TFT 884 User manual

STEAM POWERED RADIO.COM
l
l
1
1
1
1
1
~
1
I
1
l
1
~
1
1
l
l
I
OPERATION
AND
TECHNICAL
MANUAL
MODEL 884
FM
MODULATION
AND
STEREO MONITOR
,

STEAM POWERED RADIO.COM
._
PIN 5004-0884
May 25,.d988
Revision A
Equipment Serial No. _ _ _
Shipping
Date ____ _
OPERATION AND TECHNICAL MANUAL
MODEL 884
FM MODULATION
AND STEREO MONITOR
TFT, Inc.
3090 Oakmead Village Drive
Santa Clara, CA 95052
TEL [phone]
TWX 910-338-0584
FAX [phone]

STEAM POWERED RADIO.COM
I
I
I
I
I
I
I
I
I
I
I
I
I
I
~
I
I
'/
I
I
MODEL
884
TFT
OPERATION
MANUAL
ADDENDUM
MANUAL
REVISION
LEVEL~
EFFECTIVITY
SIN
------
IMPORTANT
MANUAL
CHANGES
The
following
drawings
and
Parts
List
replace
the
previous RF Preselector
drawings
and
Parts
List:
·
Drawing
Description
1.
RF
Preselector
Bd.
2.
RF
Preselector
Bd.
Reason
for
change/Changes
~
New
generation RF Preselector
Board
has
been installed
in
the
884
unit.
New
ge
·neration
RF
Preselector
Board
has
been installed
in
the
884
unit.
3.
RF
Preselector Parts
List
To
reflect
the
new
RF Preselector
Board,
reyised
Parts
List.
5.
FM
Demodulator
Bd.
To
accomodate
the
new
RF Preselector
6.
FM
Demodulator
Bd.
7.
FM
Demodulator
Parts
List
8.
884
Block
Diagram
9.
Interconnect
Diagram
Board,
changed
R181
from
100n
to
100.
To
accomodate
the
new
RF Preselector
Board,
changed
R181
from
100n
to
10n.
Revised
Parts
List
to
reflect
the
change
in
the
value
of
R181.
Revised
to
reflect
new
RF Preselector
Board.
Revised
to
reflect
new
RF Preselector
Board
10.
Revised
title
page
for
Revision
B.
Drawing
No.
6601-3713,
Rev,
A
6608-3713,
Rev.
A
6608-3713,
Rev.
A
Parts
List
6601-3645,
Rev
B
6608-3645,
Rev
B
6608-3645,
Rev.
B
Parts
List
6600-2597
6600-2527,
Rev.
B
11.
Revised
Table
of
Contents
to
reflect
new
RF
Preselecfor
Board
and
to
correct error
in
drawing
numbers
for
the
FM
Demodulator
Board.
12.
Revised
text
in
Paragraph
4.2
to
reflect
the
new
RF Preselector
Board.
Date
2-22-89
form
No.
5300-0268

STEAM POWERED RADIO.COM
\
PIN
5004-0884
February
21,
1989
Revision
B
Equipment Serial
No,
__
_
Shipping Date
____
_
OPERATION
AND
TECHNICAL
MANUAL
MODEL884
FM
MODULATlO.N
AND
STEREO MONITOR
TFT,
Inc.
3090
Oakmead Village Drive
Santa Clara,
CA
95052-8088
TEL [phone]
1WX
910-338-0584
FAX
(408)
727-5942

STEAM POWERED RADIO.COM
Model
884
Figure
3-1
SECTION 4
4.1
4.2
4.3
4.4
4.5
SECTIONS
5.1
SECTION
6A
Figu~
No
.
6-1
6-2
6-3
6-4
6-5
6-6
6-7
6-8
6-9
6-10
3.4.8
FM
Noise ...........
..
,.................................................,
...,
...............
.
....
, 3-7
3.4.9
Distortion ............,.............................................................................
3-8
3.4.10
Pilot
Frequency
........................................................
