Rohde & Schwarz 802.2020.52 User manual

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I,
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VOLUME 1
.
rVI
RADI C
TESTER
C T
802.2020.
802.2020.54
u I
&SCHWARZ
Measo\~i~\:~i Instruments
and Syst~s Division
UNIC TIN
The service manual consists 2 volumes
Printed in the Federal
Republic
of Germany
802.2020.52
22

I J
Contents CMT
1. Data eet
2. Pr
t
ration
3. Maintenance
Be ce
Volum.e 1
4. rvice Manual for Complete Instrument
5. rvice Instruction for Modules
Power Pack 80 I» {\\ 0 (! €i (I,'j €I "" ¢ (,i $ $ 0 • @ $ GO-Ill {)I f$ QI 0 @ @
Dig i t al Un i. t 0 e!: Q e G @ ® 4\1 I» @ e a 8 61 '" @ e '* Ii' (I) $ €I GI (1) 1$
Analog Unit .•••••••.••.•••••••.•.•••••
1st Modulation Generator Module ••••.•
RF Oscillator Module including •..•• J
Reference Oscillator (OCXO) CMT-B1 __
Output Stage ••••••••••••••.•••••.••••
Attenuation Set Module ••••••• ~ •••••••
Volum.e 2
5. Service Instruction
r Modules
Osc illoscope Module .•••••••••••••••..
Display/Keyboard Module .••••••••••••.
Adjacent-channel Power Meter CMT-B6 •.
2nd AF Synthesizer CMT-B7 •.•••••.•••.
lEC Bus/Control Interface CM-B4 ••••••
Autorun Control/Printer Interf. CM-B5
RF Millivoltmeter CM-B8 ••.•.••..•• $ ••
Duplex Modulation Meter CM-B9 •.••.•••
DTMF Decoder CM-Bll •••••••••••••••••.
Transfer Memory Mod e CM-Z1 •••••••••
Order No.
802.2814.02
802.4517.02
802.8435.02
[email protected]
802.8835.02
803.8916,,02
802.7616.02
802.4223.02
803.111LOO
802.3662.00
803.7810.02
803.2618.02
803.3914.02
803.3314.02
803.6813.02
803.5317.02
803.4610.02
803.7510.02
Index
E} III & Q fb 6
7
8

