E F Johnson 2424310 Users Manual

As forward biasing current increases, the impedance decreases to a low level. Therefore, the RF
level of the signal applied to Q6 increases as the bias current from the power control circuit
increases.

5.2.2.2 PA RF DEVICE (Q6)

Impedance matching for Q6 is provided by several capacitors, inductors, and sections of
microstrip. Q6 is an N-channel enhancement mode lateral MOSFET. The bias voltage (which is
required for the device to turn on) is controlled by the transmit signal. It is applied to the gate and
controlled by the logic through shift register U1. Therefore, this device is turned off in the receive
mode which improves isolation. Several capacitors, inductors, and resistors isolate this supply
from RF. Likewise, the 13-volt RAW BAT supply applied to the drain is isolated by similar
components.

From the output of the variable attenuator, the signal is fed to Q6. Q6 operates as a single-ended
device. It produces an output power of up to 35 watts.

5.2.2.3 FORWARD POWER DETECTOR, ANTENNA SWITCH,
LOW-PASS FILTER

The power control circuit senses Q6 output power to control the power output. A directional
coupler senses the forward power signal. This signal is then rectified by CR8 and applied to the
power control circuit. This signal is a DC voltage that increases in proportion to the level of
forward power. Refer to Section 5.2.2.4 for more information on power control.

PIN diodes CR9, CR11, CR12, and CR15 form an antenna switch that switches the antenna to the
transmitter in the transmit mode and the receiver in the receive mode. As stated in Section

5.2.2.1, PIN diodes have very high impedance when in the off mode and very low impedance
when forward biased. Transistors Q7 and Q9 are on in the transmit mode and off in the receive
mode.

In the transmit mode all four diodes are forward biased. The transmit signal then has a low
impedance path through CR9 to the low-pass filter and is blocked from the receiver by a
grounded quarter-wave line formed by C64, L15, and C66. A grounded quarter-wave lines
presents very high impedance at the non-grounded end. PIN diodes CR11 and CR15 and a second
quarter-wave line formed by C76, C77, and L17 provide additional isolation.

In the receive mode, all four diodes are in the off mode. Therefore, the receive signal from the
antenna is blocked from the power amplifier by CR9 and has a low impedance path through L15,
C74, L17, and C67 to the receiver in the RF module.

From the antenna switch the RF signal is applied to a low-pass filter formed by L11-L13 and
several capacitors and sections of microstrip. This filter attenuates harmonic frequencies above
the transmit band that could cause adjacent channel interference. R53 dissipates static buildup in
the antenna.

5.2.2.4 POWER CONTROL

Introduction

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The power control circuit maintains a constant power output as changes occur in power amplifier
temperature and voltage. It does this by sensing forward power and then varying the drive to Q6
to maintain a constant output power. The drive to Q6 is controlled by varying the voltage applied
to the variable attenuator circuit described in Section 5.2.2.1. In addition, the current applied to
final amplifier Q6 is sensed, and if it becomes excessive, power is cut back to a low level.

The power output level is set in 127 steps by a Digital-to-Analog (D/A) converter formed by shift
register U1 and several resistors. This converter is controlled by the microcontroller to provide
the following functions:

• It allows the RF power output level to be adjusted using the PCTune™ software.

• It allows the microcontroller to cut back power if the power amplifier temperature sensed by

thermistor TR1 becomes excessive.

• It allows high and low power levels to be selected by the user or to be fixed by programming

using the PCConfigure™ software.

Forward Power Sense

The forward power signal from the directional coupler is applied to pin 2 of amplifier U2-A. This
is a DC signal that increases proportionally to forward power. The other input to U2-A on pin 3 is
a DC reference voltage from the D/A converter. This signal sets the power output of the
transmitter.

U2-A is a difference amplifier which amplifies the difference between the reference voltage on
pin 3 and the forward power signal on pin 2. The turn-on time of U2-A is controlled by the time
constant of C17 and R28, and negative AC feedback to prevent oscillation is also provided by
C17.

This circuit operates as follows: Assume the output power attempts to increase. The DC voltage
applied to U2-A, pin 2 then increases which causes the output voltage on pin 1 to decrease.
Transistors Q1 and Q2 then turn off slightly which decreases the supply voltage to the variable
attenuator circuit. The input power to Q6 then decreases. The Q10 output power then decreases to
maintain a constant power output. R26 and R24 limit the voltage gain of Q2 and Q1 to
approximately two volts.

