User's Manual

Digital UHF Transmitter Chapter 4, Circuit Descriptions
DT835A, Rev. 1 4-28
six outputs of the splitter are used,
depending on output power, (A1 thru
A6) UHF Amplifier Trays (1281-1100),
the number used depending on the
output power needed, (A7) a 4, 5 or 6
Way Combiner, depending on the
output power needed, (A8) an Output
Coupler (1016-1043), (A10) an AC
Distribution Assembly (1278-1200) for
Single Phase AC Input or (1278-1100)
for Three Phase AC Input and (A11) an
Interface Panel. If the Amplifier Array
contains the 2.5 kW or 3 kW Output
Power Kit, the Array also has (A12) a
Reject Load Assembly (1278-1312).
In the 2 kW configuration no Reject
Load Assembly is needed.
The output of the (A4) Variable
Phase/Gain Tray, located in the Exciter
Assembly, connects to (A2) the Side A
Amplifier Assembly (1278-1300). The
output of the (A5) Variable Phase/Gain
Tray connects to (A3) the Side B
Amplifier Assembly (1278-1300). The
RF Input from the Variable Phase/Gain
Tray connects to the RF Input Jack J1
on (A11) the Interface Panel located in
the Amplifier Array Assembly. The RF
is cabled to the COM Input of (A9-A1)
the 8 Way Splitter which splits it eight
ways maximum. Four to Six of the RF
outputs of the Splitter, depending on
the output power needed, are
connected to J1, the RF Input Jack on
each of the up to six UHF Amplifier
Trays (1281-1100). The outputs of the
Splitter that are not used are
terminated with 50O. Each of the UHF
Amplifier Trays amplify the RF signals
to the power needed to produce a total
of 4000 - 6000 Watts Peak of Sync
after combining of the two Amplifier
Assemblies, with a maximum of 600
Watts Peak of Sync output per Tray.
The outputs of the UHF Amplifier Trays
are combined in (A7) the 4, 5 or 6 Way
Combiner that provides half of the
power needed to generate the output
power of the Transmitter. In Amplifier
Arrays which contain a 2.5 kW or 3.0
kW Amplifier Array Power Level Kit, the
Reject Outputs of the Combiner are
connected to (A12-A2) the Combiner
Reject. Load Board (1278-1311) in
(A12) the Reject Load Assembly (1278-
1312). In the 2 kW Amplifier Array
Power Level, the Combiner has a
different Reject Load Assembly. The RF
Output of the Combiner is cabled to
(A8) the Output Coupler Assembly
(1016-1043). The Output Coupler
Assembly supplies a Forward and a
Reflected Power Sample of the output
from the Amplifier Assembly which
connects through the SMA Connectors
J2 and J3 located on the Interface
Panel to the Metering Panel located in
the UHF Exciter Assembly.
In each UHF Amplifier Tray, a Forward
Power Sample and a Reflected Power
Sample, from the 4 Way Combiner
Board, are connected to the Dual Peak
Detector Board, Single Supply which
provides peak detected forward
samples to the Amplifier Control Board
that supplies the samples to the front
panel meter of the UHF Amplifier Tray
and also to the Interface Panel for
remote monitoring. Before exiting each
UHF Amplifier Tray the RF is fed
through a Circulator which protects the
Tray from high VSWR conditions. The
Reject Port of the Circulator provides a
Reject Sample to the 4 Way Combiner
Board which supplies the Reflected
Sample to the Dual Peak Detector
Board, Single Supply located in the UHF
Amplifier Tray that connects to the
front panel meter. The outputs of the
(A2 & A3) Amplifier Array Assemblies
connect to (A4) a Hybrid Combiner
(55223A) which combines the outputs
into a single output.
The two Enable (Operate) Commands
from the UHF Exciter Tray, located in
the UHF Exciter Assembly, connect to
the Terminal Block (A9-TB2) mounted
in each Amplifier Array. The terminal
block splits the Enables in each array
and supplies them to all of the UHF
Amplifier Trays. The Enable is needed
to turn on the Switching Power Supply
located in each UHF Amplifier Tray. If