NV30/NV40 Operations and Maintenance Manual Description
Issue 3.3 2014-12-10 Page 1-7
10 kW combiner/filters
Each 10 kW combiner/filter (A16, A31, A49 and A64) is a 2-stage combiner that accepts the RF
outputs from four RF power modules and provides a single RF output. Each 10 kW combiner/filter
uses three 3 dB hybrid couplers - two of which are used in the initial pair of 5 kW combiners, which
each accept the outputs of two RF power modules. The equal amplitude, 90° out-of-phase
(quadrature) RF signals are combined at the 3 dB hybrid coupler outputs and applied to a third and
final, 10 kW 3 dB hybrid coupler. Again, the equal amplitude, quadrature RF signals are combined.
The combined output is applied to a 10 kW low pass filter before being applied to a 20 kW combiner.
Any amplitude or phase imbalances between 3 dB hybrid coupler inputs cause a proportional signal
to be applied to the applicable reject load assemblies. The amplitude of the 5 kW Rej Ld Pwr signals
(via J5 and J6) represents imbalance between the combined outputs of the first stage of combining.
The amplitude of the 10 kW Rej Ld Pwr signal (via J7) represents imbalance between the combined
outputs of the second stage of combining (differences in pairs of RF power modules).
20 kW combiners
The 20 kW combiners (A30 and A63), which are hybrid couplers, accept the RF outputs from the
10 kW combiner/filters. The equal amplitude, 90° out-of-phase (quadrature) RF signals are combined
at hybrid coupler outputs and applied to the 40 kW combiner.
Any amplitude and phase imbalances between the inputs of the 20 kW combiners causes a
proportional signal to be applied (via J1) to the applicable reject load assemblies. The amplitude of
the 20 kW Rej Ld Pwr signals represents imbalance between the combiner inputs.
40 kW combiner
The 40 kW combiner (A48), which is a hybrid coupler, accepts the RF outputs from the 20 kW
combiners. The equal amplitude, 90° out-of-phase (quadrature) RF signals are combined at the hybrid
coupler output and applied to the output power probe.
Any amplitude and phase imbalances between the inputs of the 40 kW combiner causes a
proportional signal to be applied (via J1) to the applicable reject load assembly. The amplitude of the
40 kW Rej Ld Pwr signal represents imbalance between the combiner inputs.
Output power probe
See Figure SD-8. The output power probe (A13) monitors the transmitter's forward and reflected
power and generates the Fwd Pwr Sample (A1J1) and Refld Pwr Sample (A2J1) signals applied to the
control/monitor stage for protection and monitoring. RF monitor PWB A3 provides a nominal 4.5 V
(NV40) or 3.7 (NV30) rms [at 40 kW (NV40) or 30 kW (NV30) signal at A3J1 for use with a
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