.
.....
.
...
..
...........
3-8
3.4
.
11
Peak Modulation.............................................................................
3-8
3.4.12
Synchronous and Asynchrono~s
AM
Noise ...............................
3-9
Model
884
Front and Rear Panel Illustration
THEORY OF OPERATION
6600-2523
General
Discussion
(Figure
6-1)
.
..
............................................................
4-1
RF Preselector
Al
(Figure
6-3)
................................................................
4-1
FM Demodulator
A3
(Figure
6-5)
.........
........
...................................
.
.....
4-2
FM
Stereo
A4
(Figure
6-
7)
........................................................................
4-3
Display Driver
A6
(Figure 6-10) .............................................................
4-4
MAINTENANCE
Calibration
.............................................
.........................
......
.
.....
..
.................
5-l
5.1.1
Meter
Calibration
............................................................................
5-1
5.1.2
Peak Modulation Calibration ........................................................
5-1
5.1.3
Stereo Separation ~djustment .......................................................
5-2
.DIAGRAMS
AND
SCHEMATICS
Title
Model
884
Block Diagram
Model
884
Interconnect Diagram
RF Preselector
Al,
Schematic
RF Preselector
Al,
Assembly
FM
Demodulator
A3,
Schematic
FM
Demodulator
A3,
Assembly
FM
Stereo
A4,
S<;hematic
FM
Stereo
A4,
Assembly
Display Driver
A6,
Schematic
\Display Driver
A6,
Assembly
\
w
Drawing
No.
6600-2597
6600-2297
6601-3713
6608-3713
6601-3645
6608-3645
6601-3595
6608-3595
6601-3410
6608-3410

STEAM POWERED RADIO.COM
SECTION 4
THEORY
OF
OPERATION
4.1 General Discussion (Figure 6-1)
Modcl884
The
Model
884
FM
Modulation
and
Stereo Monitor
contains
a
low
level
RF preselector,
FM
monitor, stereo
baseband
monitor,
and
a peak detector. Four major circuit boards per•
form
these
functions:
RF
Preselector A
1,
FM
Demodulator
A3,
FM
Stereo
A4,
and
Display
Driver
A6.
The
block
diagram,
Figure
6•
l,
is
located
in
Section
6of
this
manual.
RF input
from
either transmitter
or
antenna enters the
884
rear panel
and
is
routed
to
RF
Preselector A
1.
Here
the
signal
is
padded through
the
attenuated circuit to a balanced
mixer.
The
900
kHz
IF
signal
is
sent to a
low
pass
filter.
This
IF
is
then routed to the
Demodulator
Board
A3.
.
FM
Demodulator
A3
receives
the
900
kHz
IF,
demodulates
the
signal,
and
delivers a pulsed
output
that
is
filtered
and
amplified.
The resulting
signal
is
filtered
and
routed to
the
FM
Stereo
Board.
On
A4
the
composite
signal
is
filtered
and
returned
to
A3
and
to
the
front
panel
monitors
and
test
outputs.
Separation adjust
is
also
performed
on
A4.
Positive
and
negative
modulation
are
used
to
drive
the
front
panel
PEAK
flashers
on
A6,
the
Display
Driver.
Each
modulation
peak
is
compared
in
a
peak
detector
to
a
voltage
olr
tained
from
a
constant
current
source
by
means
of
resistances
selected
by
pushbutton
switches
on
the
·
PEAK
MODULATION
flashers.
The
pulse
outputs produced
by
the
peak
detect0rs
when
modulation
exceeds
user
preset values are
applied
to
the
front
panel LED
flashers,
which
light
for
approximately
2 seconds..
4.2
RF
Preselector
Al
(Figure
6-3)
The RF input
to
the
monitor
comes
from
the
sampling
point of the transmitter
as
a high;
level
signal
or
from
an
antenna. The
high
input
level
enters
the
884
through the rear panel
RF INPUT HI
LEVEL
(50
ohm)
connector
J7.
