Midland LXT314 Manual

LXT314
ALIGNMENT PROCEDURE
Page 1
1. REFERENCE TEST EQUIPMENT
A. HP8921A Cell site test set or HP8920A, B Communication Test Set with Spectrum
Analyzer option.
B. Fluke 187 Digital Voltmeter
C. HP E3615A Power supply
2. TEST POINT
A. ANTENNA : Test point is not prepared. Use antenna contact with
ANTENNA_GND_T(antenna ground).
B. VCO reference voltage : Test point 1 is prepared.
C. RX audio output : Test point SPKOUT is prepared or use ear-jack(3.5mm).
D. TX Mic. Input : Test point MICIN is prepared or use ear-jack(2.5mm) with 10uF
coupling capacitor.
E. Battery Vcc : Test point is not prepared. Please use mechanical contact.
F. Up Key : Test point UP is prepared.
G. Down Key : Test point DW is prepared.
H. Function Key : Test point Menu is prepared.
I. Monitor Key : Test point SCAN is prepared.
J. PTT Key : Test point PTT is prepared.
K. CALL Key : Test point CALL is prepared.
Note. : All key can be activated when connect with ground.
3. VCO ALIGNMENT
A. Set unit to Channel 1 and connect a voltmeter to TP1 (VCO PD).
B. Press & hold PTT.
C. Extend L303 until the voltmeter reads 2.0V.
D. Cover shield-plate on VCO can and monitor the voltage on TP1. The voltage should be
1.5Vdc +/-0.2Vdc. If the voltage is not 2.0Vdc +/-0.2Vdc, realign L303 until meet to
requirement.
E. Release PTT button so units is in receiving mode and monitor the voltage on TP1. The
voltage should be in the range 2.0Vds +/-0.5V
F. Set unit to channel 14.
6. Press & hold the PTT switch and observe the voltage on TP4. The voltage should be 2 –
3,5 Vdc.
7. Release PTT and observe the voltage on TP4. The voltage should read between 2.0 - 3.5
Vdc.
Note : VCO shield-can should be soldered after VCO alignment is finished.
4. TRANSMITTER FREQUENCY ALIGNMENT
A. Press & hold the PTT button.
B. Align CT201 trimmer capacitor such that the output frequency is equal to the channel
frequency with a maximum error of +/- 200 Hz. CT201 is located on the left side of
20.95MHz X-tal.

LXT314
ALIGNMENT PROCEDURE
Page 2
5. TRANSMITTER OUTPUT POWER CONFIRMATION
A. Set unit to channel 1 and power Hi mode.
B. Press & hold the PTT button.
C. Transmit power should normally be between 0.9W to 1.5W.
D. Set unit to channel 14.
E. Press & hold the PTT button. Ensure that Tx Power should be between 0.3-0.6W.
6. TRANSMITTER DEVIATION ALIGNMENT
A. Connect an audio generator (600 ohms) to the ear jack. The audio frequency should be set
at 1KHz with a level of 200mV RMS.
B. Connect an FM deviation meter (communications test set) to Antenna contact. Set the
monitor to read peak to peak divided by two [(pk-pk)/2] deviation. Set filter of equipment
from 25Hz to 15KHz.
C. Press & hold the PTT button.
D. Align RV2 for +/- 2.2 kHz deviation (+/-0.1KHz). RV2 is located on the bottom of the VCO
shield can.
E. Decrease audio generator level until deviation reads +/- 1.5 kHz (approximately 4mV) and
record generator level. Level should be between 2 mV and 5 mV.
F. Confirm that transmit audio distortion is less than 5%.
7. RECEIVER ALIGNMENT
A. Set the output level of the RF signal generator for -47dBm. The generator should be set for
1.5 kHz deviation at 1 kHz audio.
B. Set volume level 4 (It is initial.).
C. Connect Audio analyzer to SPKOUT.
D. Set equipment filter 25Hz to 15KHz.
E. Confirm that Rx Sensitivity is less than –120dBm (nominally –123dBm) by reducing the
output level of the RF signal generator until a 12 dB SINAD reading is achieved.
F. Set SSG output level until 9dB sinad sensitivity and align RV1 until the unit is un-squelched.
G. Set signal generator level to –47dBm.
H. With 1.5KHz deviation at 1KHz modulation, set volume for maximum audio. Audio level
should be on over than 1.9Vrms.
8. BATTERY INDICATOR CONFIRMATION
A. Set unit to receiving mode. Don’t set transmitter mode..
B. Set power supply voltage to 6V.
C. Decrease power supply voltage until low battery icon blinks.
9. POWER OFF CURRENT CONSUMPTION
A. Set power supply voltage to 6V and connect to unit.
B. Confirm current. It must be less than 100uA.
10. FREQUENCIES TABLE

