add 2 150pF caps where the red circles are located.
Solder in a SMA PCB mount jack (BNC is too lossy @ 2.4GHz).
Our friends at guerrilla.net have a detailed procedure for adding a jack to an SMC-2632 (identical card to ours). The only place it differs is that they don't bother to remove C28 and L15, so one internal antenna is still connected. Pretty laborious procedure, but very nice results.
Update 2002-11-13: The guerrilla.net site is still down. I've mirrored their SMC-2632 Antenna Mod pages for your convenience. They have photos of a very nice looking way to mount the jack.