Specifications

41D2355 4-WAY SPLITTER UHF
PUB13-01 Rev 0 Mar 4, 2013 12
6 AMPLIFIER BALANCE ALIGNMENT
After factory testing and installation in the transmitter, the 4-Way Splitter has minimal need for Amplifier Gain and
Phase Balance Alignment unless a new setup is being performed. It is, however, advisable to make this
measurement a part of the scheduled maintenance routine for the transmitter. The four amplifier blocks in the 4-
Way Splitter, named Amp 1 to Amp 4, are matched for gain and phase for specific channels. Any apparent
imbalance will be negligible unless a device failure has occurred in one of the amplifier sections.
The signal from the Modulator 1 is applied to RF Input 1 and signal from the Modulator 2 is applied to RF Input 2 if
second Modulator is used. These signals are applied to RF switch U3. When there is no signal applied to
TELEMETRY pin 8 “SELECT MODULATOR 2” RF Input 1 is connected to 4-Way RF splitter HY1,HY2 and HY3 and
RF Input 2 is terminated to the internal U3 resistor 50 ohm. When the +12VDC signal is applied to the
TELEMETRY-8 “SELECT MODULATOR 2” RF Input 2 is connected to 4-Way RF splitter and RF Input 1 is
terminated. Signal from U3 switch is applied to connector J20 and trough coaxial cable to 4-Way RF Splitter input
connector J21. Signal from J21 is split 2,3 or 4 ways depending of the application. Depending of the number of the
channels used splitter outputs are applied to amplifiers or are terminated if amplifier is not used for specific group
assembly.
First stage in the amplifier chain is PIN attenuator U106 MVA-2000+ which gain is controlled by potentiometer
R104. Phase shifter built around 3dB coupler HY101 1F1304-3 provides necessary phase shift matching transmitter
cube combiner requirements. Phase adjustment can be done by front panel potentiometer R129. Following phase
shifter is RF amplifier U101 12dB gain and 2 dB pi attenuater R106/R107/R108.
Front panel phase adjustments allow fine-tuning of the match between the cube amplifiers by setting the overall
phase of each amplifier. These adjustments are frequency sensitive so there is no need to perform them in field.
U102 provides 11dB gain and requires significant cooling.