AMERITRON AL-82 Gebruiksaanwijzing - 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-82. The maximum drive that the AL-82 will tolerate is

approximately 130 watts. At this drive level the output of the AL-82 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

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

reading on the 2000 RF Watts scale.

Adjust the ALC ADJ control on the rear panel until the amplifier

output is no more than the desired maximum power obtained in

step 1.

The exciter internal ALC will maintain linearity. The amplifier

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.

20oio

higher than normal.

WARNING!!

ALC will prevent over-power operation.

SSB PROCEDURE

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

PROCEDURE'".

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.

SSTV, FM, RTTY, PACKET, AMTOR:

The plate current should be limited to 600 mA maximum. The grid

current should be limited to 250 mA. Tune the amplifier for peak output

power with the drive reduced to the grid and plate current below the

ratings given.

NOTE:

Some t;xciters 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 efficiency with reduced drive. Poor linearity, splatter or

even damage to components may result from failure to follow these

instructions. Exclusive grid current usually indicates that the loading

control is set too far counter-clockwise for the amount of drive being

applied to the amplifier or that something in the antenna system has

changed impedance (arcing) during operation.