POWER AMPLIFIER

TM 11-5820-918-13

play (1A5). It also compares the counted frequency with a memory containing the

center frequency of up to 16 bands that can be preset to blank the transmitter output.

A blanking signal from the memory inhibits the synthesizer output and suspends the

frequency counting by the filter set in the 4011 unit.

4-8. The sweep synthesizer assembly 1A1 generates a precision linear RF sweep signal

between 42 and 56 or 42 and 70 MHz. This signal is converted down by a synthesized

40 MHz signal to yield the 2-16 or 2-30 MHz sweep output. Operator selection of 2-30

MHz causes the sweep output to change by 1 Hz every 10 microseconds (a 100 kHz/see

rate). Selection of 2-16 MHz range cuts the sweep rate in half. Operator selection

of full power output causes the sweep synthesizer to output a one milliwatt (0 dBm)

signal level to the 5018 power amplifier. A 0.1 power selection cuts the synthesizer

output power to 0.1 milliwatt.

4-9. As shown in figure 4-1, the 1024 also contains a numeric display assembly 1A5

that provides a digital display of output frequency and internal system clock time.

A front panel power meter displays the measured forward or reverse power from a

power detector in the 4011 filter/diplexer unit. A complete power supply operates

the 1024 on 115 or 230 VAC input at 47-440 Hz. In the event of an AC line power

failure, a standby power supply provides battery-powered 5-volts DC to sustain

the programmer clock, the blanker frequency memory, and the 5 MHz frequency

standard. The subpanel control assembly 1A6 provides the necessary circuits to

operate the unit.

4-10. POWER AMPLIFIER. The 5018 power amplifier consists of two main assemblies

secured to two thick aluminum plates. The upper assembly (2A1, figure FO-1) con-

tains a low pass filter assembly (2A1A1) that attenuates spurious VHF signals on the

sweep generator signal and a power amplfier assembly (2A1A2) that divides the input

into two parts and amplifies each part to a maximum 10 watt level. One part is routed

to the 4011 unit for filter decoding. The other part is divided into four equal RF drive

signals. Each drive signal is amplified and then recombined into a maximum 100-watt

output to the 4011 unit. The second assembly (2A2, figure FO-1) contains the power

supplies that provide over 800 watts of regulated DC power to run the amplifier com-

ponents.

4-11. FILTER/DIPLEXER (figure FO-2). The 4011 filter/diplexer also uses two large

aluminum plates for assembly mounting. The upper section (assembly 3A1) contains

the filter set (3A1A1) that provides eight half-octave low-pass filters to suppress

harmonics of the power amplifier output to 60 dB below the fundamental. Selection of

the appropriate filter is done by a filter decode assembly (3A2A2) on the lower section

(assembly 3A2) that operates by counting the frequency of the 10 watt 5018 output.

If output blanking occurs, frequency counting is temporarily suspended. The

filtered sweep signal then passes through the power detector assembly (3A1A3) that

drives the front panel power meter on the 1024.

4-12. The 4011 implements either of two modes of operation: direct output of the

sweeping signal to the antenna or a diplexed output simultaneously containing approx-

imately 98 percent of a communications transmitter signal (up to 2.5 kW PEP) and 2

percent of the sweeping signal. A front panel DIRECT/DIPLEX switch activates the

relays that control these two modes. Selection of direct mode causes the two relays

in the 4011 to route the sweeping signal to the 4011 output. Selection of diplex mode

routes the sweeping signal to the diplexer assembly (3A1A2) where it is loosely coupled

to the antenna output. The 98 percent of the sweeping signal not coupled to the anten-

na output (along with about 2 percent of the communications transmitter power) is

4-2