Delayed PTT

Transistor Q3 is used to delay power output for a short time after the transmitter is keyed. This
allows the synthesizer and exciter to stabilize so that the transmitter does not transmit off
frequency. The signal which controls Q3 is from microcontroller on the logic board. In the
receive mode this output is low, so Q3 is off. Pin 2 of U2-A is then pulled high by the 8-volt
supply applied through R29 and CR1. This causes the output on pin 1 of U2-A to go low which
shuts off Q2 and Q1. Then when the transmitter is keyed, after a short delay Q3 then turns on and
diode CR1 is reverse-biased. Only the forward power signal is then applied to pin 2 of U2-A.

Over-Current Shutdown

Current to Q6 is monitored by sensing the voltage drop across R33. Pins 3 and 6 of U3 are
connected across this resistor. As current increases, the output voltage on U3 pin 8 increases. This
voltage is applied to Schmitt trigger U2-B. When the voltage on pin 6 rises above the reference
on pin 5, the output on pin 7 goes low. This lowers the voltage applied to U2-A, pin 3 which

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lowers the power control voltage to the variable attenuator. This results in lowering the power
output to approximately 25% of full power.

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SECTION 6 ALIGNMENT PROCEDURE

6.1 GENERAL

6.1.1 INTRODUCTION

The following alignment procedure should be performed if repairs are made that could affect the
factory alignment or if adjustments may have changed for some other reason. To verify radio
operation, the performance tests in Sections 6.5 and 6.6 can be run. To perform transceiver
alignment, the following are required:

• PC-compatible computer

• Remote Programming Interface (RPI), Part No. 023-5300-000.

• PCTune software, Part No. 023-9998-499.

All adjustments are set digitally using the computer. Therefore, there is no need to disassemble
the transceiver to access adjustment points. In addition, audio test signals are generated internally,
so an audio generator is not required. The required test equipment is shown in Figure 6-1.

6.1.2 TUNE SOFTWARE

General

The PCTune software is a Windows
are as follows:

® program. Minimum software and hardware requirements

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• Windows® 95/98/NT/2000 (3.1 cannot be used)

• Pentium® processor or equivalent

• 16 MB of RAM

• A hard disk drive with at least 3 MB of free space

• A CD-ROM drive

• An available serial port

Software Installation

Proceed as follows to install this software:

1. Close all applications that are currently running (other than Windows).

2. Insert the CD-ROM containing the PCTune software into the drive.

3. From the Windows taskbar, choose RUN and open SETUP.EXE on the drive being used.
Alternatively, use File Explorer and double click SETUP.EXE.

4. Follow the instructions on the screen. The program is automatically loaded on the hard drive
and startup shortcuts or groups are created.

Starting PCTune

Select Start in the taskbar, then Programs > PCTune > PCTune.

Exiting PCTune

Select File > Exit or click the button.

Online Help

Online help is not available.

6.1.3 PCTUNE VERSION REQUIRED

PCTune, Version 2.0.0 or later is required to tune the RF board. The version number can be
displayed by selecting the Help > About menu.

6.2 MAIN SCREEN

The main PCTune screen is shown in Figure 6-2. Information on the various parts of this screen
follows:

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Menu Bar - Used to select the menus described in Sections 6.3.1-6.3.5.

Tool Bar - These buttons are used to quickly select functions as follows:

- Displays the screen used to set serial port parameters (see Section 6.3.3).

- Selects the Partial Tune mode the same as the Transfer > Tune Partial menu (see Section

6.3.3) This mode allows manual selection of the desired Tune Category and then automatically
steps through the various settings for that adjustment.

- Selects the Edit Mode which allows parameters in the selected screen to be changed without

stepping through each adjustment.

- Reads and displays the current parameters programmed in the radio the same as the Radio >

Read Tune Parameters menu (see Section 6.3.3).

- Writes the current tune parameters to the radio the same as the Transfer > Write Tune
Parameters menu (see Section 6.3.3). This occurs automatically when a Partial Tune adjustment is
completed.

- Exits the current Tune Category without writing parameters to the radio.

Radio Information

When tuning parameters are read from a radio by clicking the
> Read Parameters menu, the following information is displayed in the top part of the screen:

Type - The Radio Series selected by the Radio menu (see Section 6.3.2). The correct series must

button or selecting the Transfer

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be selected for communication with the radio to occur.

Band - The radio frequency band of the radio displayed after information is read from radio. Do
not select the band using Tools > Set Band (Section 6.3.4) because this may make the radio
nonfunctional.

Software DSP - The first number is the version number of the radio firmware (Flash/operating
code), and the second number is the version number of the DSP software.

ESN - The Electronic Serial Number electronically stored in the radio.

Tuning Categories

These buttons select the tuning adjustment to be performed. Different functions are
displayed for the 51xx and 53xx. If the Partial tune mode is selected, these buttons select the
particular adjustment that is performed.

Mode/Tool Tip

Information on the bottom line of the screen indicates the current tune mode and information
on the selected button on other information.