4. • 1
4.. 1 1
4. 1 .2
4.. 1 • 3
4.. 1 • 4
4. 1 .5
4.1.6
4.1.8
4. 1 .9
4.1.10
4.2
4..2. 1
4.2.2
4.2.3
4.2.4
4.2.5
4.2.6
4.2.7
4.3
4.3.1.1
4.3.1.2
4.3.2
4.3.3
4.3.3.1
4.3.3.2
4.3.4
4.3.4.1
4.3.4.2
4.3.5
4.3.5.1
4.3.5.2
4.3.5.3
4.3.5.4
4.3.5.5
4.3.5.6
4.3.5.7
4.3.5.8
4.3.5.9
4.3.5.10
4.3.5.11
4.3.6
4.3.7
4.3.7.1
4.3.8
Contents
$ ~ $ ~ e ¢ ~ @ $ ~ ~ & ~ ~ ~ ~ ~ ~ ~ ~
RF sizer ""f;"'@{jf;liltltl,;e>@I$!t<Q~1lI ~e0 4Jw@@0(fl0B$
tput Stage e (II ~ ¢; e €5 e Ii> $ @ ® '" $ .... I/il (!> ~ ~ <t! (') @ ~ _@ (J €I
1 st Modulat Generator. • . • . • . .. •. 0..... .
An Uni t (;j @ III Ill< ® <!J 0 0 @ It @ 0 0 "" e ~ {!l ~ ttl e ® ~ tl e & I:'il e $ e Q III @ @ Gio
Di,git Unit e III (/I &- $ ¢ @ @ ~ e- G (I 0 G- @ $ ($ tl!I @ (!I (j 0> €I ~ $- @ @ e (f! IJ! €I 6!J $
Po we r Pa @ @ " G @ e (l i!/I €> @ $ Q «> Ii'> $ ® @ @ o@ e ® Gee e 0$ 6 0 E! to <!!> ~ ~ '" e,
Front Panel
Oscillo
.
l..ons f> 0 4.' e 0 tI:> @ e Ii? Q 0 0 1% $ ¢ ~ If; @ 0 $ (1) 0 $ @ ® 6 Il> @ ¢ @ @> 0 III @ (!J
Mechanic
Opening the Instrument .••.•••••..••••••.••.••
Removing Plug-in Modules ...••••.•....••.•...
Removing the Power Pack ••.••..•.•....•.•....•
Removing the lEC Bus/Control Interface Option
CM-B4 and the Autorun Control inter
In terf ace Opt ion CM-B 5 •••••••••••••••.•••.•.•
Removing the Attenuation Set •.......•....•.•.
Removing the Oscilloscope ..•......•.........•
Removing the Front Panel ••..•........•.••.•..
Page
4.1
4.. 1
4. 1
4.1
4. 1
4.2
4.3
4.3
4.3
4.4
4.4
4.4
4.5
4.5
4.5
4.5
4.6
4.6
4.6
4.6
Testing and Adjustment .••••••......••...•... 4.9
A.djusting the Power Pack ..•...•....•......... 4.9
V Operating Voltage •..•..•...... ' •.......•. 4.9
4 V Operating Voltage •....•............••.. 4.9
Adjusting the Digital Unit .•........•.....•. 4.10
Adjusting the RF Oscillator ••......•.••..•.. 4.10
Frequency Adjustment •••.••...••...•...•...•. 4.10
Level Adjustment •..•.. 0 ••••••••••••••••••••• 4.10
Adj ust ing the Output Stage .••.•.....•.•••.•. 4. 11
Level Adjustments ••.••.•••..•.•.....•.•..... 4. 11
Adjusting the Modulation Depth •.•..... ~ .•... 4.11
Adjusting the Analog Unit ..•.••.......•..... 4.11
Adjusting the LO Conditioning ••..•..•.•..••. 4.12
Adjusting the RF Amplifier, FM ........•..••. 4.12
Adjusting the RF Amplifier, AM •••••••••••••• 4.12
Adjusting the FM Demodulator ••.•••..•.•.•... 4.12
Adjusting the AM Demodulator •••......•...•.. 4.13
Adjusting the CCITT Filter ..••...••......... 4.13
Adjusting the Distortion Control ....•.•.•••. 4.14
Adjusting the 1-kHz Notch Filter .....•..••.. 4.14
Adjusting the 990-Hz Notch F ter •.•••..••.. 4.14
Adjusting the 1010-Hz Notch Filter ....•..... 4.15
Adjusting the Power Display ••..•.....•..•..• 4.15
Adjusting the At tenuation Set ......•......•. 4. 15
Adjusting the Oscilloscope ••....•...•...•.•. 4.15
Adjusting the Horizontal Beam De ection •... 4.16
Opt ion S III t:I $ III III '" @ r.1 @ ~ €I @ @ @ @l I!}} ~ (II e @ ~ @ II) (> $ eo", (i 0 0 ((I IllI 9 @ @ oIj; 4 (!J 16
4.4 Troubleshooting .••.••••.....•.•..••.•.•.•... 4.17
802.2020.52 9 E-2

Contents
5
Service Manual for the Indi
Pa,
Un
Unit
1st Modulation
RIr Oscillator
Output Stage
Attenuation
Generator Modu ...... .
e, inc1- Reference Oscillator CMT-B 1
.. e
10
ex
1
2
3
4
5
6
7
E-1

Gener
Serial data transmission
pi ace on three 1 ines:
re us an extern
just or test
ual pl ug-in modul es t s
STROBE. e ta must be
p in to
e ic strument.
e t i
di ram
data transmiss is shown
ow.
STROBE
The data on the DATA line are ansferred to the parallel/seri
converter with each rising edge of the CLOCK pulses; a subsequent
STROBE pulse enables the data at the converter outputse The fol-
lowing BASIC program shows how the user port the PUC can
dress the module:
10 POKE 59259,255
20 OIM A(20)
30 A(1)=O:A(2)=1 ••.
40 FOR lT020
50 POKE 59471,A(I}
60 POKE 59471,A(I)+2
70 NEXT
80 POKE 59471,4
90 POKE 59471,O:END
Set user port
Number of individual data bits,
20 in this case
Define individual data
Read in data;
Line with significance 2° = DATA,
significance 21 = CLOCK
Output STROBE pu~se on line
with significance 2
41

