AMERITRON AL-1200 Manuale di istruzioni - Pagina 11

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ALC (Automatic Level Control)

The primary use of the ALC is to reduce the input drive power

to a safe level for the AL-1200. The maximum drive of the AL-

1200 will tolerate is approximately 130 watts. At this drive level

the output of the AL-1200 may be in excess of 2000 watts when

properly tuned. The ALC should be connected and adjusted

after the amplifier is properly tuned on CW. Use a shielded

audio-type cable with a standard male phono connector to

connect the 0-20 volt negative ALC voltage to the exciter ALC

input. Consult the exciter manual for proper connection details.

Setting the ALC ADJ Control

Proper adjustment of the rear panel ALC control can be

achieved by the following steps:

1. Load the amplifier according to the tune-up instructions (with

the ALC disconnected from the exciter) to the desired

maximum power.

2. Connect the ALC line and rotate the ALC control fully

clockwise looking at the rear of the unit.

3. Set the MULTIMETER switch to the PO position or observe

an external PEP meter or oscilloscope.

4. Set the transmitter audio control about 20% higher than

normal

5. Speak in the microphone in a normal tone of voice and

observe the reading on the 2000 RF Watts scale.

The AL-1200 will operate with full output on all WARC bands except 24.5 MHz. The

AL-1200X (export model) will operate with full output on all WARC bands.

MAKE NO ATTEMPT TO PUT THIS AMPLIFIER IN SERVICE WITH THE COVER

REMOVED! CONTACT WITH VOLTAGES INSIDE THIS AMPLIFIER CAN BE

FATAL! ALWAYS DISCONNECT THE AMPLIFIER FROM THE POWER MAINS

AND WAIT FOR THE FILTER CAPACITORS TO DISCHARGE BEFORE

REMOVING THE COVER.

6. Adjust the ALC ADJ control on the rear panel until the

The exciter internal ALC will maintain linearity. The amplifier

ALC will prevent over-power operation.

SSB PROCEDURE

Tune the Exciter and Amplifier as described in "TUNE-UP CW

1. Place the SSB-CW switch in the SSB position.

2. Adjust the exciter gain control to permit voice peaks to reach

the same value the peak output meter read on CW when

fully loaded. The plate and grid currents should remain well

below 50% of the CW values during normal modulation.

NOTE: ,

Some exciters will put out short duration high power RF pulses

when first keyed. Exciter power output peaks may reach or

exceed full output level even if the exciter's power control has

been adjusted to deliver reduced power under "keydown"

conditions.

The amplifier loading control must be set high enough

(clockwise) to prevent extremely high energy levels from

developing in the plate and grid circuits of the amplifier. DO

NOT "UNDERLOAD" THE AMPLIFIER TO REDUCE

POWER. Never "retune" the amplifier to produce higher ef-

ficiency with reduced drive. Poor linearity, splatter or even

damage to components may result from failure to follow these

i t

STANDARD FREQUENCY COVERAGE

WARNING!!!

amplifier output is no more than the desired maximum

power obtained in step 1.