6.3 MENU BAR DESCRIPTION

6.3.1 FILE MENU

Selecting File > Exit closes the PCTune program.

6.3.2 RADIO MENU

[Insert 4300 radio menu]

The Radio menu shown above selects the radio type. [Insert correct selections for 4300] The
correct radio type must be selected for communication with the radio to occur.

6.3.3 TRANSFER MENU

COM Ports - Displays the following screen which selects the serial port (1-12) and baud rate

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(9600/ 19200) used for communication with the radio. Select the computer port to which the test
cable is connected (see Section 6.4.1), and 19200 baud is normally selected. These parameters
default to the last selected condition the next time the program is started.

Read Tune Parameters - Selecting this function or clicking the
parameters currently programmed in the transceiver and displays them in the various screens.

NOTE: Values in the various screens are for reference only and adjustments should be done only
by using the Partial Tune function.

Write Tune Parameters - Selecting this function or clicking the
tune parameters to the radio. This occurs automatically when a Partial Tune adjustment is
completed.

Tune Complete – Not available. This function automatically steps through all the tests required
to tune the radio.

Tune Partial - Selecting this function or clicking the
This mode automatically steps through all the adjustments of the currently selected Tune
Category.

button selects the Partial Tune mode.

button reads the tune

button writes the current

6.3.4 TOOLS MENU

Reset Radio - Resets the radio control logic similar to cycling power. This can be used, for
example, to change the radio series or band or exit an adjustment before it is complete.

Set Band - Selects the operating band of the radio. All tuning values are reset to the factory
defaults.

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CAUTION: Do not select this function because it can make the radio non-functional.

Reset Passwords - Erases all password information contained in the radio. This function can be
used, for example, to allow reprogramming of passwords if they are lost. NOTE: Radio
personality information is not erased by this function.

Erase EEPROM

CAUTION: This function erases important radio programming information as described
below.

Complete

CAUTION: Do not select this function because the radio must be returned to the factory to
make it operational again.

Parms Only
NOTE: The radio must be reprogrammed after this function is selected.

Tx/Rx Tests - Selects a screen which is used to check digital (Project 25) receive and transmit
performance. Refer to Section 6.5 for more information.

Restore Rx Front End Parameters - Programs the radio with default receive front end tune
parameters. Other parameters remain unchanged.

-Erases all EEPROM information, including factory programmed parameters.

- Erases all personality information.

6.3.5 HELP MENU

Displays the version number of the PCTune software and other information.

6.4 TUNING PROCEDURE

6.4.1 CONNECTING TEST SETUP

1. With transceiver power turned off, connect the RPI to an unused serial port of the
computer using a suitable cable (see Section 4.1.3).

2. Connect the RPI to the microphone jack of the transceiver using programming cable, Part
No. 023-5300-005 (see Figure 6-1).

3. If the receiver squelch adjustment will be made, connect a SINAD meter to the Speaker
Audio Out jack on the RPI (see Figure 6-3). This is a low level fixed audio output, and a 2.6 mm
(3/32”) phone jack is used.

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Figure 6-3 RPI Front Panel

4. Connect a wattmeter and a suitable load to the antenna jack of the transceiver for the
transmitter tests. For the receiver tests, connect the signal generator to the antenna jack through a
6 dB or greater isolation pad.

6.4.2 STARTING AND CONFIGURING PCTUNE

1. Start the program as described in Section 6.1.2 and turn transceiver power on. Select
Transfer > COM Port and make sure that the correct serial port and the 19200 baud rate are
selected (see Section 6.3.3).

2. Select the Radio menu and make sure the correct radio series (43xx) is selected [What is

the correct menu selection?] (see Section 6.3.2).

3. Select Transfer > Partial Tune and click the button for the desired Test Category.

4. Follow the instructions displayed on the screen to complete the various adjustments
required for a particular setting. Then repeat for other applicable Test Categories.

6.5 DIGITAL PERFORMANCE TESTS

6.5.1 GENERAL

This section describes how to check the performance of the radio on digital Project 25
channels. The PCTune software includes a Tools > Tx/Rx Tests menu that displays the screen
used for these tests.

• To perform these tests, a Digital Communication Analyzer such as Motorola R2670 or

IFR 2975 is required.

• These tests follow the TIA-102-CAAA-A “Digital C4FM/CQPSK Transceiver

Measurement Methods” specification. Refer to that document for more information.

• A P25 conventional channel preprogrammed by the PCConfigure software is used for

testing. The PCTune software does not select a specific test channel. The test channel
must be programmed with the following options:

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NAC - 293 (hex)
TGID (Talk Group ID) -1
Frequency - Any frequency in radio operating band

6.5.2 RECEIVE TEST SETUP

1. Connect the test setup and start and configure the PCTune software as described in Section 6.4.

Select the Tools > Tx/Rx Tests menu to display the Tx/Rx Tests screen. Then in the Test Type
drop-down list select Receive to display the following screen.