1
wi modulation generates
from 500 to 1000 MHz which is
ies
three sel
oscillators~ Three phase
by
loops
setting@
ut
(PLL)
The rna a 1
O~MHz
to whi
t oscillator
(
oscillator
e-
s :Ui as
1 inked @ The 10
reference equency
justed ±2 kHz and whose
is re ence frequency
tors.
100-MHz
is
a cryst
ncy,
for the coarse
ram uces
which can be ad-
ed by a tor of 100,
PLL of the RF oscilla-
If the Duplex Modulation Meter option CM-B9 not fitted, the RF
synthesizer is operated as a generator in the receiver test and
as a m ing oscillator in the transmitter test. Information on
voltages and on the locking of the PLLs is ssed to the control-
ler via the analog unit test purposes and trouble-
shooting.
The output stage divides the frequencies provided by the RF syn-
thesizer such that a frequency range 31.25 to 1000 MHz is co-
vered. Appropriate filters are connected in series with the fre-
quency div iders to ensure that the harmonics ratio required is
attained. Frequencies <31.25 MHz are generated by mixing the
100-MHz crystal frequency wi th a corresponding oscillator fre-
quency.
A controlled amplifier increases the RF signal to the max. el
of 13 dBm. Fine variation of the level is achieved by mod ifying
the re input for the control via D/A converters. Amplitude
modulation is also active and the modulation signal is superim-
po on the reference value the O/A converter.
The AF synthesizer and the modulation con ler are accommodated
on the 1st modulation generator module. The AF synthesizer is
sically a set of shi registers whose outputs are activated in
succession by a clock generated by the controller.
802.2020.52
tL 1 B-1

The output levels are added by a resistor chain to give a sine
curve. The stepped sinewave produced is freed from harmonics by
sui table fil ters and output following an attenuation set con-
sisting of D/A converters and selectable voltage attenuators.
l,ng to
ler
AM
ides level provid modu-
FM paths. converters are u to
n. 4>M is en-
The an og unit consists of llowi funct uni ts: RF am-
plifier, LO conditioning, demodulators, AF condition and DC
amplifier.
The RF signals to be measured are regulated to a constant level
in the RF amplifier according to the type of modulation and then
routed to the RF frequency counter and the mixer.
The LO conditioning amplifies the signals from the output stage
to the level required for the mixer. Frequencies below 31.25 MHz
are divided to generate the IF of 455 kHz for signal frequencies
up to approx. 1 MHz. A generator with amplitude modulation is in-
tegrated self-testing.
The demodulators contain the IF amplifiers, the AM and FM/<llM de--
modulators and filters required to suppress the IF.
The AF conditioning weights the demodulated signal and the signal
from the AF VOLTM input according to the measuring requirements;
various filters (300-Hz HP, CCITT filter, 150-Hz HP) can be con-
nected as required (rms or peak values). The signal to be mea-
sured is regulated to a constant rms value for distortion mea-
surements and subsequen freed from the wanted signal in a
notch filter.
The rectifiers (peak v ue and rms value rectifiers) are conta
ed in the DC amplifier. A DC multiplexer connects the voltages
supplied by the other modules to a selectable DC amplifier which
passes the signal to the A/C converter incorporated in the digi-
tal unit.
802.2020.52
4.2

