DE
DANIELS
ELECTRONICS
2-6
UT-4B400 P25 Digital UHF Base Transmitter Instruction Manual
2.4
Secure Communications
The transmitter is capable of sending secure communications if a DES-OFB encryption module is
installed. To transmit a secure signal, the transmitter must be programmed with the correct
encryption key using a Motorola KVL keyloader in conjunction with a Daniels Keyloader Cable.
Consult the instructions for the Keyloader for details on loading a key. A loaded key may be
cleared by pulling first the CLEAR KEYS 1* then the CLEAR KEYS 2* inputs to ground about
500 ms apart. Alternately, the PAC-4 controller may be used to clear the keys from all modules in
a system with a single keypress.
2.5
Transmitter Assembly and Adjustment
All modules are mounted on the Transmitter Main Board that then forms a single assembly. An
extruded aluminum shell that slides over the Transmitter Main Board as illustrated in section 3.2)
forms an enclosure. This shell also serves as a heat sink to remove heat from the Amplifier module
and for this reason, it is important that the four screws that bond the shell to the amplifier module
(Screws B in Section (3-2)) be installed before prolonged operation of the transmitter. Moreover,
the surface of the Amplifier module that contacts the shell should be clean and free of foreign
material. The enclosure is completed by the installation of front and rear plates, which are fastened
to the Transmitter Main Board.
Transmitter alignment is performed on a module by module basis and detailed steps are provided in
the respective manuals. Alignment is simplified by using an SR-3 Sub rack, SM-3 System
Monitor, and RF extender cable to provide transmitter power and signal interconnection.
Alternatively, +9.5 Vdc and +13.8 Vdc, as well as any required test signals, may be applied
directly to the individual modules. Refer to the corresponding manuals for details.
2.5.1
Controller Board Alignment
A Controller Board Alignment is performed at the factory and should not be required under normal
circumstances. A large change in operating frequency, as discussed in the next section, or
replacement of RF or Controller Boards may require a complete realignment operation. The Radio
Programming Software and Programming Cable must be used to access these tuning modes. This
operation requires that the transmitter module and amplifier be separately aligned in the following
order.
Sequence
Module
Manual Reference
(1)
Transmitter Main Board
Section 2.3 of this manual,
(2)
Amplifier
Amplifier Manual
