Racal Instruments RA6790/GM User manual
RACAL
RA6790
INSTRUCTIONS'
1.
Turn
on
POWER
2.
Establish
LOCAL
control
via
LOCAUREMOTE
button
3.
INITIALIZATION:
(a)
Press
and
hold
LOCK
button,
then
AM
button
(on
left
keypad,)
releasing simultaneously;
(b)
Word
'REMOTE'
will
appear,
then
the
frequency
and
BFO
digits will rapidly
scan
through
their
ranges-accompa-
nied
by
various changing
sounds
and
tones;
changing
modes
and
levels
will
fonow
also;
(c)
If
the
sequence
stops
and
displays
a2digit
byte
num-
ber,
the
self-check
has
detected
an
error
condition.
EXTERNAL
SPEAKER
CONNECTIONS
The
LOUDSPEAKER
OUT
connections for
the
RACAL
RA6790
are
found
on
J3
(DB25F)
on
the
rear
panel.
Use
a
DB25P
with
the
connections
as
listed
below:
LOUDSPEAKER
OUT:
pin
18
SIGNAL
GND:
pin
6
CHASSIS
GND:
pins
7,
8,
& 9
TITLE
PACE
NR,
: 10f1
RACAL
RA6790
INSTRUCTIONS
gg~~~~TlVE
nla
STARTUP
I
INITIALIZATION
I
TUNING
VERSION:
with
EXT.
SPEAKER
CONNECTIONS
1.0
FILENAME, jSECTION:
RACAL.SKD
HR\LOGOS
E.
T.
TANTON
N4XY
~
c~
•
.,·,.,.,..
.
..c.
r'
i
l....,
o
TeCHNICAL MANUAL
FOR
RA6790/GM
HF
RECEIVER
'"
RCI84249
(R·2174)
(R-217;4A)
..
~
1IO'1'ICl!::
TIlis
dOClment
COQ~ins
proprietary
in.foJ:lllation
furnished
tor
operation
~"'Iupport
puJ:tlOses
only
and
not
tor
tllProcurement.
ill~
"reprocunment
and
manufacturing
tiqhU
are
expressly
reseJ:Ve<f":~?,ft9
such
use
mey
~
..
de
ot
this
document.
either
direcuy'"~J:":"-fndirectly.
vithOllt
the
ptior
vritten
con.ent
of
RaC~
CcIIIIIluni':Zltions
Inc.
SUPERCEDES
ALL
PREVIOUS
EDITIONS
This
document
contains
technical
intormation
pertaining
:0
tile
ba~ic
RA6790/GM
111"
R.eceiver
and
to
the
IIIOdUied RA6790/GM.
!11"
Receiver.
"resultinq
from
the
addition
of
an
1D:
level
"r@turn
~oftware
lDOdlfication.
That
in.forsation
perUininq
to
the
basic
RAfi790/GM
111"
a.c.iver
is
provided
In
Sections
I
throuqh
VII
of
this
docuaent
viler....
intorwation
pertaining
to
the
lIIOdifi"ed
1lA6790/Ql
!!l'
a.c.iver
ia
prOYided
by
difference
d.!U
in
Section
VIII
ot
this
dOCUlHnt.
Copyright
By
RACAL
COMMUNICATIONS,
INrORf'ORATE[)
5
Research
Plaer.'-:
ROCKVILLE,
MARVlMHl
20850
U.S.A.'
11
SEPTEMBER
198q
,
\
\
CHANGE
NOTICE
INSTRUCTIONS
THIS
NOTICE
IS
FOR
REFERENCE
ONLY:
ALL
CHANGE
PAGES
HAVE
BEEN
INCORPORATED
IN
TEXT
RCI84249
C2
ClWfGE
NO.
2
RACAL
COMMCRICATIONS
INC.
. lCJJC1tvILLE,
MD
10
OC'l'OBER
1983
(Previous
change
notice
.no. A82,
Issue
No.1,
June
1,
1982)
TECHNICAL.MANUAL
FOR
RA6790/GM
. .
HF
RECEIVER
ReI
84249
RCI84249
(RA6790/GM)
,
August
1982
edition
is
changed
as
follows:
1.
Remove
old
pages
and
insert
new
pages
as
indicated
below.
2.
New
or
changed
text/tabular
information
is
indicated
by
vertical
bar
in
the
margin
opposite
binding
edge
of
the
affected
page.
3.
New
or
changed
illustrations
are
indicated
by a
pointing
hand
adjacent
to
the
affected
area.
4.
New
or
changed
schematic
diagrams
are
indicated
by
highlighting
affected
area.
5.
Added
or
changed
pages
are
indicated
by
including
a
change
number
adjacent
to
the
page
number
of
affected
page.
Remove
Pages
Cover/Title
Page
6-5
through
6-8
6-13
through
6-16
6-41
through
6-46
6-47
through
6-52
6-57
through
6-58
7-5/7-6
7-35/7-36
through
7-43/7-44
7-45/7-46
through
7-49/7-50
Insert
Pages
Cover/Title
Page
6-5
through
6-8
6-13
through
6-16
6-41
through
6-46
6-47
through
6-52
6-57
through
6-58
7-5/7-6
7-35/7-36
through
7-37/7-38
7-45/7-46
through
7-49/7-50
File
this
sheet
in
front
of
the
publication
for
reference
purposes.
CHANGE
NOTICE
INSTRUCTIONS
THIS
NOTICE
IS
FOR
REFERENCE
ONLY:
ALL
CHANGE
PAGES
HAVE
BEEN
INCORPORATED
IN
TEXT
RCI84249
C3
CHANGE
NO.3
RACAL COMMUNICA
nONS
INC.