2. Connect the Digital Communication Monitor to the antenna jack using a 6 dB or greater

isolation pad. Set the Monitor output for the “1011” test pattern.

6.5.3 RECEIVE SENSITIVITY TEST

1. A tone should be heard from the radio speaker if the analyzer is set properly. Select the
“Short” or “Long” test in the Test drop down list and the radio should mute.

2. Set the analyzer output level for 0.35 µV (–116 dBm) at the receiver antenna jack
Bit Error Rate (BER) should be 5% or less. (This is a ratio of the receive bit errors to the total
number of bits transmitted.)

3. Increase the analyzer output level to 1000 µV (–47 dBm). The BER rate should be less
than 0.01%. This is the BER Rate Floor.

. The

6.5.4 TRANSMITTER TESTS

1. If applicable select the Tools > Tx/Rx Tests menu to display the Tx/Rx Tests screen.
Then in the Test Type drop-down list select Transmit to display the following screen. Connect a
dummy load to the radio antenna jack. Monitor the transmit signal with the Digital
Communication Monitor.

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2. Select the Low Deviation test and set the analyzer as required to measure transmitter
deviation. This test generates continuous repetitions of bits 10100000. Deviation should be 848­1037 Hz.

3. Click the “PTT” button to transmit the tone. When finished, click that button again to
turn the transmitter off.

4. Select the “High Deviation” test which transmits a standard transmitter test pattern.
Deviation should be 2544-3111 Hz.

5. The “1011 Hz” test transmits a standard 1011 Hz tone similar to that used for the receiver
test. This tone can be used to check the operation of other radios.

6. The “Silence” test transmits a standard silence test pattern which produces no receive
audio output by the receiving radio. This tone can also be used to test other radios.

7. Select “Normal” to transmit a standard voice signal by speaking into the radio
microphone.

6.6 ANALOG PERFORMANCE TESTS

6.6.1 GENERAL

The PCTune software is not used for analog channel performance testing. Simply program
the desired channels using the PCConfigure software as described in Section 4. The RPI is still
required to monitor the audio output signal from the radio.

Depending on the application, 12.5 kHz and 25 kHz test channels may need to be
programmed. Also, test channels programmed with or without Call Guard

squelch control may be required.

®

(CTCSS/DCS)

6.6.2 RECEIVER PERFORMANCE TESTS

1. Connect a signal generator to the antenna jack using a 6 dB or greater pad. Set the output

for the channel frequency, modulated with 1 kHz at the following deviation:

12.5 kHz Channels - 1.5 kHz
25 kHz Channels - 3.0 kHz

2. Connect a SINAD meter to the receive audio jack of the RPI (see Figure 6-3) This is a

low level fixed audio output.

SINAD Sensitivity

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3. Set the signal generator output level for 1000 µV (–47 dBm) at the antenna jack.

4. Decrease the signal generator output to obtain 12 dB SINAD. The signal generator output

should be 0.35 µV (–116 dBm) or less for 25 kHz channels, or 0.50 µV (–113 dBm) or
less for 12.5 kHz channels.

Audio Power Output and Distortion

5. Connect a distortion meter across the speaker load. Return the generator output to 1000

µV. Distortion should be 3% or less.

Squelch Sensitivity

6. Increase the signal generator output from zero and note the SINAD when unsquelching

occurs. It should be approximately 8 dB.

6.6.3 TRANSMITTER PERFORMANCE TESTS

1. Connect a wattmeter and dummy load to the antenna jack. Monitor the transmit signal

with a communication monitor.

Transmit Frequency

2. Monitor the transmit frequency and at room temperature it should ±100 Hz. At other

temperatures [–22° to +140° F (–30° to +60° C)], it must be within 2.5 PPM. This also
checks the receive frequency.

Transmit Power

3. Transmit power should be in the following ranges. High and low levels can be preset

anywhere in this range by PCTune. The factory default for high power is the maximum
shown below, and low power is half that value.
Standard Models -10-50 Watts

Transmit Modulation

4. Monitor the transmit modulation with a modulation meter. Speak into the microphone

with a normal voice. Modulation should be approximately as follows with no
CTCSS/DCS signaling present:

12.5 kHz Channels - 1.4 kHz
25 kHz Channels - 3.4 kHz

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5. Select a channel programmed with Call Guard (CTCSS/DCS) signaling. Maximum total

Call Guard and voice modulation should be approximately as follows:

12.5 kHz Channels - 2.3 kHz
25 kHz Channels - 4.7 kHz

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SECTION 7 PARTS LIST

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