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INSTRUCTION MANUAL
Tmktmnix, Inc.
R.O. Box 500
gemrenon. Oregon 97005
WARRANTY
All 'rEKTRONI>: imhrrnm ~ P are waI*ranted asai nst
I
r
def eeltive materialm and workrnunship for one year. Pbny
question$ with respect t o the u uld be taken UP
. .
with your T f KTAONIX FieW Enginmr o representat!
r
All r quests for 1
c PI-rn 1
...
in youl .-.
.15m.
T*
.,,is will - .-..
directed to the TE.KTRONIX f'iekl Office c
,
BSSU~G - K..
UIm YV-I
w e. Please include the innrurnent Tvpe Number or P
b
~ u m t and Seria11 Number w
ler lue
W I G 11.
ficationsand p i c e change privileges re!
Copy1 .ight 0
1973 by Taktmrrix, Ine.. Bet on.
Printed in the United Smes of America. All rights mwrved .
Conte,nts of this publication mav not be r q InY
form ,without pelntision of Telctronix, lnc.
..and Foreig~ IS.
." . .
'RONIX is a registered t Tekmnix. Ine.
TABLE OF CONTENTS
SPECIFICATIONS
lntmdudion
Electrical C W m % e d i
OPERATlNG INSTRUCTIONS
IntnxIuFtion
Function d C s Front R s Cartmls dCMmeeton
nl
Gmeral Oparating Informadon
Applicaolont
SECTION 3 PERFORMANCE CHECK
Inirduetion
opamtioml c h d
Perfwmanee Verification of Specified F h d r t i a
Equipmatt R e q u i d
Ch& c k i b r a t w Fraqunnq awl Output
Check Frequency Ran* and Display Flatn6n
Check lntwmdulation Distwrion
SECTION 4 SERVICE INSTRUCTIONS
Imdmion
Cirmit Doadption
Cslibratlon
fdnintmmm
Preventive-
.conective
Obtaining Replwmmt Para
Soldering Technique
Replacing h m M i w and bmporwW
\
SECTION 5 OPTIONS AND MODLFlCATlONS LJ
SECTION 6 ELECTRICAL PARTS LIST
SECTION 7 DIAGRAMS
SECTIOM 8 MECHANFCAL PARTS LIST AND ACCESSORIES
CHANGE INFORMATION
Fig. 1.1. 7 K l f CATV Pmmpllfmr.
Q
SPECIFICATIONS
Introduction
The fK11 Preamplifier is a 7000Ssries Plug-InUnit that
This manual contains information relative to the owr- i s designed t o operate asan accsssory for the 7L12 or 7L13
ation and m i c e of the 7 K l t CATV preamplifier. The Spectrum Analyzers. This unit. in wmbinatlen with a
manual is divided into sections with epproprlate titles. The spectrum analyzer, will measure CATV system performance
Table of Contents that precedes this section giver a as required by the FCC and mrnpare system performance
breakdown of each section. to industry nandards.
ELECTRICAL CHARACTERISTICS
(Indudesthe7L12or 7L13)
Frequency Range 30 MHz t o 890 MHz.
Display Flatness (7K11/7L12 or 7 K l f n L 1 3 ) *1rll dB, with respect to 50 MHz level, over the frequency range of
M MHz to 300 MHz, increasing to *2 dB with respect to 50 MHz,
wer the full frequency range.
Sensitivity (Signal + noise = 2X noise, LIN mode) The following characteriptics apply at 50 MHz in combination with
the 7L12 or 7L13 Spectrum Analyzer.
Signal Level Reduaion
Bandwidth
.,- Noise figure for the 7K11 is 5 dB or less.
IM products from two 0 dBmV input aignah within any frequew
span are down 80 dB or more. The 7K11 h not degrade the IM
i
l
l
distortion characteristicsof the Spectrum Analyzer.
Refwrwnm Level Glibrated levels in 1 dB steps from +79 dBmV to 0 dBmV.
