1024 TRANSMIT SWEEP GENERATOR

TM 11-5820-918-13

1-8. The transmitter consists of three modular units mounted in an environmentally

protective case. The units are the 1024 transmit sweep generator (unit 1), the 5018

power amplifier (unit 2), and the 4011 filter/diplexer (unit 3).

1-9. 1024 TRANSMIT SWEEP GENERATOR. This unit controls and generates the

TCS-4B sweep-frequency signal. The sweep signal originates from a precision quartz

oscillator frequency standard. From this source, a linearly upward frequency ramp

is developed by means of decade counters which program a frequency synthesizer.

The synthesizer uses a phase-locked loop technique to control a variable-frequency

oscillator whose output is locked to the internal frequency standard. Since both

transmitter and receiver use identical sweep generator circuits based on identical

frequency standards, only synchronization of sweep start times is required to ensure

reception of the sweeping signal. The necessary synchronization is performed at

the beginning of operations and is fully explained in the receiver manual TM 11-5820-

917-13. Once synchronization is accomplished, the transmitter and receiver clocks

are essentially linked in time. To safeguard this link, a standby battery power sup-

ply is included in the transmit sweep generator unit. The standby battery supply

is automatically switched on in the event of primary AC line failure and provides

power for the frequency standard, timing circuit, and frequency blanker memory.

A new battery supply will sustain timing and memory functions for approximately

24 hours. A front panel pushbutton switch initiates a test of the sweep generator,

checking power supply voltages, proper synthesizer lock, and suitable battery volt-

age.

1-10. 5018 POWER AMPLIFIER. The power amplifier receives approximately 1 mW

(0 dBm) of signal power from the transmit sweep generator and linearly amplifies

it to approximately 100 watts. The power amplifier uses four parallel transistor am-

plifiers whose outputs are combined to produce a near constant output

over the entire operational frequency band (2-30 MHz). A 32 MHz low pass filter

is incorporated into the power amplifier which effectively blocks all frequencies above

32 MHz. Other filtering circuits are included in the filter diplexer unit.

1-11. 4011 FILTER/DIPLEXER. This unit contains the circuits necessary to perform

sequential, half-octave, low-pass filtering of the TCS-4B signal as it progresses

through the frequency sweep. The low-pass filtering attenuates harmonics 60 dB

below the fundamental signal. In addition, the unit incorporates a 2.5 kW PEP (stand-

ard rating) diplexer, which, when selected, combines approximately 2 watts of TCS-

4B RF output with the communications transmitter output. The balance of the TCS-

4B power (98W) is absorbed in a 50 ohm dummy load mounted on the rear panel of

the 4011. Filtering of the sweep frequency is achieved by detection of the frequency

as the sweep progresses followed by sequential activation of each of eight half-octave

filters (2-2.8 MHz, 2.8-4.0 MHZ, etc.). The 4011 unit also contains circuits for mea-

suring the forward or reflected sweep frequency output power of the TCS-4B. The

measured power is displayed on a meter on the 1024 front panel.

1-12. EQUIPMENT SUPPLIED

1-13. As supplied, the TCS-4B transmitter includes the following items:

P/N 1024-1000 or P/N 1024-1100

Transmit Sweep Generator, Unit 1

P/N 5018-1000

Power Amplifier, Unit 2

P/N 4011-1000 or 4011-1120

Filter/Diplexer, Unit 3

1-3