Instruction manual

AL-800 Instruction Manual
24
increase on the grid current meter. The grid overload circuit can be reset by momentarily placing
the
"STBY-OPR"
switch in the
"STBY"
position.
Some exciters generate high-level RF pulses when first keyed. These short duration pulses may
greatly exceed the exciter's steady-state operating output power. Unexplained activation of the grid
overload circuit may indicate the existence of this exciter problem.
Never under-load the amplifier to reduce the output power. The amplifier
"LOAD"
control must
be set to a high enough position (clockwise) to prevent excessive voltage and arcing in the tank
circuit
or excessive grid current. Repeated tripping of the grid overload circuit probably indicates the
"LOAD"
control is set too low.
1. Set the AL-800 front panel switches as follows:
POWER to OFF
OPR-STBY to STBY
MULTIMETER to HV
2. Plug the ac line cord into the proper voltage outlet.
3. Place the main power switch in the
"ON"
position. The meter lamps should light and the
blower should start. Read the 3500 volt scale on the multimeter. It should indicate 2500 volts
nominal and no more than 2700 volts.
4. With the amplifier still on
"STBY"
, tune the exciter into a normal 50 ohm load according to
the manufacturer's instructions. Turn the exciter drive down after tuning.
5. Place the amplifier's
"BAND"
switch on the same band as the exciter. Set the
"PLATE"
control and the
"LOAD"
control as indicated below:
CW
Frequency Plate Load
1.810 3-1/2 6-1/4
3.600 1-3/4 0-1/2
7.050 5 1-3/4
10.125 5-1/2 2-1/2
14.050 8 6
18.125 8 5-1/2
21.050 9 6-1/2
24.900 8-1/2 6-1/2
28.050 9 7-1/2