The
signal
is
fed
through the adjustable
at•
tenuator
HI
LEVEL
RF
INPUT
SET
R2
on
the rear
panel.
This
high
level
input
signal
is
adjusted
for
a
constant
level
and
goes
to
the
AM
NOISE
detector,
which
is
routed
to
the
front
panel
TOTAL
MODULATION/TEST
meter. The
high
level
also
lights
the
rear panel
HI
LEVEL RF
INPUT
SET
LED
(21)
when
the
~F
level
adjust
is
correct. The RF
signal
goes
to
the
ANTENNA
INPUT
jack
(24
).
4-1

STEAM POWERED RADIO.COM
Model 884
When an antenna signal is fed to the ANfENNA INPUT, JS, it is routed to Zl and mixed
with the frequency synthesizer L.O. (local oscillator) and becomes a 10 .7 MHz IF. This IF
is fed to linear phase filter FLl and then the lF amplifier Ul. At Ul, the level detectors
detect the antenna
level as the de component. When detected, the antenna level is fed to
US, the mute detector. The factory sets the mute level for 40 µY RF input. When the mute
level is less than the factory •set level, US shuts off the demodulator. This level also goes to
the rear panel terminal strip, TB 2.
The IF from Ul is also fed to Tl, the IF transformer, and then to U17, the balanced mixer .
The 10 .7 MHz signal mixes with the second LO., 10 MHz, from the timebase crystal oscil-
lator. The mixed signal goes to the low pass filter which looks for the 700 kHz second IF.
This 700 kHz is routed to the Q7 and Q8 switch and fed to A3, the FM Demodulator Board.
The 10 MHz timebase is crystal-controlled oscillator Yl and its associated components. It is
the reference for the PLL frequency synthesizer and is also the second LO .
4.3 FM Demodulator A3 (Figure 6-5)
The 900 kHz IF signal which is applied to the FM Demodulator Board A3 through a relay
to a pulse counting FM demodulator circuit. The limiting amplifier, Ul, is driven into
saturation
to provide limiti ng. U2 is a one -shot multivibrator acting as a pulse averaging dis-
criminator. It delivers a pulsed output whose frequency is the same as the IF but with a
fixed pulse width. The duty cycle in the output pulse train varies with the modulation and
the audio is recovered by passing the discriminator output through a low pass filter. Transis-
tors Ql thru Q4 make up the clamping circuit.
The
low pass filter consists of 1.2 and L3 and amplifier U7. This ci rcuit provides a flat
response to 100 kHz and linear phase in order to give good stereo measurements. The fre•
quency response rolls off after 100 kHz to eliminate any resiual 900 kHz. Amplifier UlO
raises the audio level to 1 Vrms.
The monitor calibration circuit consists of U3 thru U6. The 358 kHz output of the timebase
is divided down to 4.48 kHz, which is then used to gate the 200 kHz on and off at a 4.48 kHz
rate. This simulates a 100% modulated input. When the front panel METER CAL switch
is depressed, this calibration si gnal is fed into limiting amplifier Ul and discriminator U2 in
place of the 900 kHz IF. After passing through a 7.5 kHz calibration low pass filter, it is
amplified by U8, which is adjusted by CAL LEVEL ADJUST R29 to give a 100% reading
on the TOTAL MODULATION/fEST meter. The signal can also be used to check meter
and flasher calibration. The circuit is very stable and can be · used to correct drifts in the
one -shot discrimin ator U2 and the meter amplifiers.

STEAM POWERED RADIO.COM
Model
884
FM
Modulation and Stereo Monitor
RF Preseledor Board
CKT,
REF.
