Codan Radio Communications VT 4 150 User Manual

DANIELS

INSTRUCTION MANUAL

ELECTRONICS MT-3

RADIO

SYSTEMS

VHF AMPLIFIER

VT-3

132 - 174 MHz

Covers models:

VT-3/150 Amplifier

LTD.

®

Issue: 1 Previous Issue: N/A Issue Printing Part No.:

Ltd.

Date:

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May 98 Previous Issue May 98 IM21-VT3150AMP

Electronics

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Ltd.

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Reviewed By:

The

user's

authority

to op

erate

this

equipment

could be revoked through any

The design of this

equipment

is subject to change due to continuous

development. This

equipment

may

incorporate

minor changes in

detail

from the

Quality

Assurance:

_________________ Name Signature

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NOTE:

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modifications

contained

in this manual.

not expressly approved by

Daniels

Electronics

Ltd.

ii

VHF Amplifier Instruction Manual VT-3 132 - 174 MHz

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TABLE OF CONTENTS

Page

1 GENERAL....................................................................................... 1-1

1.1

1.2

Introduction Performance

............................................................................. 1-1

Specification

............................................................ 1-1

2

3

THEORY OF OPERATION

2.1

2.2 Power

2.3 RF

2.3.1

Amplifier

Requirements

Circuitry

VT-3/150

Operation

............................................................................ 2-2

2.4 Power Control

2.5 Power Sensing

2.5.1

2.5.2

2.5.3

Output

VSWR Sense .................................................................. 2-3

VSWR

................................................................... 2-1

.................................................................... 2-1

................................................................... 2-1

Lowpass

Circuitry

Filter

............................................................... 2-2

.............................................................. 2-3

Power Sense .......................................................... 2-3

Overload

.............................................................. 2-4

VT-3/150 AMPLIFIER ALIGNMENT

.................................................... 2-2

...................................................... 3-1

3.1 General.................................................................................. 3-1

3.2 Repair Note............................................................................. 3-1

3.3

3.4 Printed

3.5 Standard Factory Settings and Jumper

3.6

3.6.1

3.6.2

3.6.2.1

3.6.2.2

3.6.2.3

3.6.2.4

3.6.2.5

3.6.2.6

Recommended

Circuitboard

VT-3/150

Amplifier

General......................................................................... 3-2

VT-3/150

Test

Equipment

Numbering

Alignment

Amplifier

List ................................................. 3-1

Convention

....................................... 3-2

Configuration

............................. 3-2

....................................................... 3-2

Adjustment

............................................. 3-3

General Set-Up....................................................... 3-3

Output Output Antenna Antenna Procedure

Power

Alarm

(Forward Power) ........................... 3-4

Power......................................................... 3-5

VSWR VSWR

Alarm Overload

Verification

(Reverse Power).......................... 3-5

........................................... 3-6

............................................... 3-6

4

ILLUSTRATIONS AND SCHEMATIC DIAGRAMS

4.1

4.2

4.3

4.4

VT-3/150 VT-3/150 VT-3/150 VT-3/150

VHF

Amplifier

VHF

Amplifier VHF Lowpass VHF Lowpass

Component Schematic

Filter

Component

Filter

Schematic

Layout...................................... 4-2

Diagram

VHF Amplifier Instruction Manual VT-3 132 - 174 MHz

.................................... 4-1

...................................... 4-3

Layout............................... 4-5

Diagram

............................... 4-5

iii

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5 PARTS LISTS...................................................................................5-1

5.1

5.2

5.3

VT-3/150 VT-3/150 VT-3/150

Amplifier Low Pass Amplifier

Electrical

Filter

Parts List.............................................5-1

Electrical

Mechanical

Parts List .....................................5-3

Parts List ..........................................5-3

6

REVISION HISTORY

..........................................................................6-1

iv

VHF Amplifier Instruction Manual VT-3 132 - 174 MHz

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1

GENERAL

1.1 Introduction

The

VT-3/150

VHF

Transmitter

Amplifier

provides the final stage of RF

VT-3 132 - 174 MHz family. The 132 to 150 MHz, and 150 to 174 MHz with power. shielding, provides a good

The

VT-3/150

Amplifier

ground,

is housed in a

and also acts as a heatsink.

amplification

amplifier

continuously

machined

aluminum

and

has two

adjustable

case that ensures

filtering

distinct

for the

entire

frequency ranges:

2.0 to 8.0 Watts output optimum

RF

Additionally, which can be sensor protects the RF gain when a VSWR overload

Output

filtering The lowpass provided

Refer to Section 4 for the VT-3 132 - 174 MHz VHF layouts and

1.2

Type: MT-3 series VHF

Compatibility:

the

VT-3/150

individually

amplifier

Amplifier

configured as open

from high

condition

for the

filter

maximum

schematic

VT-3/150

Amplifier

assembly is mounted in a

attenuation

of

harmonic

diagrams

Performance Specification

is equipped with output power and VSWR sensing lines

antenna

collector

VSWR by

or

linear

outputs. The

approximately

internal

halving the amplifier's

is present.

is provided by the

separate

compartment

VT-3/150

of the

amplifier

Lowpass

case in order to

Filter

and other spurious signals.