The digit unit consists of the lowing function units:
RF counter, AF counter, AID converter and controller.
The RF counter counts the
r 1 to 1 000 MHz
to generate LO
from
AF counter counts
well as sign s in
put AF VOLTM.
ler s
idu modules are
STROBE). Power fa I
of
a s
Hz appl i
ete instrument.
I data
via. seri
data I s
th
an
it
al bat
n
to
to
(i
DATA,
t e
when
ensures at data are
o
not
lost power
failure
instrument is
as
in-
the
p
or
The power pack supplies the strument with the operating vol-
tages of +5 V, +12 V, +15 V, -15 V and +24 V. The voltages are
generat using a switched-mode power supply so that the instru-
ment can also be operated using standard car bat ies. When con-
nected to the AC power supply (I a transformer reduces the line
voltage to the voltage requi for the switched-mode power
supply.
The instrument operates in STANDBY mode if the power pack is
switched off from the front panel; all voltages are then switched
off except the +12 V supply which is used the 10-MHz crystal
oven and the STANDBY logic.
Fuses are provided on the input side to protect the power pack.
STANDBY mode is automatically switched on if one or more voltages
on the secondary side are short-circui ted wi th each other or to
ground or if the power pack is operated without a secondary load.
All keys required to operate the instrument as well as the loud-
speaker potentiometer and the spin whe for fast adjustment of
the parameters are locat on the front panel.
The set parameters and the resul ts are output on LCDs connected
to the front panel via conductive rubber contacts. The loud-
speaker amplifier is also mounted on the panel wi th the
loud aker control. A ribbon cable connects the front panel
units to the motherbo and the digital unit.
802.2020 52
4.3 E-1

The attenuation set contains the at
for attenuating the RF synthesizer I
ators in which the major part of the
into heat. The connection between
attenuators is via a 50-~
power d , an unit
rear p are connected.
ing RE' d
set during mechan
scre onto the attenuation set
uates the voltages the
via a ribbon c e.
uator connected to relays
as well as power attenu-
applied power is converted
power attenuators and the
star arr ement to which
RF-30 0 i on
to tect the attenuation
to tect power. A B
s the attenuat set
The is connec to
The oscil scope enables visu display of the demodulated s
nals, the beat signal and externally applied signals.
The voltages required for the oscil scope tube, the blanking am-
plifier and the de ection amplif are generated by a switched~
mode power pack with an operating voltage of 24 V. The deflection
coefficient.s and the operating mode are read from the digital
unit into RAMs, read out by D/A converters and writt.en as ssa-
jous figures on the screen in the form of numbers, let.t.ers and
arrows. The oscilloscope is powered via ribbon cables which are
routed to t.he front. panel.
The function descriptions of the options are contained in the re-
spective service manuals (Section 5).
802.2020.52
4.4
E-1

Exce the front panel,
cil scope, the CMT modules
pairs can therefore be carr!
be comple y replaced~
power pack, at tenuat set and os-
are designed as pl ug-in cards. Re-
out rapidly or the faul c can
e
ectr ic connections are
common mothe
Loosen the
feet (marked
t. Remove
the reare
s are rout
es.
coaxi
p e
via
es. The au: 1S
own out via
Phill ips screws the rear used to secure the
A in Fig. 4-1); the capt screws remain in the
the feet and slide out the top and bottom panels to
Caution: The power plug must be disconnected before removing the
modules.
These modules are secured by two rails at the sides next to the
motherboard. Loosen the Phillips screws marked A in g. 2 and
press towa~ds the rear using a suitable tool inserted into
bracket B. Disconnect any coaxial and ribbon cables present and
remove the modules from the instrument.
Note:
If the IEC Bus/Control Interface option CM-54 and the
Autorun Control/Printer Interface option CM-BS are pre-
sent, these must be removed before removing the digit
unit module (see Section 4.2.4).
Disconnect plugs X60, X61 and X70 from the motherboard. Loosen
the five Phillips screws marked C and D in g. 4-1 and remove
the power pack from the arne. Ensure that the cables leading
from the power pack are not subjected to stress which could break
the conne lead- ugh f ters.
802.2020.52

