NV30/NV40 Operations and Maintenance Manual Description
Issue 3.3 2014-12-10 Page 1-5
RF drive splitter/changeover assembly
The RF drive splitter/changeover assembly (A5) controls the routing of the main and standby
exciters and provides the RF drive signals for the 16 RF power modules. The assembly is comprised
of the splitter/changeover PWB (A5A1), two 4-way RF drive splitter PWBs (A2 and A3), two
attenuator PWBs (A4 and A5) and eight 3 dB hybrid couplers (U1 through U8).
Exciter relay control
The RF drive outputs from exciters A and B are applied to the splitter/changeover PWB (A5A1) at
A5A1J1 and A5A1J2 respectively. The Exciter Relay Control input (A5A1J3-4) is a signal applied from
the control/monitor stage that controls relay A5A1K1.
• When exciter A is selected as the main RF drive source, the Exciter Relay Control input is open
circuit and relay A5A1K1 will be de-energized. Exciter A's output will be applied to 3 dB
hybrid coupler A5A1U1.
• When exciter B is selected as the main RF drive source, the Exciter Relay Control input is near
ground potential (0 V) and relay A5A1K1 will be energized. Exciter B's output will be
applied to 3 dB hybrid coupler A5A1U1.
Exciter drive splitter
The splitter/changeover PWB’s 3 dB hybrid coupler (A5A1U1) is connected as a splitter. The RF
drive source (A or B) selected by relay A5A1K1 is applied to A5A1U1’s input. The signal is split into
two equal amplitude signals that are 90° out-of-phase. These split signals are applied to 4-way RF
drive splitter PWBs A5A2 and A5A3.
4-way RF drive splitter
Each 4-way RF drive splitter PWB (A5A2 and A5A3) accepts an output from the exciter 3 dB hybrid
coupler and splits it into four equal amplitude signals, using three 3 dB couplers identical to A5A1U1.
The outputs of each 4-way RF drive splitter are applied to the final RF drive splitters.
Final RF drive splitters
3 dB hybrid couplers A5U1 through A5U8 (identical to A5A1U1) are connected as splitters. Each
coupler accepts an output of the 4-way RF drive splitters and splits the signal into two equal
amplitude signals that are 90° out-of-phase. These split signals are applied to attenuator PWB A5A4
and A5A5.
Attenuators
The attenuator PWBs (A5A4 and A5A5) accepts the outputs from the 4-way RF drive splitter PWBs
and attenuate each of the signals for application to the 16 RF power modules. Attenuation values are
set in order to balance the RF drive output levels.
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