TINY-2/MICRO-2 Technical Ref., 2. Ed 1989
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RADIO INTERFACING
This section describes how to connect the signal cable between the TINY-2/MICRO-2 and the ra-
dio. The interconnection should be planned so as to minimize pickup of stray audio and RF noise
by the lines. You should use shielded wire for all signal-carrying leads.
Read the remainder of this chapter carefully before starting to interface the packet controller to
the radio.
Connect the TINY-2/MICRO-2 and radio according to one of the following methods. Then turn on
the packet controller and computer and start the computer communications program. Connect the
radio to a dummy load and listen to the transmission with another nearby radio. Set the transmit
level by the procedure in the Adjustments Chapter.
You should use shielded wire for all signal-carrying leads. If you notice a significant hum level in
the monitored audio, take measures to remove it. If the transmitter has an adjustable microphone
gain control, try reducing the sensitivity of the transmitter microphone circuit and increasing the
signal level from the TINY-2/MICRO-2 to minimize hum or other noise problems.
Radio Connector (J2) Pin Definitions
Interfacing the TINY-2/MICRO-2 to a radio involves connecting the following signals at J2, the five
pin DIN connector.
Pin 1 - Audio output from the TINY-2/MICRO-2 to the transmitter.
Pin 2 - Ground for both audio and PTT.
Pin 3 - Push-to-talk to allow keying the transmitter.
Pin 4 - Receive audio from the receiver speaker or auxiliary jack to the TINY-2/MICRO-2.
Pin 5 - Optional Radio Squelch input for RF Carrier Detection.
Radio Connector Viewed from Rear of Packet Controller
Direct Connection to Microphone and Speaker
The packet controller was designed to allow hookup and testing to be done without any modifica-
tions to the radio or any signal level balancing devices in the cables. The direct interconnection
method is useful if you devote the radio exclusively to packet. If you share the radio between
packet and voice, you may want to use the external interface method below. The packet control-
ler's audio signals are fed directly into the microphone connector or similar auxiliary input of the
radio, and the TINY-2/MICRO-2 output is adjusted to give a proper modulation level. The receiver
audio is taken from an auxiliary audio output or Speaker jack and fed directly to the packet control-
ler.
