DE
DANIELS
ELECTRONICS
2-2
VT-3H040 VHF Enhanced Transmitter Instruction Manual
2.2
Frequency Selection
The operating frequency is determined by the synthesizer channel number selected. The relation
between channel number and operating frequency is, in general, specific to the family and model
of transmitter. In the case of both the VT-3H035 and VT-3H045 transmitter models, each
channel corresponds to either a 5 kHz or 6.25 kHz increment in frequency, depending on whether
the channel number is below 5000 or above 4999 respectively; beginning at a base frequency of
29.0 MHz. This relationship is summarized by the following formulas:
For channel numbers 0000 to 4999
CHNL#=
Tx
frequency
−
29 MHz
5.0 kHz
or
Tx
frequency
= CHNL#
kHz
[
] +
MHz
5
x
29
For channel numbers 5000 to 9999
CHNL#=
Tx
frequency
−
29 MHz
6.25 kHz
+ 5000
or
Tx
frequency
= (CHNL# - 5000)
kHz
[
] +
MHz
6.25
x
29
Alternatively, a frequency and channel lookup table is available in the 'Channel Designation
Table' manual for the VT-3H040.
A channel can be selected from a set of 15 (maximum possible) factory programmed channels by
the four channel select lines available at the rear 'F' connector on the Transmitter Main Board. A
single user selectable channel is set by switches located on the Transmitter Main Board. See the
Transmitter Main Board Manual for details.
2.3
Transmitter Assembly and Adjustment
All modules are mounted on the Transmitter Main Board which then forms a single assembly.
An enclosure is formed by an extruded aluminum shell that slides over the Transmitter Main
Board as illustrated in section 3.2). This shell also serves as a heatsink 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