User's Manual

10 ALIGNMENT
Warning: Alignment must only be performed by qualified and trained service personnel.
The DTX module is aligned at the factory before shipment and should need no further adjustment. It is
possible that the gain settings for the audio input and output signal paths may need optimized. The
frequency trim, deviation, and balance should not need adjustment. The procedure for performing all of the
alignment steps is detailed below. The unit should not be opened for alignment; all adjustments are
electronic and effected through the programmer software.
10.1 REQUIRED TEST EQUIPMENT
Depending upon which alignment steps are to be performed, some or all of the following pieces of test
equipment may be required:
DC Power Supply - capable of operating at the correct voltage for the module and capable of 7 Ampere
minimum current.
RF Signal Generator- capable of operating at the carrier frequency of the module with an output level
adjustment and able to be frequency modulated.
FM Demodulator/Deviation Meter- capable of operating at the carrier frequency of the module.
RF Frequency Counter- must operate at the RF frequency of the unit with a resolution of 10 Hz or better
and an accuracy of +/-1 ppm (+/-150 Hz at VHF, +/-450 Hz at UHF) or better.
Audio Oscillator- must have sinewave output allow for output frequency and amplitude adjustment.
Oscilloscope
RF Power Attenuator or Dummy Load with coupled output- must be 50 ohms impedance at the operating
frequency and rated for the output power of the module and have an output which can drive the FM
demodulator at the correct level and the frequency counter.
RF Power Meter- capable of accurately indicating the RF output power of the module.
Note: Except for the power supply, a two-way radio test set may include most, if not all, of the required
equipment.
10.2 ALIGNMENT PROCEDURE
It is not absolutely necessary to perform all of the alignment steps detailed below. However, some
adjustments interact somewhat with others e.g. balance affects deviation, deviation affects AUX IN gain,
and the output power AUX IN gain has a slight affect on TX frequency trim. It may be prudent to spot
check all of the adjustments which interact. These will be indicated in the particular alignment step.
The programmer must be connected to the unit via the programming interface cable and the alignment
screen selected. During alignment, the channel may be selected via the channeling control lines on the
module or through the programmer. A channel pull-down menu allows for the selection. Also, the unit can
be keyed through the programmer, if desired. Note: Interrupting the power supply to the unit while the
programmer software is open will require exiting the software and re-opening it.
10.2.1 RX FREQUENCY TRIM
The RX Frequency Trim trims the unit on frequency during receive. This setting, if incorrect, may degrade
receive sensitivity, distortion, and possible recovered audio level, which in turn affects AUX OUT (RX)
Gain and Audio PA Gain. The receive frequency trim is not affected by any other alignment step.
To determine if the receiver is correctly trimmed to frequency, the 1
st
local oscillator frequency must be
measured. DO NOT KEY THE UNIT DURING THIS PROCEDURE AS SERIOUS DAMAGE TO
THE COUNTER MAY RESULT!