ROCKVll..LE,
MD
14 FEBRUARY 1984
TeCHNICAL
MANUAL
FOR
RA6790/GM
HF
RECEIVER
ACI84249
(R-2174)
RCI84-24-9
(RA6790/GM),
Change
2,
10
October
1983
edition
is
changed
as
follows:
1.
Remove
old
pages
and
insert
new pages
as
indicated
below.
2. New
or
changed
text/tabular
information
is
indicated
by
vertical
bar
in
the
margin
opposite
binding
edge
of
the
affected
page.
3. Added
or
changed
pages
are
indicated
by including a
change
number
adjacent
to
the
page
number
of
affected
page.
Remove
Pages
Cover
/Ti
tIe
Page
i
through
ii
3-17
through
3-18
3-23
through
3-24-
Insert
Pages
Cover
/Title
Page
i
through
ii
3-17
through
3-18.2
3-23
through
3-24.2
File
this
sheet
in
front
of
the
publication
for
reference
purposes.
CHANGE
NOTICE
INSTRUCTIONS
THIS
NOTICE
IS
FOR
REFERENCE
ONLY:
ALL
CHANGE
PAGES
HAVE
BEEN
INCORPORATED
IN
TEXT
RCI84249
Cf4.
RACAL COMMUNICAnONS INC.
CHANGE
NO.4
ROCI<vn.LE.;
MD
11
SEPTEMBER 1984
TECHNICAL MANUAL
FOR
RA6790/GM
HF
RECEIVER
RCI84249
tR·2174) .
RCI84249 (RA6790/GM),
Change
3,
14
February,
1984
edition
is
changed
as follows:
1. Rem9ve old
;:>ages
and
insert
new pages as
indicated
below.
~e""
or
changed
textltabular
information'
is
indicated
by
vertical
bar
in
the
margin
opposite
binding edge of
the
affected
page.
Added or
changed
pages
are
indicated
by
including a
change
number
adjacent
to
the
3. page number
of
affected
page.
4.
New
or
changed
illustrations
are
indicated
by
a
poiming
hand
adjacent
to
the
affected
area.
Remove
Pages
Cover
ITitle
Page
vi
6-64
through
6-65
Insert
Pages
Cove!"
ITitle
Page
vi
6-64
through
6-65
File
this
sheet
in
front
of
the
publication
for
reference
purposes.
ERRATA
SHEET
RA6790/GM
HF
RECEIVER TECHNICAL
!1ANUAL
Below
is
a
list
of
corrections
to
the
above
referenced
manual.
PAGE
1.
4-3,
4.2.1.2
4-5,
4.2.2.1
4-13
4.3.2.1
2.
4-27
4.3.6.2
3.
4-37
4.3.7.4
.:..
4-40
4.3.7.5
5.
4-41
4.3.7.5
CHA...'1GE
~IOT
Ie
E
~.:o.
A82
ISSUE
:W.
1
SECTION
IV
.
1
4
2
13
1 6
1
13
n 9
in
22
itS
14
REQUIRED
CH.A.'iGE
CIRCUIT DESCRIPTION
References
to
the
upper
limit
of
t~e
HF
band
should
Change:
Change:
Should
Change:
read
"29.999
:1Hz
"
not
"30
:1Hz".
,
to
read
"to
U2.~,
U22
and
U19A
and
t:19B".
"Paragraph
a "
to
"Paragraphs
4.3.7.2.
and
4.3.7.3."
read:
"The
TC
output
pin
15
of
t!
10 •
.•.
"
.
"Paragraph
b(3)"
to
"Paragraph
'::'.3.7
...
(3)"
June
1,
L982
l{A67':Ju/Ga
TABLE
OF
CONTENTS
Paragraph
Title
Page
SECTION
I.
GENERAL DESCRIPTION
1.1
.Electrical
Characteristics
1-1
1.2 "
.'
Mechanical
Characteristics
" 1-2 "
1.3 Equipment Supplied 1-2
......
1.4'
..
Optional Equipment 1·,3·'·
1.5
Reference
Data
1-4
SECTION
n.
INSTALLATION
2.1 Unpacking and Inspection 2-1
2.2
Preparation
for
Reshipment
and
Storage
2-1
2.3
Installation
2-3
2.3.1
Rear
Panel
Jacks,
Switches,
Connectors
2-3
2.3.1.1 A1
OJ
1
power
Input
Connector
and Voltage
Selector
/Fuse 2-5
Block Assembly
2.3.1.2
RF
IN
J 1
Connector
2-5
2.3.1.3 IF OUT
J2
Connector
2-5
2.3.1.4-
AF
OUT
J3
Connector
2-5
2.3.1.5 REF IN/OUT
J7
Connector
2-6
2.3.1.6 A6A1W1J1
Remote
Control
Connector
2-6
2.3.1.7 INT EXT
S2
Slide Switch
2:-6
2.3~1.8
GROUND Lug 2-6
2.3.1.9 PHONES
Jack,
Front
Panel 2-6
2.3.2
Installation
Options 2-7
2.3.3 RA6790/GM
Receiver
Options
Installation
Procedures
2-7
2.3.3.1
IF
Bandwidth
Filters
2-7
2.3.3.2
Remote
Control
Serial Asynchronous
Interface
2-11
2.3.3.3 Independent Sideband
(ISB)
2-15
2.3.3.4- Line Level
Adjustment
2-17
2.3.4 RA6790/GM
Receiver
System
Connections'
2-18
2.3.4-.1 Power Input
Connections
2-18
2.3.4-.2 RF Input
Connector
(J
1)
2-20
2.3.4.3 IF
Output
Connector
(J2) 2-20
2.3.4.4
AF
Output
Connector
(J3) 2-20
2.3.4.5
Reference
Input/Output
Connector
(J7) 2-20
2.3.4-.6
Remote
Control
Serial Asynchronous
Interface
Connections 2-22
(A6AlW1J1)
SECTION
m.