Loosen the Ph lips screws on the rear of the instrument (marked
D and E in Fig. 1) and remove the option( s) towards the rear
multi e connectors of the digital unit.
Unscrew two SMA
j t and pull off
connectors
two coaxi
from c
connectors.
es with
a
id
e
by
Fig.
at tenuat se t th the heat si
which are fi
screws and remove
is mounted to assis
ur screws, two
2). Loosen
at s
drive is fitted on
screws. Be removing the board,
overtemperature sensor.
wi nuts (marked C in
attenuat set th
attenuat
solder
set using six
two wires to the
Note:
The attenuation set must not be opened; the internal com-
ponents consist of thin-film substrates which can only be
replaced in the factory.
Loosen the hexagon socket screws of the rotary knobs on t
panel and remove the knobs. Loosen the six screws with which the
inscription panel is secured (two screws in the centre between
the displays). Loosen the screws marked A in Fig. 4-3. Disconnect
the two ribbon cable pI ugs and the coaxial connector X605 from
the analog unit module. The oscilloscope assembly can now be re-
moved from the front.
Remove the inscription panel as described in Sect 4.2.6 and
loosen the screws marked B in Fig. 4 • Disconnect the three rib-
bon cable connectors and remove the panel.
4 6

Figs. 4-1 to 4-3 show the screws to be loosened to remove the
modules.
Fig. 4-1
A
(
B
c
Fig. 4-2
802.2020.52
4 7

A
B
Fig. 3
802.2020.52
B
B B
4.8

Exact testing
out according to
the manual re
re necess
the instrument specificat should carried
Section 3.2 in the Operating Manual. Each test
s to a ssible justment. Renewed testing is
low ng justments.
1
carr
or :If
out
justments on
e,
y i
c
justments, ensure
to i unin
ues can e measurement errors.
es uld ser
out. If a module must
a fundament unit
justment as scr
outs
(e.gw d
Sect 5.
us
justment is
instruments
uni t), c
e
modules
if this
viously
of justments module to module and also with:ln
ensures that the adjustments do not fect one another;
is nevertheless possible, re rence is made to the pre-
required setting.
~ Switch on instrument
Adjustment po
: ~ X61 on motherboard
Adjustment value: ~ Adjust to 5.3 V ±10 rnV using R12
Setting: ~ Switch on instrument
Adjustment
int: ~ X61 on motherboard
Adjustment value: ~ Adjust to 24 V +100 rnV/-O mV us
R56
802.2020 52 4.9

Setting:: + Switch on instrument
ustment
: + X58/A21 on
ustment just to 10 V ±1 mV usi
09
lout mod e connect to
e
usi
n
Settings:
Adjustment
Adjustment
Settings:
Adjustment
e.
+ Receiver test
+ Frequencies
as
in following
table:
Frequency
Trimmer
500.001 MHz
C21
655.001 MHz
C51
825.001 MHz
C81
point:
+
X9/2
value:
"",' Adj ust
to 2.5
V
DC
±100
mV using
C81
+ Receiver test
+ Frequencies as in following table:
F'requency
575 MHz
730 MHz
900 MHz
int: + X310
Trimmer
R49
R79
R109
er e.
1 p 1,
ustment
: + Adjust to 0 dBro ±3 dB using R49, R79, R109
802.2020.52
E-2

Note:
Check
stage.
justment 4.3.3.2 before adjusting the output
Remove e
connect usi
c e.
j ustment: $
e
+
'Ie
1
Fre- Level Tr
justment
ue
mer
100 MHz
+13 dBm
14 13 dBm ±O.OS
dB
*:
1,00 MHz
-16.9
dBm R4S2
.9 dBm
± 0.05
7.9
MHz
+13
dBm R641 13
dBm ±O.OS
dB
'Ie
7.9 MHz
-16.9 dBm
R663 .9 dBm
±0.05
dB
ustment point: + X401 or RF IN/OUT on the front panel
Compare 1
using RS14.
of 13 dBm at 1 GHz and 330 MHz and t
average
+ Rece test
+ Frequency 100 MHz
+ Level 0.1 dBm
+ Modulation 80% AM
+ .AF =: 1 kHz
ustment point: + X401 or RF IN/OUT on the front 1
Mj
value: + Adjust to 80% AM ±0.1% AM using R503
+ Remove the module
cables .
.,. Open module.
802.2020.52
the CMT and connect us ing the
4. 11
apter
E-1

