by: Dale DePriest - all rights reserved.
There is a new cable available for users needing to interface their PDA to a gps via the serial port. This cable is made by The SupplyNet and is custom made to provide an interface and optionally remote power to both units. I tested an advance copy of one that looks like the picture below. The released version is now available and looks just a little different.
This product features the ability to supply two different power outputs and the serial interface in the same cable. This cuts back significantly on the clutter of cables needed for an installation. In addition the power cable can be removed leaving you with an interface cable for use when taking a hike. They have cables for both Magellan and Garmin GPS units and a variety of PDA's including the Palm M125/M130/M500/M505/i705 and Palm Tungsten as well as PocketPC cables for Compaq iPAQ H3800/H3900, Dell Axim, and Toshiba E740/E335/E330.
The SupplyNet web site can be a bit intimidating to find things on when you first get there. The best thing to do is to go to the top of the page and select either Garmin or Magellan from the manufacturers list. This will get you a list of cables for your brand of unit and you can select the appropriate one from the list. Of course you could also go the opposite way and select your PDA manufacturer but that list is generally a lot longer since they make all kinds of cables for PDA's.
The one I tested was for a Garmin etrex/emap and an iPAQ 3970 PocketPC. This PDA is typical of the new breed of PDA's that require the use of rechargeable batteries and with a color screen they do not get exceptional battery life before needing to be recharged. This adapter provides the ability to do this recharging while the unit is still in use supplying a continuous moving map display in your car with suitable software and a GPS.
The power connector that plugs into the accessory socket in your car contains the voltage reducing regulator and produces about 5.2 to 5.3 volts output for the iPAQ. This voltage is plenty to keep it running in top shape. The variation I measured was caused by additional loads of expansion sleeves and the GPS itself. With the GPS running there is about 3.0 volts at the GPS connector. This is plenty of power and an emap could even use an external antenna without trouble. Power for the GPS in the production model is derived by adding a second regulator to the unit to drop the incoming votage to 3.3 volts (no load) for the etrex. There is an LED indicator on the connector to show that it has power. Since the main regulator is in the accessory connector you cannot cut this wire and attempt to hardware the cable to your car.
The power connector includes a round plastic disc at the end where it plugs into the car outlet. This can be unscrewed to reveal a fuse that can be replaced by the user if needed. Note this is spring loaded so be careful not to lose pieces when removing it. Be sure and match the 3A current value noted on the fuse. After you reassemble the unit depress then end a couple of times to ensure that it is seated properly against the spring.
I found the unit performed just as advertise. The etrex connector is a pfranc one and has the small round plastic locator on one side. This will need to be snapped off for use on an emap.
Most other models need to supply 12 Volts to the gps and only drop the voltage to the PDA. For this reason they will have the regulator built into the cable distribution box rather than the car accessory plug. A different power interface connector to the cable distribution box will be used to avoid the chance of plugging in the wrong power cable. For Garmin and Magellan these devices are listed on the web site. Note that there is no adapter for the Garmin G-38, G-40, or G-12 models since these need yet another voltage source and are now obsolete models. There are two models for Magellan units since there is a slight difference in the adapter connector used on these various models. Be sure and get the one that is for you model. Check the web site for a list.