OPERATION
3.1
General
Information
3-1
3.2
Front
Panel
Controls,
Displays/Indicators 3-1
3.2.1 POWER
ON
Toggle Switch 3-1
3.2.2 Manual Tuning Knob 3-1
3.2.3
IF
GAIN
Potentiometer
3-1
3.2.4
AF
GAIN
Potentiometer
3-3
3.2.5
MAIN
LINE LEVEL
Screwdriver-Set
Potentiometer
3-3
i
'.
3.2.6
3.2.7
3.2.8
3.2.9
3.2.10
3.2.11
3.3
3.3.1
3.3.1.1
3.3.1.2
3.3.1.3
3.3.2
3.3.3
3.3.3.1
3.3.3.2
4.1
4.2
4.2.1
4.2.1.1
4.2.1.2
4.2.1.3
4.2.2
4.2.2.1
4.2.2.2
4.2.2.3
4.2.3
4.2.4
4.2.5
4.2.6
4.3
4.3.1
4.3.2
4.3.2.1
4.3.2.2
4.3.2.3
4.3.3
4.3.3.1
4.3.3.2
4.3.3.3
4.3.4
4.3.4.1
4.3.4.2
4.3.4.3
4.3.5
4.3.5.1
4.3.5.2
4.3.5.3
4.3.6
'\
I
TABLE
OF
CONTENTS
(Cont.)
I-LSB LINE LEVEL
Screwdriver-Set
Potentiometer
Lefthand
Keypad
Pushbutton
Switches
Righthand
Keypad
Pushbutton
Switches
Left
(Mode/Meter)
Liquid
Crystal
Display (LCD)
Right
(Frequency
Data)
Liquid
Crystal.Display
(LCD)
. FAULT 'Indicator (LED)
.
Operating
Instructions
RA6790/GM.
Receiver
Options
Installation
Check
-IF Bandwidth
Filter
Installation
Check
Remote
Interface
Option
Check
(Serial Asynchronous
Interface)
ISB
Option
Check
RA6790/GM
Receiver/System
Interface
Check
.LOCAL/REMOTE
Control
Selection
LOCAL
Control
Operation
Checklist
REMOTE
Control
Operation
(Serial Asynchronous
Inte~face)
SECTION IV. CIRCUIT DESCRIPTION
Introduction
. ...
.....
. .
Functional
Theory
of
Operation
Primary
Signal
RF
/IF
/AF
Section
RF
Signal
IF Signal
AF
Signal..
....
. ........ .
Oscilla
tor
Synthesizer:
Section
First
Local
Oscillator
Synthesizer
Second Local
Oscillator
Synthesizer
BFO
Synthesizer
Automat::
~ain
Control
(AGC)
Section
Receiver
::ontro1
Section
Power Supply
Section
BITE
Functional
Description
Detailed
C:-cuit
Description
RF Low
P=...ss
Filter,
A1
First
Mixer,
A2
RF Signal Lowpass
Filter
and Mixer
First
Local
Oscillator
Input
Filter
and Drive
Amplifier
AGe
Controlled
IF
Amplifier
Second Mixer,
AJ
First
IF
Amplifier
First
Local OscUla
tor
Input
Filter
and Drive
Amplifier
AGC Amplifier
Main IF/AF, A
4
IF
Circuits
AF
Circuits
AGC
Control
Circuits
Independent Sideband (ISB),
A5
IF
Circuits
AF
Circuits
AGe
Circuits
First
Local
Oscillator
Synthesizer,
A7
ii
3-3
3-3
3-4
3-4
3-6
·3-6
...
.3-6.
3-7 .
3-7
3-8
3-9
3-9
3-11
3-11
3-18
4-1
4-1
4-1
4-1
4-3
4-4
4-4
4-4
4-5
4-5
4-6
4-6
4-10
4-10
4-12
4-12
4-13
4-13
4-13
4-13
4-13
4-15
4-15
4-15
4-17
4-17
4-19
4-21
4-23
4-23
4-23
4-23
4-25
TABLE
OF
CONTENTS
(Cont.)
4.3.6.1 Operation of Phase Lock Loops
~25
~25
4.3.6.2 Digital Control
4.3.6.3
oscillator
Control
~29
4.3.7 Second
LO
and BFO
Generator,
A8
~33
4.3.7.1
Internal/External
Reference
Frequenc;:y
~33
4.3.7.2
Internal
Mode
~33
4.3.7.3
External
Mode
~35
4.3.7.4 Second Local
Oscillator
~.35·
...
4'.3.7.5 Beat t:requency
Oscillator
(BFO) .4-37:
4.3.8
Receiver
Control
Section
q...;.41
4.3.8.1 Microcomputer Board, A6A2 4-48
4.3.8.2 Serial Asynchronous
Interface,
A6A1 4-53
4.3·.9 Power Supply,
Ala
~57
4.3.9.1 DC Power Supply 4-57
SECTION
V.
