Nautel NX50, Operation And Maintenance Manual, Page: 10 / 166

NX50 Operations and Maintenance Manual Description
Page 1-2 Issue 3.3 2016-02-08
Ac-Dc Power Stage
See electrical schematic
SD-1
. The ac/dc power supply stage contains the input power transformer
that receives the main ac input to the transmitter. It also contains the transmitter’s low voltage power
supplies and rack interface PWB. The ac/dc power supply stage also include a three-phase SCR
rectifier assembly, Hall Effect current sensor, and B+ distribution assemblies.
The secondary of the power transformer is applied to the SCR rectifier assembly to create the
transmitter’s B+ voltage. The output of the rectifier assembly is fed through the Hall Effect current
sensor, which supplies a dc current signal to the rack interface PWB. The rectifier assembly output is
applied to the B+ distribution assemblies, which then provide the B+ voltage to the RF power
modules, and a B+ sample to the rack interface PWB.
One phase of the power transformer’s secondary is also used to provide a source for the low voltage
dc power supplies and an ac sample for the rack interface PWB. The low voltage power supply
outputs (+48 V, +15 V and +12 V) are distributed throughout the transmitter via the rack interface
PWB.
Ac Power Transformer
The NX50’s power transformer can be set to use a range of input voltages. See Section 4,
“Connecting transformer taps/load wiring” on page 4-1 in the NX50 Installation Manual .