This May Be The Ultimate Dongle For Ham Applications!
Serial<–>USB interfaces based on the FTDI chip set do not suffer from the numerous problematic driver issues that plague the Prolific chipset. There are numerous serial<–>USB devices based on the FTDI chipset, but the one pictured below, a “Gearmo FTDI2X” is exceptionally useful for ham applications.
You get two DB9 serial ports from a single USB connection. For APRS applications, this means one port for the TNC and one for the GPS receiver. The two serial-side cables are 1 meter (approx 39″) long, while the USB-side cable is about .4 meter (approx 17″) long.
The COM port number assigned to each DB9 “sticks” and remains the same no matter what USB port you plug the cable into. (Prolific-based devices randomly acquire a different COM every time you plug the device into a different USB port, or via a hub instead of directly.)
The “goiter” in the middle of the cable is made of a smoky translucent plastic that allows 3 LED indicators for TXD, RXD and POWER to show through. These indicators can be quite useful for determining if devices on the serial side(s) are actually putting out data.
The installer for the FTDI driver is a single downloadable .EXE that contains drivers for every flavor of Windows 32 or 64 bit from Win98 to Windows 8. The appropriate version is automatically extracted and installed when you run the same setup on any flavor of Windows. I have installed this device and it’s associated drivers on two Win7-64 machines and 5 WinXP machines of varying vintages. The longest time from starting SETUP.exe to plugging in a functioning device was about 20 seconds. And it worked on the FIRST TRY each time!
The FTDI driver produces a far more comprehensive screen of options when you drill down through the Device Manager “Port Settings, Advanced” dialog. Instead of the generic serial port dialog that only lets you set COM number and the size of the TX and RX buffers, you get a huge menu of options. One of these is being able to toggle “Serial Enumerator” ON or OFF.
Serial enumeration means Window “Plug-N-Pray” tries to look through the serial port to identify the device attached to the port. In the case of ports connected to live NMEA GPS devices spewing out data once a second, this always results in Windows falsely identifying the device as a “Microsoft Ballpoint Mouse”, an ancient clamp-on serial trackball for early laptops. The mouse cursor then goes insane skipping all over the screen and randomly clicking on things as it interprets the NMEA data stream as mouse movements.
The FTDI chipset is capable of operating at serial speeds in excess of 900K/second (!), and will operate with 5, 6,7 or 8 data bits/character. The 5-bit mode, which is not supported by most dongles, makes it usable for classic 5-bit/char Baudot RTTY operation.
This product is made by “Gearmo”. Their website is here:
Note that they offer a variety of FTDI-based dongles in versions with 1, 2 or 4 serial ports from one USB port. They sell through the website. I got mine for USD $10 less from this Amazon page:
A version with a single serial port on a short (less than 1 foot) pigtail is here:
Googling for “ftdi usb to serial” yields quite a few other dongles based on this superior chipset, which should have about the same capabilities.
Another (single port) Gearmo from Amazon