MT-3 series

amplifier

Amplifier

Transmitter

and lowpass

module.

Main

Board.

filter

Frequency Range: 132 MHz to 150 MHz or 150 MHz to 174 MHz.

VSWR

Board.

component

RF Power

RF power Input:

Output:

adjustable

nominal

2.0 to 8.0 Watts

level

adjustable

held within +/- 2 dB of nominal.

Ouput

Input

Duty

Impedance

/Output

Isolation:

Cycle:

and

VSWR:

50 Ω, Type N

> 60 dB

100%: Continuous

connector;

Harmonic Emissions: Less than -80 dBc .

VHF Amplifier Instruction Manual VT-3 132 - 174 MHz

from +4 dBm to +10 dBm,

3:1 max. VSWR.

operation

from -40˚ C to

+60˚C.

1-1

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ELECTRONICS

2

Transmitter

Mismatch

Protection:

20:1 VSWR at all phase angles.

Transmitter

Operating

Transmit

Amplifier

Temperature

Humidity:

Voltage:

Current: 0.7 Amp

Standby Current: less than 0.5 mA.

Enable:

Enable

Alarm:

Forward power sense and reverse

- open

-

linear

Range: -30˚ C to +60˚ C,

95% RH (non-condensing) at +25˚ C.

+13.8 +9.5

Active

Response:

typically

within 5 msec;

VSWR; collector output

output

(separate

optional

(separate

lines only).

-40˚ C

or 'OR'ed

temperature

configuration);

test.

Vdc Nominal (range +11 to +16 Vdc),

Vdc Regulated.

typical

to

ground.

; 1.1 Amp

maximum

overdamped, rising to within 90% of full power

maximum (underdamped)

overshoot of

30%.

1-2

VHF Amplifier Instruction Manual VT-3 132 - 174 MHz

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1

2

Supply Current

THEORY OF OPERATION

2.1

A power control constant. The output power from the high power Vdc supply varies. Note that the frequency band does not change how the only changes a few

Power for the supply (if required) is always switched by the transmitter's PTT circuitry. The power from the input signal is present. The synthesizer or crystal control module controls the amplifier's synthesizer or crystal control module will ground the input

Amplifier Operation

circuit

VT-3/150

monitors the RF output power of

component

values in the RF circuitry.

Amplifier

continuously

+13.8

circuitry;

Vdc supply

switching it on by grounding the amplifier's input

amplifier

is provided from the MT-3

connected

until

to the

amplifier;

the amplifier's

+9.5

amplifier

will change as the

Transmitter

whereas, the

VT-3/150

U4 and keeps the power

amplifier

Board. The

+9.5

Amplifier

unregulated

Vdc supply is

will not use any

+13.8

operates;

+13.8

Vdc line is switched on and an RF

+9.5

Vdc to the

enable

line only when the RF signal

line. The

Vdc

from the synthesizer or crystal control module is phase locked. This prevents unwanted spurious emissions during

1) the

2)

transmitter

+9.5

Vdc is switched on by the PTT

start-up. A

is keyed on

typical

(+13.8

start-up sequence is shown below:

Vdc is always present)

circuitry

and the synthesizer

or crystal control module PTT line is pulled low

3) an RF signal is output to the

4) the

5) the

ampli

fier's

amplifier

input

enable

outputs RF power

amplifier

line is

activated

it

2.2

Typical Table and the current drawn from the

Table 2-1

Power Requirements

current

requirements

for the

VT-3/150

2-3 below. The current drawn from the

+13.8

Vdc supply should never

VT-3/150 Amplifier Current Consumption

Output

+9.5

Amplifier

+9.5

Vdc supply should never

Vdc

Power

2.0 W 0.64 A 0.51 A

4.0 W 0.79 A 0.75 A

6.0 W 0.89 A 0.93 A

8.0 W 1.04 A 1.10 A

Note: Current consumption measured at 153 MHz

VHF Amplifier Instruction Manual VT-3 132 - 174 MHz

at

different

+13.8

power levels are given in the

exceed

1.5 Amps.

Vdc

1.2 Amps

2-1

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ELECTRONICS

2

2.3 RF Circuitry

The RF module TL4), and the module connector. The frequency band of the range of the RF sample forward and reverse circuits mentioned

2.3.1

The approximately

circuitry

(U4),

U4.

consists of several blocks: a 7 dB input pad (R1, R2, and R3), an RF

an output power boosting transistor (Q7), three

VT-3/150

The output of U4 is further

amplifier

Lowpass Filter. The heart of the

module

power.

amplified

VT-3/150

U4. Directional

The sampled power is used by the sensing and power control

by Q1 to a

Amplifier

to control the amplifier's operation. The final step in the RF path is output

earlier, this is done by the

VT-3/150

Lowpass Filter.