MAINTENANCE
5.1
General
5-1
5.2
Preventive
Maintenance 5-1
5.2.1 Inspection for Damage
or
Wear 5-1
5.2.2 Cleaning and Lubrication 5-2
5.3 Maintenance Support Equipment 5-3
5.4 RA6790/GM
Operational
Checkout
and
Fault
Isolation 5-4
Procedures
5.4.1 Initial Check 5-5
5.4.2
BITE
Check
5-6
5.4.3
Al
Low Pass
Filter
Check 5-9
5.4.4
A4
Main
IF
/
AF
Audio Check 5-10
5.4.5
A5
ISB
Audio
Check
5-10
5.4.6
A6A
1
Remote
Serial Asynchronous
Interface
Check 5-10
5.5 RA6790/GM
Performance
Tests 5-10
5.5.1 Frequency Tuning 5-12
5.5.2 Frequency Display 5-12
5.5.3 Frequency Stability 5-13
5.5.4 Frequency
Calibration
Resolution 5-13
5.5.5 RF Gain
Control
5-13
5.5.6 Final
IF
Frequency 5-13
5.5.7 Fixed/Variable BFO Operation 5-14
5.5.8 Audio
Output
Power 5-15
5.5.9 Audio Distortion 5-15
5.5.10 Operation
After
Restoration
of
Power 5-15
5.6 Board Level
Fault
Isolation 5-16
5.7
Receiver
Assembly and Disassembly
Procedures
5-16
5.7.1 Preliminary
Procedure
5-16
5.7.2 Top and Bottom Covers 5-16
5.7.3 Al Module Removal 5-17
5.7.4 Al Module Installation 5-17
5.7.5
A2
Module Removal 5-19
5.7.6
A2
Module Installation 5-19
5.7.7 Module Removal 5-19
5.7.8
A3
Module Installation 5-20
5.7.9
A4
Module Removal 5-20
iii
TABLE
OF
CONTENTS
(Cont.)
5.7.10
A4
Module
Installation
5-21
5.7.11
A5
Module
Removal
5-21
5.7.12
A5
Module
Installation
5-21
5.7.13 .
A6
Module
Removal
5-21
5.7.14
A6
Module
Installation
5-22
5.7.15
A7
Module
Removal
5-23
5.7.16
A7
Module·
Installation
.5-23
5.7.17
A8
Module
Removal
5-24-
:
.'
5.7:18 .
A8
Module
Installation
5-24-
.
5.7.19
A9
Module
Removal
5-24
5.7.20
A9
Module
Installation
5-28
5.7.21 AlO Module
?~emoval
5-28
5.7.22 AlO Module
installation
5-29
5.7.23 Edgelight Assembly and
Removal
Procedures
5-29
5.7.23.1
Edgelight
Re:7loval 5-29
5.7.23.2 Edgelight
In"::Jlation
5-29
5.7.24 Keypad
Removal
and
Installation
5-30
5.7.24.1 Keypad
Removal
5-30
5.7.24.2 Keypad
Installation
5-30
5.7.25
IF
Bandwidth
Filter
Removal
and
Installation
5-30
5.7.25.1 Bandwidth
Filter
Removal
(Optional Plug-In
Crystal
5-30
Filters
Only)
~
..
5.7.25.2 Banawidth
Filter
Installation
(Optional Plug-In
Crystal
5-30
Filters
Only)
.'
5.8
Operational
Fault
Symptom
Chart
5-31
SECTION
VI.
REPLACEMENT PARTS LIST
6.1
In
troduction
6-1
SECTION
Vll.
SCHEMATIC DIAGRAMS
7.1 In
troduc:
;on 7-1
SECTION
VIll.
DIFFERENCE OATA
8.1
In
forma
tion 8-1
8.3 Equipment Modifications 8-1
8.5 Scope
of
Difference
Data
8-1
8.;
Operation
8-1
8.9 AGC Level
Return
8-1
8.10
Parts
List 8-1
8.12
Parts
List
Description
8-1
8.14 Usable
On
Code
Effectivities
8-2
8.15
Parts
Ordering
8-2
8.16
Parts
Suppliers
8-2
8.17
Schematic
Diagrams
8-2
iv
LIST
OF
ILLUSTRA
nONS
Figure
Title
Page
1-1 RA6790/GM HF
Receiver
Overall
View 1-0
1-2
International
Reception
·Mode Codes 1-5
2-1 Iristallation Drawing, RA6790/GM HF
Receiver
2-0
2-2 Packaging
Details,
RA6790/GM HF Re.ceiver , ' 2-2
2-3 ,RA6790/GM HF
Receiver
Rear
Panel
Jacks,
~witches
and
"2-4
Connectors
" :
2-4
Location
of
.IF
Bandwidth
Filter
Slots
2-9'
'
..
",
2-5 -
Location
of
Fitters
and
Jumpers,
A4 Assembly 2-10
2-6
Receiver
Options
Installation
Detail
2-12
2-7 A6A2 Circuit
Card
Assembly
Jumpers
2-13
2-8 A6A 1
Circuit
Card
Assembly
Jumpers
(Serial Asynchronous 2-14
Interface.)