ings:: + Transmitter test
+ Fixed equency 15 MHz
ustment
:: + D100/3
ustment
us
02
TTL lev esent at,
:: + Transmitter test
+ Apply 500 MHz, 20 mV to
+ at: FM
:: + X610/50 n
Adjustment value: -1" Adjust to 150 mV ±5 mV using 7
Note: The adjustment 4&[email protected] must be checked before this adjust=
mente
+ Transmitter test
+ Apply 500 MHz p 20 mV t.o INPUT2
+ Demodulation: AM
Adjustment point: + X610/50 n
Adjustment value: + Adjust to 75 mV ±5 mV using RSS
4 .. 3 .. 5 .. 4
G
.,
Adjusting the PM Demodulator
+ Transmitter test
+ Apply 100 MHz f 20 mV, 10kHz deviat
INPUT2
+ Demodulation: FM, ± PK
2"'
Adjustment point: + DEMODULATION display
Adjustment value: + Adjust to 10 kHz± 10Hz using R304
to
-). Adjust to 0 VDC ±5 mV at DEMOD connector
using R213
802.20 .52 E-1

The fol-
Note: Check adjustment 4.3.5.4 be
lowing three adjustments mutually
just in the ifi and
one ad-
ain at the
tter test 100 MHz
MHz, 10 mV % AMF AI"
: AM f ±
1: "'" 8 1
1: "'" just to 250 mV ± 2 mV us R1
(t se t account
ustment
2: "'" DEMOD connector
Adjustment value 2: "'" Adjust to minimum limitation
half-wave using R254
r sine
Adjustment pOint 3: "",DEMODULATION display
Adjustment
Settings::
Adjustment point:
Adjustment value:
Check:
Note:
802.2020.52
3: "'" Adjust to 80% ±O.1% using R275
(take settling time into account)
"'"
Receiver test
"'"
Apply
1 V
rmsp
800 Hz to AI" VOLTM
"'"
Press CCITT
"'"
AF VOLTMETER
displ
...
Adjust to
1 V flO mV using
R388
"'"
When
pressing
CCITT ain
(off) f
the
play must not
change.
"'" The rms meter should be
to this j ustment.
ibrated
4.13
dis-

Note: The lowing two adjustments mutually affect one another.
Check the adjustments at the end and correct if necessary.
Adjust:m.ent
j ue
Settings:
Adjust:m.ent point:
Adjust:m.ent value:
Settings:
Adjust:m.ent point:
Adjust:m.ent value:
test
1
to AF V01,TM.
1:; + 1
1: + Adjust to 1 V
rms
±1 mV us
43
+ N450/1
just to s 2
usi
42
+ Receiver test
""'" Apply 1 kHz, 1 V
rms
with low distortion
<'0.01%) to AF VOLTM
+ Press DIST
+ AF VOLTMETER display
+ AI ternately adjust to minimum distortion
«(O~3%) using R557 and R556
+ Receiver test
+ Apply 1 V
rms
, 990 Hz with low dis-
tortion (~0.01%) to AF VOLTM
+ Press DrST
+ AF VOLTMETER display
+ Adjust to minimum distortion (~O.3%)
using R566
4.14
E-1

+ Rece st
+ Apply 1 V
rmsf
1010 Hz with low
distort,ion ((0.01%) to AF VOLTM
+ Press DIST
ustment
:: + AF
di
+ ust to minimum di t
(( 0 •3 %) us 71
+ Transmitter test
+ a f
::::; 10 W to
OU'1'
point:: + RF POWER di
ay
Adjustment value: + Adjust to 10.2 W using R672
Settings: + Receiver test
+ Frequency 100 MHz
+ Level 13 dBm
ustment point: + RF LEVEL display
Adjustment value: + Rotate R34 until the attenuation set is
heard to switch and -47 dBm is output on the
display; subsequently r~tate R34 approx. 1/6
revolution backwards '
Note: Check the switchover eshold from receiver test to
transmitter test llowing adjustment. The switchover
shold is at 0.35 W, approx. If the threshold is too
low, rotate resistor R34 back further.
The oscilloscope must first be removed (see Section 4.2.6) and
connected using the adapter cable; remove the mu-metal screening
of the tube.
Note:
When adjusting f ensure that no high-vol tage parts are
touched.
802.2020.5
4.15