Copyright Donald W Thomas, K5ZRQ
2
1.0 INTRODUCTION:
In putting together this manual, I used what limited information I could compile. The new updated
schematic, drawings and PCB layout were drawn by B. Bolin and were verified against a LA-600.
The Siltronix Model LA-600 is designed for operation in the 26 to 30 megacycle range. Due to the
high efficiency of the “Single Band” design, it is an excellent amplifier for the Ten Meter Amateur Radio
Operator, or for other services outside the United States.
Figure 1-1 Front Panel
The LA-600 features a High/Low RF transmit output selection and a pre-amplifier which provides
approximately 6 db gain on received signals. The LA-600 is designed with the best of components
available to provide years of trouble free service. It is important, however, the Operating Instructions
should be followed. The RF drive requirements to the amplifier should not be exceeded. Once the
unit has been installed and tuned for proper operation, retuning of the amplifier should not be required.
Even though the rugged 8950’s should provide years of trouble free operation, the most severe
conditions for the tubes exist during the tune-up procedure where the possibility of Off-Resonance
condition allows relatively large amounts of current to be drawn through the tubes. Unnecessary tune-
ups will reduce the life of the 8950’s. Once the unit is properly tuned for operation, major
readjustments should rarely be necessary. Occasional minor touch-up of the “PLATE” tuning to verify
peak performance is recommended. Both “PLATE” and “LOAD” controls may require small
adjustment when changing antennas or switching to and from a dummy load.
Figure 1-2 Rear Panel