DESCRIPTION
C004
CAP
CER
(2),
1MF
C~:058X
~:
C005
CAP
CER
0.1MF
CK058X ' K
C006
CAP
CER
0.001MF
Cf
<
05
C007
CAP
CER
, 01MF C~~058X
1,:
C011
CAP
CER
0
.1MF
o
::
05BX K
C012
CAF"
CER
,01MF
CK058X K
C013
CAP
CER
.01MF
CK05BX K
C014
CAP
CER
.01MF
CK05BX K
C021
CAP
MINI CER
68PF
NPO
63V
C024
CAP
CER
,01MF
CK05BX · K
C025
CAP MINI
CER
120PF
NPO
63V
,
C027
CAP
DIP
TANT
10MF/25V
'
C030
CAP
ELEC 10MFD
25V
NP
V
MT
C035
CAP
VAR
5-55PF
C036
CAP
CER
0.1MF
CK05BX K
C042
CAP
CER
, 01MF Cl<05BX K
C043
CAP
CER
.01MF
CK05BX K
C044
CAP
CER
0.1MF
CK05BX
~~
C045
CAP
CER
0.1MF
C~:.058X K
C046
CAP
CER
•
0012MF
Cl
(
05
C047
CAP
MICA
56
PF
C048•
CAP
CER
0,lMF
CK05BX K
C049
CAP
CER
0,1MF
CK05BX K
C050
CAP
CER
•01MF
C~
::
05BX
~~
C051
CAP
CER
0.
001MF
C~::05
C052
CAP
CER
•01MF
C~
~05BX K
C053
CAP
MINI CER
33PF
NPO
RECT
C054
CAP
MICA
200
PF
C055
CAP
VAR
·
5-55PF
C056
CAF'
CER
0.
!MF
C~
:05BX K
C057
CAP
MICA
1000PF
500V
C058
CAF'
MICA
470F'F
500V
C059
CAF'
CER
0.1MF
CK05BX K
C060
CAF'
CER
0,
001
MF
Ct<0
5
C061
CAP
CER
0.lMF
CK058X K
C062
CAF'
TAN
1MFD
35V
C063
CAP
MINI CER
33PF
NPO
RECT
C064
CAP
CER
0,lMF
CJ<05BX
I<
C065
CAP
CER
0,lMF
CK05BX
K
C066
CAP
CER
•01MF
C~
::
05BX K
C067
CAP
CE:R
0.1MF
CK05BX
K
C068
CAP
CER
470
..
PF
CK05B
C070
CAP
CER
0,
001MF
C~~05
C071
CAP
CER
0,001MF
CK05
C072
CAP
TAN
1MFD
35V
C073
CAP
CER
0,1MF
CK05BX K
QlY,
1
1
1
1
1
1
1
1
1
1
1
1
1
1
1
1
. 1
1
1
1
1
1
1
1
1
1
1
1
1
1
1
1
1
1
1
1
1
1
1
1
1
1
1
1
1
1
PCB
Assy.
6608-3713
Rev.A
1TT
STOCK
NO.
1015-(2)(2)01
1015-0001
1015-0010
1015-0002
1015-0001
1015-0002
1015-0002
HH~-0002
1017-0680
1015-0002
1017-1200
1008-0100
'
1010-0013
1012:-0555
1015-(2)001
I
1015-0002
1015-0002
1015-0001
1015-0001
1015-0040
1001-0560
1015-0001
1015-0001
1015-0002
1015-0010
1015-0002
1017-0
,'330
1001-0201
1012-0555
101~-0001
1001-0102
1001-0471
1015-0001
1015-0010
1015-0001
1008-0011
1017-0330
.
1015-0001
1015-0001
1015-0002
1015-0001
1015-0470
1015-0010
1015-0010
1008-0011
1015-0001
Pago
1
ofS

STEAM POWERED RADIO.COM
Model
8S4
FM
Modulation
and
Stereo Monitor
PCB
Assy,
6608-3713
RF
Preselector Board
Rev,
A
CKT.
REY,
C074
C075
C077
C078
C081
C082
C086
C087
C088
C090
C091
C092
C093
C094
C096
C097
C098
C099
Cl00
Cl01
C102
CR01
CR02
CR03
CR06
FL01
HS01
HS02
J003
J004
J007
J009
J010
J011
L002
L003
L004
L005
L010
LED!