2-9 Mating A6A1 and A6A2
Circuit
Card
Assemblies 2-16
2-10 RA6790/GM
Rear
Panel System
Connections
2-19
2-11
Remote
Control
Connector
Pin Designations
and
Functions
2-24-
3-1 RA6790/GM
Front
Panel
Controls
and
Indicators
3-0
3-2
Front
Panel
Displays
Detail
3-2
3-3
Data
Character
Format
3-20
4-1 RA6790/GM
Functional
Block
Diagram
4-0
4-2 Basic
Receiver
Functional
Breakdown, 4-2
4-3
First
Mixer,
Functional
Block Diagram
4-14-
4-4 Second Mixer,
Functional
Block
Diagram
4-16
4-5
A4
IF
Circuits,
Functional
Block Diagram
4--18
4-6
/\4
AF
Circuits,
Functional
Block Diagram 4-20
4-7
A4
AGC
Circuits,
Functional
Block Diagram 4-22
4.-3
ISB,
Functional
Block
Diagram
4-24-
4-9 Typical Phase Lock Loop 4-26
4-10 Fir
st
Local
Oscillator,
Digital,
Functional
Block
Diagram
4-28
4-11
Frist
Local
Oscillator,
Analog,
Functional
Block
Diagram
4-30
4-12
Detailed
Timing
Diagram
4-32
4-13 Second Local
Oscillator,
Functio"nal Block
Dia~ram
4--34
4-14 Waveform Diagram: Phase
Comparator
"
4--36
4-15 BFO
Functional
Block Diagram
4--38
4-16
Receiver
Control,
Functional
Block
Diagram
4-42
4-17 Encoder
Output
Signals 4-44
4-18 Liquid
Crystal
Display
Control
Signals 4-46
4-19
Central
Processor
Unit, Timing Signal
Diagram
4--50"
4-20
Central
Processor
Unit,
Functional
Block
Diagram
4--52
4-21 System Memory
Interface,
Functional
Block Diagram
4--54
4-22 UART
Transmitter
Functional
Block
Diagram
4-56
4-23 UART
Receiver
Functional
Block Diagram
4--56
5-1
Standard
Test
Equipment
Configuration
5-11
5-2 Typical Signal Levels, RA6790/GM HF
Receiver
5-18
5-3
Front
Panel A9, Wiring
Detail
5-26
5-4
Front
Panel (Assembly,
Partially
Disassembled) 5-27
v
6-1
6-2
6-3
6-4
6-5
6-6
6-7
6-8
6-9
6-10
6-11
6-12
6-13
6-14
6-15
6-16
6-17
6-18
6-19
6-20
-
6-21
6-22
6-23.
• 6-24.
6-25
6-26
6-27
6-28
7-1
7-2
7-3-
7-4
7-5
. 7-6
7-7
7-8
7-9
7-10
7-11
7-12
7-13
',.
7-14
8-1
Change
4
LIST
OF
ILLUSTRA
nONS
(Cont.)
Top View
Bottom
View
Location
of
Modules, Top View
Location
of
Modules,
Bottom
View
-Low
Pass
Filter
Assembly,
Al
Component
Location,
Al
First
Mixer Assembly A2
Component
Location,
A2 .
-Second Mixer
Assembly,
A3
Component
Location,
A3
Main
IF/AF
Assembly,
A4
Component
Location,
A4
ISB
Assembly, A5 (Optional)
Component
Location,
A5
Microcomputer
Assembly, A6
Asynchronous
Interface
Assembly,
A6AI
Component
Location,
A6AI
Microprocessor
Assembly., A6A2
Component
Location,
A6A2
First
LO
Synthesizer
Assembly, A7
Component
Location,
A7
Second LO/BFO
Synthesizer
Assembly, A8
Component
Location,
A8
Receiver
Control
Assembly, A9
Component
Location,
A9
Power Supply Assembly,
Ala,
Top View
Component
Location,
Ala
Component
Location,
AlOA2
Schematic
Diagram,
RF
Low Pass
Filter
Al
.
Schematic
Diagram,
1st
Mixer, A2
Schematic
Diagram,
2nd Mixer,
A3
Schema
tic
Diagram,
Main IF/ AF, A4
Schematic
Diagram,
ISB, A5 (Optional)
Interconnection
Diagram,
Microcomputer
Assembly, A6
Schematic
Diagram,
Serial
Asynchronous
Interface,
A6A1
Schematic
Diagram,
Microcomputer,
A6A2
Schematic
Diagram,
First
LO
Synthesizer,
A7
Schematic
Diagram,
Second LO/BFO
Synthesizer
AS
Schematic
Diagram,
Receiver
Control,
A9
Schema
tic
Diagram,
Liquid
Crystal
Display
Lamps
Schematic
Diagram,
Power
Supply,
Ala
Interconnection
Diagram,
RA6790/GM HF
Receiver
Microprocessor
Circuit
Card
Assembly (A6A2)
Schematic
Diagram
vi
6-2
6-3
6-4
6-5
6-9 I
6-10.
6-13 '
. 6-'14:,-
. .
6-17
6-18
6-23
6-24
6-31
6-32
6-37
6-39
6-40
6-43
6-44
6-47
6-48
6-53
6-54
6-59
6-60
6-65
6-66
6-68
7-3
7-5
7-7
7-9
7-21
7-25
7-27
7-31
7-35
7-45
7-51
7-57
7-59
7-61
8-3
LIST
OF
TABLES
Table
Title
Page
1-1 RA6790/GM HF
Receiver
Specifications
1-6
2-1 RA6790/GM Bandpass
Optional
Filter
List
2-7
2-2 Link Designations,
Remote
Control
Interface
2-11
2-3 AF OUT
J3
Pin
Connections
2-21
2-4
External/Internal
Link Options
2,"21
--
2-5
Data
Connection
Interface
Compatability
2-23 -.