Accuracy is referenced t o the +30d&mV Calibrator at 50 MHz.
+ Max~mum dwiatlon from thls reference IS: 0.2 dBmV + 0.01 d0mV
per dB deviation from the +30 dBmV, 7 K l l reference level. This IS
equivalent to:
- -
k 1 . dBmV + 0.01 1 7 K l t REF LVL 30 dBmVl].
02
Calibrator 50 MHz *0.01% with an abxllute ampZitude lwel of +?AdBmV
W.5 dB, from 75 a, t 2 5 " ~ .
a
. , The input impedance of the 7K11 is approximately 75 R,with a VSWR of 2:l or better with 10 dB or more menuation
Ifrom 50 MHz ta 300 MHz).
C
OPERATION
Introduction and span mtibration. T h e pilot or fundamental 50 MHz
provides the amplitude REFERENCE LEVEL. MOTE:
Thh section desaribea ths function of the from panel Almvs use the 75 R, 5 112 inch cable, which is supplied
mntrols and mnnectore, a general operating womdure and with the aocaswries, to m n w the CAL OUT to the RF
wme applications1 for the mstrument. Performing the INPUT.
operating procedure should help acquaint you with the
7K11 as an actmsory for the Spechum Analyzers in CATV
applications.
GENERAL OPE'RATIMG INFORMATIOH'
FUNCTION OF THE FRONT PANEL
COMTROLS AM0 CONNECTORS This portion of t h e section d s s c r i k the front panel
adjustment procedure necessaw to calibrate the 7 K l l .
REFERENCE LEVEL and MAXIMUM INPUT Spectrum Analyzer, m d 7000Series mainframe a
LEVEL system.
Conmnwic mntrols that s l e n a calibrated reference
level for the top of the graicule on the CRT display. This
level Ean be selected in 1 dBmV or l0dBmV st- to
NOTE
478dBmV. The ~eferenm level is indicated via a readout
w~ndowon the selectors and in the upper left section of the
Exwnel gratkules are design& ao they compensate
CRT display when the 7 K l l is u d with a 7000-Ser~es
for pere//8~of the winera. Grnticvle msakings wlll
oscilloscow that has the redoul feature. This REFER-
therefore be m t an photwpphed displBys.
ENCE LEVEL is also t h e MAXlMUM INPUT signal level
for linear m a t i o n . Amracy i s refereneed to the
+30 dBmV Calibrator at 50 MHz. 1 Reliminsry Setup and Callbratlon P-um
.
a. Plug the 7K11 and Spectrum Anslyzer into a
RF INPUT Connector 7000Ssries mainframe. An oscilloocoDe with variable per-
A 75 BNC i n ~ connemr for the input signal
t sistence or biatable storage is rewmmendd.
BwliCBtion.
b Conned tRe 7K11 and Spectrum Analyzer as shown
.
in Fig. 2-1 and turn the ~ w eon.
r
RF OUTPUT Conmctor
.- A 50 Q signal soum of t h e signel that is applied to the
RF INPUT. This signal level depends on the setting of the c. SBt the controls a d setectdrs as shown in the
REFERENCE LEVEL selector and applied signal lever. The of
illustration. Connect the CAL OUT-~ignal the 7K11 to
t h e RF INPUT and the RF OUTPUT m the Spxtrum
- output is -30 d0m when the input signal levsl quals thm
indreatd by the REFERENCE LEVEL rwdout. NOTE: Analyzer R F Input. Ensure that the Speetrum Analyzer
The JL12 or 7L13 Reference Level can be set to a m i n g Reference k e l Fs set at - i dBm and the 7 K l l
X
such as 4 0 dBm, t o increme sensitivity, provided the REFERENCE LEVEL i s +30 d0mV.
L- additional level (in this mse 10 dB) is summed with the
7Klt REFERENCE LEVEL indimt~on.
d Allow approximately 30 to 40 minutes for the
.
instruments t o stabilize.