LED6
PCBl
0001
Q006
0007
0008
DESCRIPTION
CAP
CER
820PF
CK0 58X
CAP
CER
0,lMF
CK05BX
K
CAP
DIP
TANT
10MF/25V
CAP
CER
0,lMF
CK058X
K
CAP
CER
0,lMF
CK05BX
K
CAP
CER
0,lMF
CK05BX
K
CAP
CER
0,lMF
CK05BX
K
CAP
CER
0,lMF
CK05BX
K
CAP
CER
0,lMF
CK05BX
K
CAP
MINI
CER
120PF
NPO
63V
CAP
CER
0,1MF
CK05BX
K
CAP
CER
0,lMF
CK05BX
K
CAP
CER
0,lMF
CK05BX
K
CAP
CER
0,1MF
CK05BX
K
CAP
CER
0,1MF
CK05BX K
CAP
ELECT
1,0MFD
50V RADIAL
CAP
ELECT 1,0MFD 50V RADIAL
CAP
ELEC 10MFD 25V
NP
V
MT
CAP
CER
0,lMF
CK05BX K
CAP
CER
0,lMF
CK05BX K
CAP
CER
,01MF CK058X
K
DIO
1N3064
DIODE VERICAP
88505G
2-16PF
DIO
HP5082
HOT
CARRIER
010
1N3064
FILTER
10.7MHZ
IF
TUNER
HEAT
SINK
WAVESOLDERABL.E
HEAT
SINK
WAVESOLDERABLE
CONN·.
12
PIN
HEADER
MALE
,100
CTR
PL
UG
LOCK
,10
CTR
8
PIN
CONN
3PIN
HEADER
MALE
,100
CTR
CONN,
12
PIN
HEADER
MALE
,100
CTR
CONN,
12
PIN
HEADER
MALE
,100
CTR
CONN
W/0
LOCK
,100
CNTR
3
PIN
INDUCTOR
1'00UH
INDUCTOR
100UH
CHOKE
RF
2,2UH
CHOKE
RF
2,2UH
CHOKE
47UH
LED
GREEN
LEDCO
8"
LED
HP
5082-4487
CLEAR
PCB
RF
PRESELECTOR
BO
TRANS
2N3563
TRANS
2N3563
TRANS
2N3563
TRANS
2N3563
Qn',
1
1
1
1
1
1
1
1
1
1
1
1
1
1
1
1
· 1
1
1
1
1
l
1
1
l
1
1
1
1
1
1
1
l
1
1
l
l
1
1
1
1
1
1
1
1
1
TfT
STOCK
NO,
1015-0820
1015-0001
1008-0100
101~-0001
1(1H3-0001
1015-0001
1015-0001
101!\-0001
101~-0001
1017-1200
101,-0001
1015-0001
,
1015-0001
1013-0001
I
1015-0001
1010-0009
1010-0009
1010-0013
101~-0001
101~-0001
1015-0002
1281-3064
1290-010~
1282-2800
1281-3064
1052-0110
2010-0637
2010-0637
2250-5842
2250-9508
.
2250-5830
2250-5842
2250-5842
2250-5803
1531-0101
1531-0101
1~31-0021
1531-0021
1~31-0470
128~-49~1
1285-4487
1600-3672
1271-3e.63
1271-3~63
1271-3563
1271-3563
\
Page
2ofS

STEAM POWERED RADIO.COM
l.
l.
I.
Model
8S4
FM
Modulation and Stereo Monitor
RF
Presel~torBoard
CKT,
REF.
DESCRIPTION
Q009
TRANS
2N3563
0011
TRANS
PN2222A N
PN
R002
RES
CAR
FILM 1/4W
51/.
101<'.
R005
RES
CAR
FILM 4.71< 1/
4W
51/.
R006
RES
CAR
FILM
1/4W 5
'l.