2-6
Interface
Connector
Baud
Rate
Selection
2-23-
2-7 A6A 1 Link
Configuration
2-23
2-23
2-8
Parity
Select
3-1 ASCII
Character
Codes 3-21
5-1
Preventive
Maintenance
Schedule 5-1
5-2
Maintenance
Support Equipment 5-3
5-3 BITE
Error
Code
Identification
5-7
5-4 Tuned
Frequencies
5-12
5-14-
5-5 BFO
Test
Values
5-6
Opera
tionally Based
Fault
Symptom
Chart
5-32
6-1 RA6790/GM
Receiver
Assembly
6-6
6-2 Low Pass
Filter
Module,
Al
6-11
6-3 LPF
Circuit
Card
Assembly,
AlAI
6-12
6-4-
First
Mixer
Circuit
Card
Assembly, A2 6-15
6-5 Second Mixer
Circuit
Card
Assembly,
A3
6-19
6-6
Main
IF/AF
Circuit
Card
Assembly, A4 6-23
6-7
ISB
Circuit
Card
Assembly,
A5
6-29
6-8 Microcomputer Assembly,
A6
6-32
6-9 Serial Asynchronous Iriterface
Circuit
Card
Assembly, A6Al 6-35
6-10 Microprocessor
Circuit
Card
Assembly, A6A2 6-39
6-11
First
LO
Synthesizer
Circuit
Card
Assembly,
A7
6-43
6-12 Second LO/BFO
Synthesizer
Circuit
Card
Assembly,
A8
-6-49
6-13
Receiver
Control
Assembly,
A9-
6-55
6-14 LCD Lamp
Circuit
Card
Assembly, A9A2 6-57
6-15 Power Supply Assembly,
Ala
6-61
6-16
20
Volt
Regulator
Assembly, AIOA2
6-62
8-1
Parts
List, Microprocessor Assembly, A6A2 8-7
vii
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I
SECTION
I
GENERAL
DESCRIPTION
1.1 ELECI'RICAL CHARAcrERISTICS
The
RA6790/GM
HF
Receiver,
shown
in
Figure 1-1, is a fully synthesized, microcomp·liter-·
".
based,
tunable~
solid-State receiver designed
to
provide
reception
capabilities
for
CW(AI), AM(A3), .
LSB/USB (A3J),
FM(F3)
and
ISB (A3B-Optional), emiSsions over
the
frequency range
of
0.5 MHz to
30
MHz. Frequency
tuning
is
accomplished
by
either
keyboard
entry
(numerical keypad)
or
single
knob
control
for
continuous
tuning
with selectable rates, FAST
(1000
Hz), SLOW (30 Hz),
FINE
(1
Hz) increments
and
BFa
continuous
in
10
Hz increments.
Front
panel indication
of
frequency
data
are Qresented as 8 LCD (Liquid Crystal Display) digits
of
tuned
frequency and 3 digits
and
sign
readout
of
BFa
data
relative
to
IF
Center
:!:8.0 kHz.
Other
front
panel displays are:
RF
Meter,
AF
Meter, Bandwidth, AGC, Mode,
Remote
and
Fault
indication
(LED). Additionally, provision
is
made
on
the
front
panel, selectable
by
use
of
the
RF
Gain Control,
to
manually
control
the
AGe
threshold anywhere within the range
of
110 dB above
the
preset
AGC threshold level.
Full
remote
control
(optional)
of
all Receiver parameters is available
by
either;
(1)
serial
" asynchronous,
ASCII
character-arientedwithstrapselectable
baud
rate
of
50
baud
to
19.2 kilobaud,
selectable MIL-STD-188C
or
EIA
Standard
R5-232-C/R5-422/R5-423 compatible, 2-byte-serial, (2)
byte-serial
bit
parallel IEEE
standard
488C-1978 compatible
or
(3)
other
user specified interface
fonnat.
. Built-In
Test
Equipment(BlTE)
is
provided
in
the ReceiyercirCuitry
to
find,testand
report operiltiomil
stanis
to"
the
lowest replaceable
unit
(LRU)
wfth
both
local and
remote
notification.
The internal frequency tuning circuitry
of
the
Receiver includes a single loop digital 1st LO
Synthesizer. phase lock loop
2nd
LO
and
BFa
Synthesizers, which in
combination
detennine
tuned
frequency to a resolution
of
I Hz. The synthesized
BFa
tunes::8
kHz in 10 Hz increments with a
pushbutton
selectable
parameter
for
immediate zero reference.
The Receiver is designed
to
operate
with
up
to
seven
IF
fJ.1ters,
using slots provided
on
the Main
IF/AF
circuit card assembly. Unless otherwiSe sp.ecified,
the
Receiver is factory equipped
with six mechanical fIlters
and
one
bypass link
to
provide seven selectable bandwidths. Audio
outPut
of
the Receiver
is
either
through
a PHONES
jack
on
the
front
panel
or
through
an
AF
OUT
connector
on the rear panel.
The
PHONES
jack
provides a
nominal
10 milliwatts
into
600
ohms
and
is
adjustable:
through the AF
GAIN
control
on
the front panel.
'The
AF
OUT
connector
provides a nomina11
milliwarL
600
ohm·balanced
line
output
and
an
output
of
nominally 1 Watt in 8 ohms, suitable for an 8
ohm
speaker.
Rear panel features include
BNC
connectors for providing
the
Receiver second
IF
455
kHz
output.
supplying
or
receiving external/internal reference signals used in
conjunction
with a slide
switch. 52. A 25-pin D-type
connector
provides audio,
AGe
and fault
status
outputs
while an N-type
connector
provides RF
input
from an external antenna.
An
optional
remote
control
interfac.e
connector.
either round 26 pin
(188C/232C/422/423)
or
elongated 24 pin (IEEE-488),
is
provided when specified. A
standard 3 prong male
connector
for
connection
'Jf an ac line
cord
completes
the rear panel assembly.
Input
signals from the antenna are connected
to
a
low
pass fIlter which rejects signals
above
30
MHz.
The
output
of
this filter
is
then
coupled
to
a
mixer
stage where the RF signal
is
mixed with the synthesized local oscillator signal.
The
frequency
of
the local oscillator can be varied
I-I
from 40.955
to
70.455
MHz.
This signal
is
brought through a fIlter and
AGe
controlled amplifier
stages to the second mixer.
