User Manual
17
CONTROL, LED, & CONNECTOR
FUNCTIONS
ACCESSORY Input Connector
Audio Input:
When Input 4 is switched to “HI” level, audio can be fed into pins 4 and 5 of the ACCESSORY connector on the
rear of the transmitter. Input level should be between 0.2 volts to 2.0 volts rms. The output impedance of the device
connected to Input 4 should be 8 - 600 ohms. For unbalanced operation ground pin 5 to pin 1, 8, 11, or 12 and connect
audio to pin 4. Use standard 15-pin “subminiature D” female connector with cover.
Transmit Control:
“TRANSMIT” control can be accomplished remotely by a switch circuit connected between pin 15 and one of the
available ground pins (pin 1, 8, 11, or 12).
External DC supply:
The SRPT-30/40A can be powered externally by either a 12-15 Volt DC supply or a 15-30 Volt supply. If powered
off a 12-15 Volt supply, connect three positive leads of the supply to pins 6, 7, and 14. Connect three negative leads of
the supply to three ground pins (pins 1, 11, and 12). Each of the three positive leads and each of the three negative leads
should be an 18 gauge wire. You may also use one 12 gauge wire for each positive and negative leads and split the
stranded ends into three at the connector end.
ATTENTION
FOR 12-15 VOLT EXTERNAL SUPPLY, THE OPTIMUM VOLTAGE IS FROM 13.5 TO 14.5 VOLTS.
APPLYING A VOLTAGE LOWER THAN 13.5, COULD LIMIT THE MAXIMUM RF OUTPUT POWER
AND/OR LIMIT THE OVERALL FREQUENCY RANGE.
ALSO, THE EXTERNAL BATTERY OR POWER SUPPLY MUST BE CAPABLE OF HANDLING A
CONSTANT 10 AMPS. THE VOLTAGE MUST REMAIN ABOVE 12 VOLTS AT ALL TIMES, EVEN
DURING INITIAL TURN-ON OF TRANSMITTER. POWER SUPPLIES TEND TO SURGE (DROP IN
VOLTAGE) WHEN THEY SEE AN INSTANTANEOUS LOAD INCREASE. ALSO, THERE WILL BE A
DROP IN VOLTAGE ACROSS THE POWER CABLES. THE POWER CABLES SHOULD BE AS
SHORT AS POSSIBLE AND AS HEAVY GAUGE AS POSSIBLE. IF THE VOLTAGE AT THE INPUT
OF THE TRANSMITTER DROPS BELOW 12 VOLTS, IN MANY CASES IT WILL CAUSE THE
SYNTHESIZER TO COME UNLOCKED.
ONE POSSIBLE REMEDY, IS TO TURN ON THE TRANSMITTER WITH THE FRONT PANEL
POWER ADJUST POT TURNED DOWN SO THAT THE OUTPUT POWER IS LOW. THEN SLOWLY
ADJUST THE POWER ADJUST POT TO DESIRED OUTPUT POWER.
If powered from a 15-30 Volt supply, connect three positive leads of the supply to three 15-30VDC pins (pins 2, 3,
and 10). Connect three negative leads of the supply to three ground pins (pins 1, 11, and 12). Each of the three positive
leads and each of the three negative leads should be an 18 gauge wire. You may also use one 12 gauge wire for each
positive and negative leads and split the stranded ends into three at the connector end.