Introduction

On my various web pages I've talked about connecting your Palm device with an external modem or cell phone using your Palm Hotsync cradle, which works great.  However, carrying around and using your Hotsync cradle isn't very convenient.  An alternative to using a Hotsync cradle, is to use either a Hotsync cable or Modem Cable supplied by Palm Computing.  Palm Modem cables are very hard to come by since Palm no longer manufactures them.  If you have an older Palm device or Palm III derivative, you can buy a Palm Hotsync cable at most PDA stores for about $18.00 US and use it in conjunction with a null modem adapter to connect with a modem/cell phone.  The only way to currently get a Palm V cable, however, is to buy the Palm V travel kit (which contains a Palm V hotsync cable, battery charger, etc.) for a price of $50.00 US!  Instead of paying big bucks I decided to make my own Palm V modem cable which is described below.

To make a Palm modem cable, you essentially need two connectors, some wire, and a soldering iron.  To determine the wiring schematic for the cable, I used my existing Palm V Hotsync cradle and null modem adapter to "tone out" the pins and determine the proper connectivity.  The most difficult task in making a Palm V cable, is finding a Palm V serial connector (the connector which attaches to the bottom of the Palm V).  This is a proprietary connector which cannot be bought off-the-shelf as a standard electronic part.  I did a little searching on the net and found a vendor who was willing to sell me the Palm V connector:
 

Pacific NeoTek

Contact: Tawnia Forster (tawnia@pacificneotek.com)

They sold me a Palm V connector for $8.50 each, plus shipping.
Shipping within the US is $4.20; outside the US is $6.

When you receive the connector from Pacific NeoTek, it should look like Figure 1.

You will also need another connector for the other end of the cable to connect with your modem.  Since I wanted to use this homemade modem cable with my Zoom Pocket modem (and cell phone) I chose a male DB-9 connector.  I purchased this connector at Fry's Electronics for 89 cents.

The last piece of hardware was the cabling.  Fortunately, I had an old hotsync cradle from my PalmPilot Pro, so I used the cable from the cradle for my new modem cable.  You could certainly use any cable which had 5 independent wires bundled inside.

Wire soldering

The next step is to solder the wires on both ends of the cable to their appropriate pin connections.  Figure 2 shows the two connectors and the necessary wiring configuration.

Carefully use a soldering iron with slight amounts of solder to make the necessary connections.  Unfortunately, the Palm V connector does not have a strain relief, so you must improvise to prevent the soldered wires from being ripped from the connector if the cable is pulled too hard during operation. I decided to spread silicon sealer into the cavity of the Palm V connector (after I was satisfied with my soldering job) and press the two halves of the connector together.  After a day, the silicon sealer hardened to a point where it sufficiently acted as a adhesive and mild strain relief for the cable.  Likewise, I did the same thing for the DB9 connector in it's backshell.  Figure 3 show the completed cable.

I can now use my new cable with my Palm V to connect with my Zoom Pocket modem, or with the Touchpoint cable on my cell phone.  I can also use this new cable as a Hotsync cable if I use an additional null modem adapter.

 
Alternative... buy one!

If you don't want to mess with building a custom cable, you can check out www.syncablesolutions.com and just buy one from them.  I've never bought from them, but I haven't read any complaints on the Palm newsgroups.