AMX TXC16 Plus Specifications download pdf (Page 138)

SG-2000 MANUAL 131

The SGC Building, 13737 S.E. 26th St. Bellevue, WA. 98005 USA

21.10 Serial Logic Switches (Schematic J30100500)

These serially loaded switches are contained in IC3 and IC4 on the LPA. The

microprocessor sends a serial 16 bit word out along the data line while CS4 is

held low. The 16 bit word is then latched into the two ICs and reflected on the

output as either an open or closed collector. These high or low impedances

control all the relays, High / Low power setting, high temperature protection

circuitry, and the receive and transmit control voltages. The control voltages are

used in determining the direction of IF frequencies and filters on the exciter and

to enable RF power output.

21.11 Tone Generator (Schematic J30100920)

The tone generator is a PLL used strictly as a programmable divider. The PLL

takes the reference frequency 11.94 MHz and divides it down to a frequency that

can be used to produce an audio tone. Since there is a divide-by-4 circuit after

the PLL, the microprocessor assembly must take this into account. For example:

for a desired tone of 1000 Hz, the microprocessor programs the PLL with the

following result; 11940000/4/1000=2985

This would also mean that any deviation by the reference oscillator will be

reflected in the tone by a 4000 to 1 ratio. For a 3 Hz deviation on the reference

clock, there would only be a .0075 Hz deviation on the tone output.

21.12 Oven SwitchOn the back of the unit is a switch labelled BAT-SW. If

there is power to the radio, this switch is used to select whether the power to the

oven unit is supplied continuously (BAT) or only comes on when the SG-2000

itself is turned on (SW). Selecting either option depends on the operator’s

situation. Selecting BAT will keep the oven at the proper temperature even

when the radio is off and enable immediate transmission upon turning on the

radio; however, it will put a very small drain on your power source. Selecting the

SW position will eliminate this drain but you will need to let the SG-2000 warm

up for 10 minutes after turning it on before you can transmit. SGC recommends

that if you are operating a fixed station on AC power, use the BAT position; if

you are operating a mobile or marine station powered by a battery and go long

periods between using the radio, select the SW position.

21.13 Alarm Generator

The alarm generator is for emergency use only and is activated by pressing two

keys on the front panel. It generates two tones at 1300 and 2200 Hz using the

tone generator mentioned above. The individual tone durations are intervals of

250 mS, and alternate for 45 seconds. The 250 mS time intervals are measured

internally by the microprocessor clock. The 45 second alarm time is generated by

a calender clock used in keeping track of the date and present time.

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AMX TXC16 Plus Specifications Page 138