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TinyTrak3 Adjustment
There are only a few adjustments required for proper operation of TinyTrak3. First, the transmit audio level should be
adjusted at R6 for proper deviation. Use the transmit tones buttons (1200 Hz/2200 Hz/Send Both) in the configuration
software to cause the TinyTrak3 to transmit while adjusting. You can listen on a separate receiver, and start the
potentiometer at maximum drive. Lower the drive level until there is a noticeable change in the receiver. Overdriving the
transmitter is a common cause of failure to decode. TinyTrak3 was designed for hand held radios. Some mobile radios
require more audio drive than TinyTrak3 puts out. If audio levels are too low, even with the R6 pot set to maximum,
consider replacing the 220K R5 with a 100K resistor or shorting jumper. This should allow for about double the audio
range.
The next adjustment point is R11, which is used to adjust the carrier detect base level. This should be adjusted such that
Carrier Detect LED is usually off, but turns on when the radio opens squelch. Radio receiver volume should be set to
maximum, and the radio can NOT have a constantly open squelch.
The last adjustment is the calibration value. This adjusts timing slightly to compensate for ceramic resonator error. Try a
few different values while monitoring the decoding on a TNC, and set to the value which gives the best decoding. Usually
the default 128 works best.
After setting the desired configuration options, TinyTrak3 should be connected to a radio, GPS, and power supply, and will
be ready for use. When power is applied, the carrier detect and valid LEDs should flash three times to show proper
firmware operation and proper LED wiring. If carrier is not detected, PTT LED D3 should light for about a second. Power
LED D4 should always be lit.
If a radio is connected, it should transmit periodically and a packet burst should be heard on a receiving radio. When the
receiver’s squelch is opened, the carrier detect LED should light, and all transmissions will be delayed. If a radio receiver
and TNC is available, packets should be able to be monitored.