LXT314
ALIGNMENT PROCEDURE
Page 3
Channel Freq. MHz Channel Freq. MHz
1 462.5625 12 467.6625
2 462.5875 13 467.6875
3 462.6125 14 467.7125
4 462.6375 15 462.5500
5 462.6625 16 462.5750
6 462.6875 17 462.6000
7 462.7125 18 462.6250
8 467.5625 19 462.6500
9 467.5875 20 462.6750
10 467.6125 21 462.7000
11 467.6375 22 462.7250

LXT314
LABORATORY TESTING PROCEDURES
Page 1
UNIT TEST - (UNIT ASSEMBLED)
TEST PREPARATION
1) Install 4 “AA” alkaline batteries (observe polarity markings).
zLeft bottom terminal is the system plus polarity
zRight upper terminal is the system minus polarity.
2) Press the power button.
SYSTEM TEST
1) Radiated Transmit and Receive performance may be observed.
2) Audio out & Audio in are available at the Headset jack.
LABORATORY TEST - (UNIT UN-ASSEMBLED)
TEST PREPARATION
1) Disassemble unit (4 screws – 3 behind batteries). Remove the PCB from the
cabinet.
2) Remove the antenna and install a 50 ohm coax cable in its place.
3) Either clip alligator leads or solder test leads to the power supply connections. The
positive terminal is the lower left PCB mounting hole. The negative terminal is the
lower right PCB mounting hole top of the 20.95MHz X-tal. (battery side view)
4) Connect 6VDC power source to the terminals, observing correct polarity.
5) Connect an 8-ohm load through the Headset jack (3.5mm mono-phone plug).
6) Connect a audio generator with 10uF coupling capacitor through the Headset jack
( 2.5mm mono-phone plug).
7) Select desired channel 1- 22 using CH up/down keypad switch. The rubber keypad
may be removed from the front cabinet and used directly on the PCB.

LXT314
LABORATORY TESTING PROCEDURES
Page 2
SPECIFIC TEST METHODS AND GUIDANCE
Modulation Characteristics – (paragraph 2.1047(a) of the Rules)
FOR TX AUDIO FILTER RESPONSE
1. Connect audio generator with 10uF coupling capacitor to microphone input jack.
Press PTT button.
2. Connect RF output with modulation meter. (Filters of modulation meter should be
set to a 50Hz to 15KHz.)
3. Adjust audio generator about 5-6mVrms for 0.75KHz modulation.
4. While transmitting, sweep generator and note measurement.
5. Please compensate the back-ground noise level.
Modulation Characteristics – (paragraph 2.1047(b) of the Rules
FOR TX AUDIO LOW PASS FILTER RESPONSE.
1. Connect audio generator with 10uF coupling capacitor to microphone input jack.
Press PTT button.
2. Connect AC voltmeter or other test equipment via jumper wire to TP-9.
3. Adjust audio generator for 200mV.
4. While transmitting, sweep generator and note measurement.
Occupied Bandwidth – (paragraph 2.1049(c) of the Rules)
1. Connect an audio frequency sweep generator with 10uF coupling capacitor to
microphone input jack.
2. Adjust audio generator to a frequency of 2500Hz and a level of 100mV rms (+16dB
above 10-12mV per FCC).
3. With a spectrum analyzer, transmit the radio and monitor the transmitter though an
antenna.
4. Note required measuements per FCC.