3-PATH CONTROLLER 1A4 (S/N 400101 and on)

TM 11-5820-917-13

low which turns on the green test lamp by means of Q2 and U8. If the test tone is

detected outside the window (either before or after), U4 goes high and Q1 turns

on the red test lamp. The 2-millisecond pulse at U10-10 delays the start of the test

tone detection sequence to skip over spurious noise signals that are occasionally

produced by the spectrum analyzer at the very beginning of its scan. If the

receiver is not sweeping when the TEST switch is pressed, U8-12 is low, and

the receiver sensitivity test is bypassed so that only the power supplies are tested.

The results of the receiver sensitivity test and the power supply test are ANDed

at U8-6 such that both tests must pass (when receiver is sweeping) before the

green test light turns on.

4-24. 3-PATH CONTROLLER 1A4 (S/N 400101 and on). The 3-path controller

module consists of the 3-path programmer circuit 1A4A2 and the receiver control

circuit 1A4A1. Its function is to control the synchronized timing of the chirp

receiver relative to the transmitter for automatic time-programmed sounder

operation.

4-25. 3-PATH PROGRAMMER (figure 4-4 and FO-12) (S/N 400101 and on). This

circuit uses three 60-minute timers and associated five-minute interval decoders

to perform the auto program starts. The 100-kHz clocks for the three timers

are obtained from the receiver control circuit (1A4A1). The clock for timer 1 is

applied to U67-5 (figure FO-12/2), the first of five cascaded decade counters.

The output appearing on U52-7 is one pulse/second. U27 (divide by 10) is the

"seconds" counter. U26, programmed to divide by six, is the " 10's of seconds"

counter. U25 and U33 work similarly for the minutes and ten's of minutes. The

other two timers are identical to timer 1. The clock circuits are powered from

the +5VB supply generated by the swtiching regulator (1A6A3). This supply

has a battery backup so timing synchronization is maintained during primary

line power failures. The timers are controlled by run /reset latches, formed by

U45, U43 and U34 (figure FO-12/1). U47-10 provides a momentary reset pulse

to the minutes and 10's of minutes counters when the front panel RESET push-

button is pressed. Actuation of the ADV TIMER pushbutton increments the

minutes counter by the addition of an advance timer pulse from U47-6. U16

through U23 (figure FO-12/3) form four, four-pole triple throw switches that

switch the BCD outputs of timer 1, timer 2, and timer 3 to the LED display.

The "minutes" outputs of each timer are decoded by 5-minute interval decoders

U13, U8 and U9 (figure FO-12/4). These decoders trigger one shots U68 and

U7 at the beginning of each 5-minute segment of the hour of their respective

timer. When the start of a 5-minute segment is decoded, four-pole, double-throw

switches U 12 and U 10 route the BCD outputs of the appropriate timer to U1.

U1 converts the four line, BDC, 5-minute segment time code, to a 1 out of

12 code.

4-26. The 12-output lines of U1 (figure FO- 12/4) are connected to the common

terminals of 12, single-pole, 4-throw switches on the front panel. U 1 provides

a low-going pulse output for approximately 50 microseconds (the period of the

one shots U68 and U7) on the line corresponding to the start of the particular

decoded 5-minute segment. The front panel switches select which path is

initiated for each 5-minute segment of the hour: 0 = no sweep, 1 = Path 1, 2 =

Path 2, 3 = Path 3. The three possible path lines (on J5- 16, -2, -15 respective-

ly) are gated by U4 with their respective timer pulse to produce an auto start

pulse at U5-6. U2 latches the path code for the 5-minute segment for use by

other circuits in the receiver.

4-10