The 40.455
MHz
first IF
is
combined with the
fIXed
40
MHz
output
from the second oscil-
lator synthesizer to produce a 455 kHz second IF. After amplification, this second IF
is
routed to the
plug-in 455 ,kHz filters which provides the main Receiver selectivity:
A second AGC-controlled amplifier follows before demodulation takes place. In the SSB/
CW
/
AM
modes, a product. synchronous detector
is
used. In the
CW
mode, the BFO synthesizer may
be
varied
±8
kHz (above 'or
~elow
the
.155
kHz
c.enter frequency) through front panel controls.
For.
FM
reception, the 455 kHz second IF
is
input
to
a limiting amplifier and subsequently to a separate
FM
detector.
A:ll
three outputS from the synthesizers are referenced
to
an internal 5
MHz
standard
frequency source,
or
to
an external reference
of
1
MHz.
The demodulated signal
is
fed through an
audio crosspoint swit.:h to separate AF amplifiers which provide outputs for a 600 ohm line, a head-
phone jack, and an external loudspeaker.
For
ISB
operation, the optional
ISB
board provides the
LSB
signal path, while the main
IF/AF board provides the
USB
signal path. The
LSB
component
of
the 455 kHz second IF
is
processed
through similar circuitry with the common
BFO
synthesizer providing the remserted carrier for de-
modulation. A separate audio amplifier provides a 600 ohm line output.
All
command signals, whether from the front panel controls or from
an
extended
or
remote
operating,position, are processed by the microcomputer assembly. Two separate buses carry control
data and address information to and from the microcomputer control assembly
to
the synthesizers for
frequency selection, and to the appropriate switching circuits controlling the different operating modes.
1.2 MECHANICAL CHARACTERISTICS
The RA6790/GM Receiver mounts in a standard 19-inch (48.3 cm) equipment rack, and
OCCUples
5,25 inches (13.33 cm)
of
vertical space,
19
inches (48.3 cm) wide, 18.5 inches (47 cm) deep
and weighs 30 pounds (13.5 kg).
A rigid, die-cast full width chassis
is
used
as
the base for the main frame
of
the Receiver.
~10unted
within compartments on the undersIde
of
this chassis are the mixer boards and the frequency
generation system. The input low pass fllter, main IF/AF,·optional
ISB
IF/AF and power supply ,
modules are'located on the top surfaces
of
the die-cast chassis while the control and digital I/O mod-
ules
are attached on the Receiver main frame.
All
modules are accessible for maintenance and can
be
removed or replaced using simple hand tools without the use
of
a soldering iron.
Manual controls and indicators for operation and monitoring
of
the Receiver are contained
on
the front panel while input/outputjacks and connectors are provided on the rear panel. A PHONES
jack. for audio connection to optional headphones.
is
contained on the front panel for convenient
ac-
cess.
A primary power fuse
is
accessible from the rear panel.
1.3 EQUIPMENT SUPPUED
The equipment supplied consists
of
the following:
1.
RA6790/GM HF Receiver
2.
WI8, Primary Power Input Cable
3. Connector, Mating for
13
1-2
4. Six Mechanical Filters.
Unless otherwise specified
the
fIlters shall conform
to
Racal
part
numbers 07883-1
thru
07883-6. Refer
to
Paragraph 1.4, Item
#2
below for details.
1.4 OPTIONAL EQUIPMENT
The following optional equipment is available for use with
the
RACAL RA6790/GM HF
Receiver. Additional information regarding these and other options should be made through
your
RACAL representative
or
directly
to
RACAL Communications, Inc.,
Roc~e,
Maryland, USA.
1,
2.
fudependent Sideban4 Module (lSB,
AS);
Selectable
IF
Bandwidth Mechanical Filters:
Shape
Factor
Racal
Bandwidth Description 3 dB:
60
dB
Number
1.
0.3
kHz
. Symmetrical BPF 1:6.7 07883-1
2. 1.0
kHz
Symmetrical BPF 1:4.5 07883-2
3. 3.2
kHz
Symmetrical BPF 1:2.7 07883-3
4. 4.0
kHz
Symmetrical BPF 1:2.5 3600001
5.
5.0
kHz
Symmetrical BPF 1:2.5 3600002
6.
6.0
kHz
SymIp.etrical BPF 1:2.3 07883-4
7.
450
Hz
to
3000
Hz
ISB/USB BPF 1: 1.92 07883-5
8.
450
Hz
to
3000
Hz
$ ISB/LSB BPF
1:
1.92 07883-6
9.
350
Hz
to
2700
Hz
USB
BPF
1:
1.66 08669
10.
300
Hz
to
2200
Hz
USB
BPF
1:
1.97 08771
Note
that
input and
output
matching capacitors are required with mechanical
fIlters only, contained on assembly A4.
3.
Selectable IF Bandwidth Crystal Filters:
The Receiver may be operated with one
to
seven different crystal bandwidth fIlters.
There are currently a total
of
23
different fIlters available; however, depending on
Receiver configuration, some fIlters are mandatory. (Refer
to
the Installation Section
of
this manual for defmition
of
IF Bandwidth Filter Installation.)
Bandwidth
1.0
kHz
3.0
kHz
6.0 kHz
1.0
kHz
3.0 kHz
.6.0
kHz
0.125 kHz
0.4
kHz
1.2 kHz
6.8
kHz
350
Hz
to 3050
Hz
350
Hz
to
3050
Hz
0.4 kHz
Description
Symmetrical BPF
Symmetrical BPF
Symmetrical
BPF
Symmetrical BPF
Symmetrical BPF
Symmetrical BPF
Symmetrical BPF
Symmetrical BPF
Symmetrical BPF
Symmetrical BPF
ISB/LSB BPF
ISB/USB
Symmetrical BPF
1-3
-
...
