Specifications

RF Driver section includes three basic stages of amplification.
This is to provide enough RF drive for the 160 Big Step and
Binary RF Amplifiers. The section normally operates below its
capacity, and is capable of providing the additional RF drive
when required.
The RF Driver section is contained in the Right PA compart-
ment. The components that make up the section are located in
the top half and in the rear of this compartment behind inter-
locked doors.
See VIEWS 10 & 15 for a more exact location of the compo-
nents.
NOTE - The following sections describe the RF signal flow in
general, for more detail refer to the Buffer Amplifier, Predriver,
and RF Drivers in Section C, Driver Combiner Motherboard.
Refer to Figure 4-5, RF Driver Section for the following discus-
sion.
4.5.1.1 Buffer Amplifier
The plug in Buffer Amplifier amplifies the RF Interface output
from a TTL level to approximately 20 Vp-p. There are two
separate amplifiers on the Buffer Amplifier board, Buffer A and
Buffer B, which are driven in parallel. Buffer A output drives
Predriver A, while Buffer B output drives Predriver B. Buffer A
and Buffer B are both active at the same time. However, only
one of the Buffers is in the RF chain at any one time. The use of
Buffer A or Buffer B is selected by the Predriver A/Predriver B
control on the Driver Encoder board.
4.5.1.2 Predriver RF Amplifier
The Predriver amplifies the Buffer signal to a level adequate to
drive the 14 Driver RF Amplifiers via the Predriver Tuning
board. There are two Predrivers, Predriver A and Predriver B,
which are constantly being driven by their respective Buffer
Amplifier output. Only one of the Predrivers is active at any one
time. Predriver A or Predriver B is selected on the Driver
Encoder board.
The Predriver RF Amplifier, the 14 Driver RF Amplifiers and
the 160 Big Step and Binary RF Amplifiers are fully inter-
changeable.
4.5.1.3 Predriver Tuning
The input of the Predriver Tuning board is driven by the Pre-
driver Amplifier. The selected Predriver RF output passes
through a series-tuned inductive/capacitive network and the
primary windings of the transformer on the Predriver Splitter.
The value of inductance and capacitance is frequency deter-
mined. This board also controls the Predriver voltage by relay
contacts across dropping resistor R1.
4.5.1.4 Predriver Splitter A46 and Driver Drive Cables
The secondary of the PredriverSplitter dividesthe RF signal and
drives the 14 Driver RF Amplifiers, D1-D14. There are 4 con-
nectors on the outside of the splitter to which the Driver Drive
Cables connect. The other end of these cables connect to the
Driver Combiner Motherboard.
Figure 4-5. RF Driver Section
12/16/03 888-2339-002 4-9
WARNING: Disconnect primary power prior to servicing.