User's Manual

OSMAC Base User Manual
Page 42
Manu.01_0405
12.2.3 Telco Interface - Receive Mode
1. Generate an RF carrier on the receive frequency, 1 kHz tone, 60% FSD = 3 kHz / 1.5 kHz. RF
level 10 uV.
2. Connect the TELCO line to the RX audio by holding the 1 button down on power up to bring-up the
test mode, then enter the password and press 6 F1 and F2.
3. Adjust R69 (telco line level) for a level of –13 dBm on the line.
4. Disable the RX audio by pressing F2 twice more. Generate a DTMF tone from the by pressing 3
and then F4.
5. Verify that the line level is between -15 and -12 dBm. Then press the DOWN arrow to turn off the
DTMF.
12.2.4 Telco Interface - Transmit Mode
1. Set the service monitor to measure the transmitter's FM deviation.
2. Generate a 2500 Hz tone onto the TELCO line from an external test instrument with a power level
of > 5 dBm into 600 ohms.
3. Connect the TELCO to the transmitter by pressing F1, then press F2 twice to key the transmitter.
4. Adjust R52 clockwise for maximum gain, then adjust R41 (limiter) for 4.5 kHz / 2.25 kHz deviation.
5. Adjust the TELCO signal to a power level of -15 dBm.
6. Adjust R52 so that the deviation is at half scale (2.25 kHz / 1.125 kHz).
12.2.5 Paging Modulation
1. Turn the unit off.
2. Generate a 1200 baud paging test signal by holding the 1 button down upon power up, then
entering the password and pressing 6 1 2. Specify an ON time of 30000 mS and an OFF time of
0mS.
3. Adjust R34 for 5 kHz / 2.5 kHz (0 to peak) deviation.
4. Turn off the power to the unit.
12.2.6 Voice Modulation & CTCSS
1. Turn the unit back on.
2. Key the transmitter using the F3 key. Adjust R160 so the carrier is on frequency.
3. Adjust R60 (mic gain) for 3 kHz / 1.5 kHz deviation when speaking into the mic with a normal voice
level from a distance of about 1 foot away.
4. Enable a 100 Hz CTCSS encoder on the transmit frequency.
5. Key the transmitter with the F3 key. Adjust R32 for 500 Hz / 250 Hz deviation of the CTCSS tone.
6. Measure the transmitter's power level to verify that it is set to the desired level with the internal
jumpers.