+ CAL OUT Connector
Provides access to an accurate +30 dBmV, 50 MHz
- signal, from a 75 Sl soure. This signal i s u M as an absolute
reference for the display a d IS used t o calrbrate the
7 K l l l S p m r u m Analyzer enmble. Harmonicp of the 50
mix M u n , "'mb n 4 No. A
rns 7 K l l -rl.rl:TalrtmnEl
CATV s-r,
. - 1-td
brochum. '.8prtrum And*
NO. A-2515: and ~ m k m i - m m t
Mint, '5pmrurn Anslyw Memuranant Thmw and P-
x -t
r,
wim
md
MHz pilot signal provide a picket fencer of markers across Pen No. 062.733400: em raemmsndsd m r w an awl~catiam
the frequmcy span, which are u d for acwrats frequency md -nmmt svaluttion.
L
REFERENCE LEVEL
IIRPU? AnenuanianJ:
TIMEIOIY: SPECTRUM
+M dRmV
DISPLAY MODE:
C o n W CAL OUT to
RF INPUT 15-112 inch
csblrnl
RESOLUTION: 3 MHz
1
Fig. 2-t. Initid ratup.*howlw wnwol andsslecmr pmitiora
I
@
e. Adjust the oscilloscope Intensity, Focus a n d Astig- c Adjllrt t h R ~ m l u t i n n d mrmp rpPCI for a flirkcr-
. ~ a
metism mntrols for optimum display definition w i t h free display w i t h distiner video and sourd ~ a r r i w .Adiust
normal intensity. t h e sweep speed s the video information mov- mess the
o
d~splay and does not obscure any 'IM b a t ) prducts.
%itch in frlters, adjust Resolution. wrsinence, and Inten-
f. Depress the 2 dRl0iv display mode button on the S I ~ Vuntil the carrier t o noise amplitude retio is optimized
,
analyzer and Wsition the baselme of the d~splayt o the
battom graticule line w i t h the Ven Position mntrol. Center
the display with fhe Horizontal Posit~on control. d. Use the 10 dBlDiv display mode and check for a peak
carrier to noise ratio that i s 50 d B or mwe.
g. Now depress the 10 d6lDiv [LOG] display ~ s h -
button on the analyzer. D splay should now resemble that e. Check the display f o r I M p r d u n s abwe and &low
shown in Fig. 2-1. the picture carrier b y tuning slowly either side of the carrier
sigral or w i t c h t h e center frequency from Center t o Star?
position. Once a beat IS located, campare the peak video
carrier level to the peak intermodulation (beat) signal level.
See Fig. 2-2.
When the ocifilasrope has s CR T with P7 phosphor, a
viewing hood will heb shield ambient light and
enhance the display infwm8tion. f. Check ta ensure that the beat signal is not a pcduet
of the 7Kll amplifier by chang~ngthe input attenuation
(REFERENCE LEVEL) a few dB kg.. 3 dB), If the change
2. Calibrate the sweep man and rsference leuel, using the of the beat signal amplitude level is, rnwe than the Input
7Kll Calibrator signal and the p m c d u r e described i n the menuatlon change, the 7 K l l amplifier 16 p r d u c i n g the
Spechum Analyzer manual. signal.
APPLICATIONS
The gain and 75 R to 50 fl conversion o f the 7 K l l
provide the inaeased sens~tiuitvthat is necessary for the
Spectrum Analyzer (7b12) t o make all CATV performance
tests. Tektronix "Proof o Performance" brochure provides
f
procedures for making these measurements. The following
describes a typical application for the 7 K f t17L12.
