Vertex Standard VXA-150 Reference manual

VXA-150
Alignment
Vertex Standard Co., Ltd.
1
Introduction
IntroductionIntroduction
Introduction
The VXA-150 is carefully aligned at the factory for the specified performance across
the Aircraft and Weather bands. Realignment should therefore not be necessary except
in the event of a component failure.
The following procedures cover the adjustments that are not normally required once
the transceiver has left the factory. However, if damage occurs and some parts
subsequently are replaced, realignment may be required. If a sudden problem occurs
during normal operation, it is likely due to component failure; realignment should not
be done until after the faulty component has been replaced.
We recommend that servicing be performed only by authorized Vertex Standard
service technicians who are experienced with the circuitry and fully equipped for
repair and alignment. If a fault is suspected, contact the dealer from whom the
transceiver was purchased for instructions regarding repair. Under no circumstances
should any alignment be attempted unless the normal function and operation of the
transceiver are clearly understood, the cause of the malfunction has been clearly
pinpointed and any faulty components replaced, and realignment determined to be
absolutely necessary. Problems caused by unauthorized attempts at realignment are
not covered by the warranty policy
Vertex Standard reserves the right to change circuits and alignment procedures, in the
interest of improved performance, without notifying owners.
The following test equipment (and familiarity with its use) is necessary for complete
realignment. While most steps do not require all of the equipment listed, the
interactions of some adjustments may require that more complex adjustments be
performed afterwards. Do not attempt to perform only a signal step unless it is clearly
isolated electrically from all other steps. Have all test equipment ready before
beginning, and follow all of the steps in a section in the order presented.
Correction of problems caused by misalignment resulting from use of improper test
equipment is not covered under the warranty policy.
Note: Signal levels in dB refereed to in this procedure are based on 0 dBµ = 0.5 µV
(closed circuit).

VXA-150
Alignment
Vertex Standard Co., Ltd.
2
Required Test Equipment
Required Test EquipmentRequired Test Equipment
Required Test Equipment
RRadio Tester with calibrated output level at 200 MHz
RIn-line Wattmeter with 5% accuracy at 200 MHz
R50-Ω, 10-W RF Dummy Load
RRegulated DC Power Supply adjustable from 3 to 15 VDC, 2A
RFrequency Counter: ±0.2 ppm accuracy at 200 MHz
RAF Signal Generator
RAC Voltmeter
RDC Voltmeter: high impedance
RVHF Sampling Coupler
Alignment Preparation & Precautions
Alignment Preparation & PrecautionsAlignment Preparation & Precautions
Alignment Preparation & Precautions
A 50-ΩRF load and in-line wattmeter must be connected to the main antenna jack in
all procedures that call for transmission, except where specified otherwise. Correct
alignment is not possible with an antenna. After completing one step, read the next
step to see if the same test equipment is required. If not, remove the test equipment
(except dummy load and wattmeter, if connected) before proceeding.
Correct alignment requires that the ambient temperature be the same as that of the
transceiver and test equipment, and that this temperature be held constant between
20~30 °C (68-86 °F). When the transceiver is brought into the shop from hot or cold air,
it should be allowed some time to come to room temperature before alignment.
Whenever possible, alignments should be made with oscillator shields and circuit
boards firmly affixed in place. Also, the test equipment must be thoroughly warmed up
before beginning.
Set up the test equipment as shown below for transceiver alignment, apply 7.2 VDC
power to the transceiver. Refer to the drawings for Alignment Points.
PLL Reference Frequency
PLL Reference FrequencyPLL Reference Frequency
PLL Reference Frequency
RConnect the wattmeter, dummy load and frequency counter connected to the
antenna jack, and tune the transceiver to 120.000 MHz.
RTransmit, and adjust TC1001 on the RF Unit, if necessary, so the counter
frequency is 120.000 MHz (±100 Hz).

VXA-150
Alignment
Vertex Standard Co., Ltd.
3
TX Power Adjustment
TX Power AdjustmentTX Power Adjustment
TX Power Adjustment
RConnect the wattmeter and dummy load to the antenna jack, and tune the
transceiver to 128.000 MHz.
RTransmit, and adjust VR1003 to obtain 1.5 W RF (carrier) power indicated on the
wattmeter (without audio modulation input).
TX
TXTX
TX Modulation Adjustment
Modulation AdjustmentModulation Adjustment
Modulation Adjustment
RConnect the Radio Tester to the antenna jack, then adjust the AF generator output
level for injection of 200 mV rms @ 1 kHz to the MIC jack. Leave the transceiver
tuned to 127.500 MHz.
RTransmit, and adjust VR1002 to obtain 85 % modulation (±3 %) as indicated on the
Radio Tester.
RReduce the AF generator output level to 20 mV rms, then adjust VR1001 to obtain
30 % modulation (±3 %) on the Radio Tester.
Internal System Alignment Routine
Internal System Alignment RoutineInternal System Alignment Routine
Internal System Alignment Routine
This feature uses a programmed routine in the transceiver which replaces many
previously-complex discrete component settings and adjustments with digitally-
controlled settings via the CHANNEL selector knob. Transceiver adjustments include:

Squelch Hysteresis Adjustment

Squelch Threshold Adjustment

Squelch “Tight” Adjustment
To begin, set the transceiver to 127.500 MHz, and turn the transceiver off. Then, press
and holding the LAMP switch, PTT switch and the CHANNEL selector knob while
turning the transceiver on.

Squelch Hysteresis Adjustment (HSSQ)
Press the CHANNEL selector knob, then select the squelch hysteresis level
using the CHANNEL selector knob.
Next, press the CHANNEL selector knob.
Rotate the CHANNEL selector knob to select the next setting.

Squelch Threshold Adjustment (THSQ)
Inject a –9 dBµ (0.35 µV) RF signal (with a standard modulation: 30 % AM
modulation @ 1 kHz), then press the CHANNEL selector knob
twice .
Now rotate the CHANNEL selector knob to select the next setting.

VXA-150
Alignment
Vertex Standard Co., Ltd.
4

Squelch “Tight” Adjustment (TISQ)
Increase the RF signal level to +15 dBµ (5.6 µV), then press the CHANNEL
selector knob
twice .
Press and hold the in the CHANNEL selector knob for 2 second to save all
setting and exit.
Resetting the CPU
Resetting the CPUResetting the CPU
Resetting the CPU
If you are unable to gain control of the transceiver (or if you want to clear all memories
and settings to their factory defaults), press and holding the MONITOR button and PTT
switch while turning the transceiver on.