VT-3/150 Lowpass Filter

VT-3/150

Lowpass

Filter

is a 50 ohm, 9 pole,

185 MHz. The lowpass

filter

reciprocal

assembly

well as any other out-of-band emissions so that a connector.

2.4

Power Control Circuitry

amplifier

directional

VT-3/150

maximum

is

determined

couplers (TL1, TL3, and

Amplifier

of 8.0 Watts at the

by the

is RF

operating

amplifier

antenna

frequency

couplers (TL1, TL3, and TL4) are used to

filter

attenuates

'clean'

filtering

with a 3 dB cutoff frequency of

the desired

signal's

harmonics as

RF signal is output to the

and, as

antenna

The

VT-3/150 RF power to control the gain of RF to the output power U4's

gain control pin. The output power

Amplifier

setpoint

employs a closed loop power control which uses a sample of the forward

and

generates

amplifier

U4. Op-amp

U1b compares the sampled RF an error signal which Q3 uses to control the setpoint

is

determined

by R7, the

Output

Power

voltage

Adjust

on

potentiometer.

The forward power is sampled by TL1, D5, C14, R13, L6, R12, and C15. The power control circuitry fluctuate

keeps the output power of U4 constant.

with

variations

in the

+13.8

Vdc supply voltage.

Therefore

the amplifier's output power will

2-2

VHF Amplifier Instruction Manual VT-3 132 - 174 MHz

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ELECTRONICS

3

2.5

The

VT-3/150

Power Sensing Circuitry

individually output is antenna

active

VSWR) the open

proportional

Amplifier

configured as open

low, that is, when a fail

is equipped with output power and VSWR sensing lines which can be

collector

condition

collector

transistor is turned on. In

to the sensed output power or

or

linear

antenna

outputs. In open

is

detected

(not enough output power or too high

VSWR is output.

collector

linear

configuration, the

configuration, a

voltage

Both the however, the

Output

Power

Alarm

Power Alarm setpoint. This is because the Alarm

2.5.1

The output power sense power. op-amp potentiometer. not collector

In open alarm the

circuitry.

Output Power Sense

The sampled power is

U3b.

Op-amp

The

amplified

installed)

condition

setting

or

operation

collector

occurs. The

of R21 (the

compared

(JU1 not installed, JU2 installed).

configuration, Q3 (the open

circuitry

U3b's

by op-amp U1a which then drives transistors Q4 and Q3 for open

Output

setpoint

Output

Power

uses

rectified

amplification

voltage

is then output

adjustment

Power

Alarm

and the VSWR

Alarm

setpoint

are

individually

must always be adjusted before the VSWR

Alarm

directional

by diode D6 and

is

range for the output power

Adjust

setpoint

is used as a

reference

coupler TL2 to sample some of the forward

controlled

directly

collector

capacitor

by R21, the output power

in

linear

output transistor) is turned on when an

C20 and then

operation

alarm

can vary depending on

potentiometer).

adjustable;

Alarm

by the VSWR

amplified

alarm

by

adjust

(JU1 installed, JU2

2.5.2

The VSWR sense from the amplified Adjust installed, JU3 not then drives transistor Q5 for open In open alarm of R36 (the VSWR

VSWR Sense

antenna

terminal. The

by op-amp

potentiometer.

collector

condition

occurs. The

circuitr

installed)

U2b.

The

y uses

reflected

Op-amp

amplified

or

compared

directional

power is

U2b's

voltage

to the output power

collector

operation

coupler TL3 to sample some of the power

amplification

configuration, Q5 (the open

Alarm

adjustment

Adjust

potentiometer).

range for the VSWR

rectified

is then output

(JU4 not installed, JU3 installed).

collector

VHF Amplifier Instruction Manual VT-3 132 - 174 MHz

reflected

by diode D7 and

is

controlled

directly

alarm

setpoint

capacitor

C25 and then

by R36, the VSWR

in

linear

operation

by op-amp U3a which

Alarm

(JU4

output transistor) is turned on when an

Alarm

can depending on the

setting

2-3

Codan Radio Communications VT 4 150 User Manual

Specifications and Main Features

Frequently Asked Questions

User Manual

1.1 Introduction

requirements

2.3 RF Circuitry