Sensitive Intermodulation Measurements:
a. Connect the test point of the CATV system to the
7K11 R F INPUT oonnector.
b. Select a Frequency SlanlDiv x, the spectrum of one
channel is displayed (0.5 MHz). Tuns the S w r u m
Analyzer Genter Frequency t o the center of the channel. ~ i 2.2. o@ley showing Intsrmodulationabove thepictunurrier.
g
PERFORMANCE CHECK
Introduction Spectrum A d y z s r
Yhis section verifies the opwational prformance of the Center Frequency 500 MHz
7K11 t o the characteristits apecifid in the Specifications
section. Ver~fication f the electrical characteristim requires:
o Reference Level
mphisticafed test equipment; hweuer,an inwming accept- (RF Attmuatcx at 0 dB) -30 dBm
ance h e c k procedure is provided i n the first fmrtion of this Display MDde TO dBfDiv
section to h e c k the instrument e r a t i o n . This pocedure
will not measure specified parameters. The second portion Freq. SpanlDii 100 MHz
of this section provides a list of test equrpment and
Resolution 3 MHz
p r o c e d u r ~ for measuring the specified pararnetws and
characteristics. TimelDiv Spectrum or 10 ms
OPERATlONAL CHECK AND
1NSTRUME'NT FAMILIARIZATION
This W r t i o n contains a sequence of procedures that
checks the instrument operation and will help farniliar~ze
you w i t h the instrument operation. Bemuse the 7Kll
Calibrator and anenuator are very accurate, they are used
as the reference for this orwrational checkout.
Preliminary Preparation
Perform the Preliminan/ Front Panel Setup Procedure
that is described in the Operating tnsrructions so the system
display (amplitude and frequencv span) is calibrated.
1 Check F r e q u e n c y Range (30 MHz to 890 MHz)
.
a. A w l y the CAL OUT srgnal through the 75 n,5 112
inch cable, t o the RF INPUT and mnnect the RF OUTPUT
Fig. 31. 50 MHz mrl(msn C r O s 8 1000 MHz d i 4 . y .
to the Spectrum Analyzer RF l n w t through a 50 2 waxial
!
mble.
c. Check the 1000 MHz span for 50 MHz marksrn out t o
900 MHz. Marker amplrtude w ~ l ldecrmse towards the
b. Set the 7 K l l and Spectrum Analyzer selectors as u p w end of the spectrum. Sas Fig. 3.1.
follows:
7K17 2. Check tho Calibratar Reference Lwsl
REFERENCE LEVEL +TO dBmV T h i s is M dB a. Change the Spectrum Analyzer Display M d e to 2
above the calibrator t30 dBiDiv. Tune the Center Frequency to the 50 MHz
dBmV reference level so fundamental. Unwuple the Freq SpanlDiv from the Reso-
harrnoniu of the funda- lution and open the display to 10 MHdDiv. Resolution
mental will spread across shauld remain at 3 MHz. Change the 7 K l f REFERENCE
the 900 MHz spectrum.) LEVEL t a +30 dBmV.
b. Disconnect the cable bstween the 7K11 RF OUTPUT c. Tune the 50 MHz signal to the csnt6-r o the graticule,
f
and the S m r u m Analyzer RF I n w r and a w l y the then open the display by decreasing the Freq Span/Div to 2
Speetrum Analyzer Calibrator signal m its RF Input. Note MHz.
the amplitude of the 50 MHz, -30 dBm sfgnal,
c. Nwv apply the 7K11 RF OUTPIJT t o Spscfrum d. Adjua the signah amplitude with the Spectrum
halyrer lnpm the CAL OUT (+= dsrnv)to its
RF and Analyzer Variable Gain wntml t e a graticule rderenca line
AF INPUT. *mplimde aifimenm b m e n the lea." division blmme top line).
ona
calibrator signals should be slight.
e. Check the 7K11 attenuator by increasing the settings
in 10 dB steps a h +30 dBmV while dmearlng the
MOTE Spectrum Analyzer RF aaenuamr satting in 10 dB incre-
ments and notlng t h e difference in signal amplitude. Now
6%zwse of h 9 additive rohwmes of the 7K11 and decrease me 7Kll attenvator settings below +30 dBmV
Spectrum Analyzer CBIibmtom, PIUS the ?Kll e m - and increase tho analyzer RF attenuator sewings and note
uamr and mplifier, it is impmtical to d I i & the difference. Difference b e e n the m should not
o
k on& an opwational check.
timitt. Phis comparrparrmn ex& 15 dB.
