Service manual

3.2 Rear Panel

Figure 2-2 Rear Controls and Connections

1 AC Line Cord

2 FUSE Holder: Accepts Type 3AG 15 Amp fuse.

3 GRID TUNING: Tunes input grid circuit of the 8950 Driver tube.

4 GROUND: Ground Lug for attaching ground wire from the chassis of the unit to earth ground.

5. C30: Tunes output plate circuit of the 8950 Driver tube.

6 OUTPUT: Connects RF output of the amplifier to the antenna coax feed line.

7 L10 Access Hole: L10 is for tuning RF input to the Preamp circuit.

8 INPUT: Connects RF Drive from exciter to input of amplifier.

4.0 OPERATION:

1. Setting the “MODE” switch to the “STDBY” position (or the main “POWER” switch to “Off”) permits

the exciter (transceiver) to operate directly into the antenna. This also allows any adjustment to be

made to the exciter before operating the LA-600. Use this setting for checking drive power.

2. Initial tune-up should be accomplished with the exciter (transceiver) set at the middle range of the

frequencies to be operated. This allows operation over the entire range without re-tuning the

amplifier.

3. The tune-up procedure should initially be accomplished by applying the exciter driving power for

short periods of time, not longer than 30 seconds. Release the push-to-talk button on the

microphone for about 30 seconds between each adjustment. During the final fine adjustments of

the tuning controls the drive may be held on for longer periods, provided only minor adjustments

are made. This method of tune-up will prevent the tubes from overheating during adjustments.

Once the tune-up procedure has been completed, the cooling fan, plus the high quality

components, will provide normal operation indefinitely with only an occasional minor tune-up.