.--:,.-
Shape
Factor
Differential Racal
3 dB:
60
dB
Delay
/lS
Number
1:6
1:6
1:6
1:2.5
1:2.5
1:2.5
1:5.33
1:6.2
1
:6
1:3.3
1:
1.6
1:
1.6
1:2.5
25
13
10
1080
360
180
800
800
2000
3600003
3600004
3600005
3600006
3600007
3600008
08699
08406
08407
08408
08409
08410
08411
..
",
1.2 kHz
3.24 kHz
6.8 kHz
16.0 kHz
0.5 kHz'
1.0 kHz
2.0 kHz
3.0 kHz
6.0 kHz
0.075 kHz
Symmetrical BPF
Symmetrical BPF
Symmetrical BPF
Symmetrical BPF
Symmetrical BPF
Symmetrical BPF
Symmetrical BPF
Symmetrical
BPF
Symmetrical BPF
Symmetrical BPF
4. Remote Control Options (A6Al):
1:2
1:1.33
1:2
1:2
1:6
1:6
1:6
1:6
1:6
1:6.67
1(Y.)0
1000
.1000
40
80
40
20
20
20
08412
08413
08414
08415
08416
08417
08418
08419
08420
08589
, '
a.
-R5-232/Rs-422/R5-423 Serial Asynchronous Remote Interface Module
b.
IEEE 488C-1978 Compatible;
.
5.
Improved internal frequency standard
±3
parts
10-
9;
6.
RF Amplifier for greater receiver sensitivity;
7.
LF/MF/HF low frequency -
10
kHz to 30 MHz;
8.
Broadband
IF
output.
1.5 REFERENCE DATA
Table
1-1
identifies the technical specifications for the RA6790/GM HF Receiver. The
Receiver provides reception capabilities for
CW
(Al),
AM
(A3), LSB/USB (A3J),
FM
(F3) and
optionally
ISB
(A3B) operation. Figure
1-2
depicts the International Reception Mode Codes.
1-4
-
I
VI
Complete
Designation
Example:
2
Bandwidth in
kllZ-----------
Type
of
Transmission
A
=AM
F = FM
P =
PCM
Abbreviations:
AM
=
Amplitude
Modulation
CW
=
Continuous
Wave
FM =
Frequency
Modulation
(or
Phase)
FSK =
Frequency
Shift
Keying
ISB =
Independent
Sideband
LSB =
Lower
Sideband
MCW
=
Modulated
Continuous
Wave
PCM
= Pulse
Coded
Modulation
SSB = Single
Sideband
USB =
Upper
Sideband
DSB = Double
Sideband
A 2 H
Purpose·
o =No
modulation
I =
Telegraphy
(on-off)
2
:;:;
Telegraphy
(modulation)
3 =
Telephony
4 = Facsimile
5 =Television
6 = Duplex Telegraphy
7 = Multichannel Telegraphy
9 =
None
of
the
above
Figure 1-2.
International
Reception
Mode
('odes
Supplementary
Characteristics
A = Single Sideband
reduced
carrier
B =
Two
independent
sidebands
C = Single sideband vestigial
D =
AM
pulse
E = Pulse
width
modulation
H = Single sideband, full
carrier
J = Single sideband,
suppressed ,?arrier
(None)
(None)
= Double sideband, full
carrier.
. I
TABLE 1-1.
RA6790/GM
HF
RECENERSPECIFICATIONS
Frequency
Range
Frequency
Resolution
Frequency
Tuning
Frequency Indication
Frequency Sta9i1ity
Detection Modes
Gain
Control
Modes:
AGC
0.5
kHz
to
29.999999
MHz
1 Hz
increment
By
keyboard
entry
or
continuous
tuning
with
seiectable rates,
FAST
(1000
Hz),
SLOW
(30
Hz),
and
FINE
(1
Hz)
increments; .
BFO
continuous
in 10 Hz increments.
8 digit electronic
readout
of
tuned
frequency
to
1 Hz; 3 digit
and
sign
readout
of
BF»
relative
to
IF
center
±8.0 kHz.
±5 parts
in
the 108
per
100C
temperature
increment
over the
range
of
OOC
to
50
0C using
internal
5 MHz reference oscillator.
Provision for an external
1,
5
or
10 MHz reference
input/output.
odBm nominal
into
50
Ohms.
CW/Al
Continuous
Wave; CW/A2
Modulated
Continuous
Wave;
USB/LSB
(upper/lower
sideband) A3A, A3H, A3J, A2A, A2H,
A2J;
AM/
A3 Amplitude
Modulation;
A4
(Facsimile) ISB/A3B
Independent
Side Band
(optional);
FM/F3
Telephony.
Control
Range: An increase
of
110 dB above AGC threshold
will result in a change
of
output
of
less
than
3 dB.
Threshold Range (preset):
-113
dBm
to
-100
dBm
Time Constants:
Attack:
Decay:
Short
~edium
Long
20
msecs
<
30
msecs
200
+
100
msecs
3.75 seconds ±
1.
25 msecs
y{anuall
Automatic
Gain
Control
Provision
is
made
on
the
front
panel
to
select.
and
by
use
of
the
RF Gain Control, to manually
control
the AGC threshold any-
where within the range
of
110 dB above
the
preset AGC threshold
level.
Input
Impedance
50
ohm
nominal, 2:1 VSWR
Type
N
Connector
Synthesized BFO
455
±8
kHz in 10 Hz steps
Noise Figure <
15
dB
Dynamic Range
RF:
> i
80
dB/Hz
1-6
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