150
OHM
R007
RES
CAR
FILM
1/
4W
5'1/.
10
~:
R008
RES
CAR
FILM
4.7K
1/4W
51/.
R011
RES
CAR
FILM
1/4W
51/.
2,2K
R012
RES
CAR
FILM 1/4W
5'1/.
470
OHM
R013
RES
CAR
FILM
l/4W
51/.
·
470
OHM
R014
RES
CAR
FILM 1/4W
5'1/.
10K
R015
RES
CAR
COMP
1/4W 5¼
330
R020
RES
CAR
COMP
1/4W
51/.
680
R022
RES
CAR
FILM 1/4W
51/.
1K
R026 .
RES
CAR
FILM 1/4W
51/.
10
OHM
R031
RES
HT
FLM
1/8W
1¾
1K
R035
RES
CAR
FILM
4,7K
l/4W
5¼
R036
RES
CAR
FILM 1/
4W
51/.
15K
R042
RES
CAR
COMP
1/
4W
5
1/.
100~:
R043
RES
VAR
PC
MT
5K
1T
R044
RES
VAR
PC
MT
~K
1T
R045
RES
CAR
FILM 1/4W
51/.
390
OHM
R046
RES
CAR
COMP
1/4W
51/.
22K
R051
RES
CAR
FILM 1/4W
51/.
47
OHM
R052
RES
CAR
FILM· 1/
4W
51/.·
47K
R053
RES
CAR
FILM 1/4W
51/.
10~:
R054
RES
CAR
COMF'
1/4W
51/.
100K
R05~
RES
CAR
FILM 1/4W
51/.
151
<
R056
RES
CAR
FILM
l/4W
5
1/.
10~:
R057
RES
CAR
FILM
4.7K
1/4W
51/.
R058
RES
CAR
FILM 1/
4W
51/,
2,
21<
R059
RES
CAR
COMP
1/
4W
51/.
100~:
R060
RES
CAR
COMF'
1/
4W
5
1/.
100
R061
RES
CAR
FILM
1/
4W
51/.
10~:
R062
RES
CAR
FILM
4.7K
1/4W
51/.
R'2l63
RES
CAR
COMP
1/4W
51/.
270
R064
RES
CAR
COMP
l/4W
51/.
6,8K
R06~
RES
CAR
COMP
1/4W
51/.
1.5K
R066
RES
CAR
1/4W
51/.
200K
R067
RES
CAR
FILM 1/4W.
51/.
27K
R068
RES
CAR
COMP
1/4W
51/.
1.2K
R069
RES
CAR
COMP
1/4W
5'1/.
240
R070
RES
CAR
COMP
1/4W
51/.
.
100
R071
RES
CAR
FILM
1/4W
5
'1/.
lK
R072
RES
CAR
FILM 1/4W
51/.
10
OHM
R073
RES
CAR
FILM 1/4W
51/.
1K
PCB
Assy.
61
. \
Rev.A
QlY.
nTSTOCK
NO,
1
1271-356
-1
1
1271-2223
1
1065-1002
1
10~5-4701
1
1065-0150
1
1065-1002
1
1065-4701
1
1065-2201
1
106~-0470
1
106~-0470
1
1065-1002
1
1065-0330
'
1
1065-0680
1
1065-1001
I
1
1.065-0010
1
1061-1001
. 1
1065-4701
1
1065-1502
1
1065-1003
"1
1072-5001
1
1072-5001
1
1065-0390
1
1065-2202
1
1065-0047
1
1065-4702
1
1065-1002
1
1065-1003
1
1065-1502
1
1065-1002
1
1065-4701
1
1065-2201
:
1
106~-1003
1
1065-0100
1
1065-1002
1
1065-4701
1
1065-0270
l
1065-6801
1
'
1065-1501
1
1065-2003
1
1065-2702
1
1065-1201
1
1065-0240
1
1065-0100
1
1065-1001
1
1065-0010
1
1065-1001
Page3
of
S