Micro-Trak BFT Manual
This manual covers Version 1.0 of the Micro-Trak BFT tracking transmitter. The MT-BFT is a single channel, crystal-controlled APRS transmitter controlled by a standard Tiny-Trak 3 encoder PIC. For more complete information on the TT3 encoder and its associated configuration software, please download the TT3 manual and configuration program from the Byonics website. The MT-BFT is only available on the North American APRS frequency, 144.390 MHZ. The unit is sold fully assembled and tested. The MT-BFT requires as much as 9 Amperes of supply current to operate at full power. Do not exceed an operating voltage of 13.5 Volts.
Programming
Programming the MT-BFT is accomplished in the same manner as programming a Tiny-Trak3. The MT-BFT is connected to the serial port of a computer port running the Byonics TT3 configuration software via a serial cable and Null-modem adaptor. The adaptor is required to switch the serial receive and transmit connectors in respect to that of a GPS receiver, which we anticipate will be the normal operating mode for your transmitter. Like most Micro-Trak and TinyTrak products, the DB-9 connector on the PC board has a 5 volt output for powering a GPS. The DB-9 is plug and play compatible with the Byonics GPS 2 and many other 5 volt powered GPS receivers.
When transmitting, the MT-BFT creates an enormous radio frequency energy filed that can wreak havoc with your computer while you are attempting programming. There are two user adjustable trimmer potentiometers on the printed circuit board. The one marked “PWR” sets the bias for the amplifiers turn-on gate. It should be noted that all of the valuable adjustment of this trimmer is in the last few degrees of rotation, and power levels other than fully rotated are best carried out with an RF power meter while transmitting into a dummy load. During programming, turn the PWR control all the way Counter-Clockwise to minimize RF fields and prevent overwhelming your computer. ( You should connect the output to a dummy load or antenna any time you carry out any programming, operation, or testing !) With the power turned down, you may power the transmitter with a nine volt battery or other low current power supply. You must apply power to the unit to program the TT3 chip. Do not program the transmitter to send position reports more than once per minute, as it could cause the device to overheat.
Get pdf Micro-Trak BFT Manual
