Specifications

Using a Model 26 Fire Station Dispatcher for System Backup
144 025-9581M
Model 6203 FFSK Receive Level
♦ Setting the Model 6203 receive level:
1. At the Model 6203 location, connect an oscilloscope to measure the receive audio
signal at TP-1 on the Model 6203 motherboard. The expected signal will be
approximately 1.0 Vp-p (0.35 Vrms).
2. On the Model 6203 motherboard, turn R107 fully clockwise and R135 fully
counterclockwise.
3. Turn R62 (FFSK IN) fully counterclockwise. Set R86 (VOX threshold) to the
middle of its range.
4. Call the Model 26 site and have the operator there initiate the FFSK Test signal
from the Model 26.
5. If the voltage measured at TP-1, while the test signal is being received, is less than
1.0 Vp-p (0.35 Vrms), turn R62 clockwise until it reaches 1.0 Vp-p.
6. If the voltage measured at TP-1, while the test signal is being received, is greater
than 1.0 Vp-p (0.35 Vrms), turn R107 counterclockwise until it is reduced to 1.0
Vp-p (0.35 Vrms).
7. When finished making adjustments, let the test signal time-out or stop the test.
Model 6203 FFSK Transmit Level
♦ Setting the Model 6203 transmit level:
1. At the Model 6203, connect the laptop (or PC) to the serial programming port of
the Model 6203. Hit the SPACE bar three times to open the Model 6203 Main
menu.
2. Enter an “8” to start the {8} FFSK LEVEL SET test tone sequence. The Model
6203 should key its radio and transmit for 30 seconds and then unkey. If you finish
making before 30 seconds is up, you can cancel the test by hitting any character
key on the computer keyboard. If you require more time, enter an “8” again.
3. While the FFSK test tone is being transmitted by the Model 6203, use the service
monitor to measure the deviation of its radio transmitter. Adjust the R108 pot
(FFSK OUT) on the motherboard of the Model 6203 for a deviation of 2.5 kHz
(assuming wide band operation and a full channel deviation of 5 kHz). If the signal
cannot be set low enough, move JP5 in the Model 6203 from position TEL to
RAD. If the signal cannot be set high enough, move JP5 from position TEL to
PWR.
4. When finished making adjustments, let the test signal time-out or stop the test.
Note If there is an external control on the radio transceiver that allows
people to alter the receive audio level going to the Model 6203, this
control must be locked in some way after the adjustments are
made. Changing the level of the receive audio presented to the
Model 6203 can compromise the decoding of FFSK data packets.