3 C W the Attenustor
. f. Rwurn the attenuamrs to + IdBmV a d 30 dB.
X
Witch t o the 2 dBlDiv display maie and rerctablish a
signal reference leval with the Variable Gain control.
NOTE
rite ateemator BEEUW is checked at the fact005
73is check will d e m t ~ o m p o m faiIum bur It m1
t 7
g. Ch& the 1 dB steps of me J K l l attenurnor by
nor check the tolemne chammistks, I f IYW sder-
noting the M a w of signal amplitude on the display as
a m draracrerisrics are ta b ch@ckeded referem
e a
the attenuation is increased.
sttenvator mlibreted b y the ww or mwrufmturer to
spew'fiwrions more ?&id than n' 7KT 7 artertuamr
m
musf be used.
4. Check Sensitivity (4
-3
d0mV at 3 MHz
Resolution) I
a. Apply the 50 MHz, +30 dBmV signal to the RF
INPUT and mnnect the RF OClfPUT t o the RF lnwt of a. h i t c h t h e Spectrum Analvmr Display Mode to Lin
the %%?rum Analyzer. and sdd 30 kHz of Video Filter.
b 58t the front wnel mmmls ar follows:
.
b. Incream tho 7 K l l amnuator setting 45 dB [ R E F E R -
ENCE LEVEL t o 75dBrnW). NOWinaeane the Spectrum
7Kll Analyzer IF g i n (selector and Variable) setting until the
average noise floor on the display rises one division.
REFERENCE LEVEL +30 dBmV
Sr
-n Analyzar
RF Atrenuam 30 dB e. Check that the amplitude of the signal is at least
twice the noiw level ( > 2 div). See Fig. 32.
R d w t m Level -20 dBm
Display M d e 10 dBIDiv
Freq. SpenlOhr 5 MHz Thls wrnplstes the operational check of the inrtrumentls
performance. If you desire to validate the specified
Resolution . MHz
3
parametws bhich requires swhiaicatsd test equipmnt),
TimelD'w Spectrum or 10 d D l v wntinue to the next part of this peaion.
NOTE: This equipment is also required to recalibrate the
instrumena.
1. Spectrum Analyzer ensemble (Oscillosmpe and f P 1 2 or
7L13 Spectrum Analyzer). NOTE: Storage or variable
pe*sistence osciHompas are desirable for Spectrum analysis.
Tektronix 7000-Series storage or var~able pwsistence
oscilloscows (7613. 7623, 7313) accept three plug-in
widths. The 7L13 Spectrum Analyzer requlr%s three plug-in
widths; therefore, the 7 K l l f l L 1 3 ensemble must be used
with non-nor* rna~nframss such as 7704k and 7904.
2. Leveled sweeper or signal generators that m e thevr
frequency range of 30MHz to 890MHa. (Use a POWW
meter to w i f y that the generator output remalns constant
ouer this frequenq range.)
a) Hewlea Packard Model 86BOA with 86602A RF
Section; o
r
PERFORMANCE VERIFICATION OF b) Hewlett Packard Model g08E (10 MHz t o 480 MHz)
SPECIFIED CHARACTER ISTICS plus Model 611A.
The following procedures describe how to measure the
7 K l l characteristics as specifled. It does not include The Model 612A does not have a leveled output; therefore,
internal adjustments or checks. I f the Instrument falls t o b must be adjusted manually as the frequency is changed.
meet s p e c l f ~ dperformance requirements, the djustment
procedure will be found in the Service section under
Cafibratlon. 3. Vector Voltmeter w i t h a frequenw r a g e of 50 MHz, t o
measure the Calibrator t30 dBmV output level tolerance:
Hewlert Packard Model 8405A.
Hirtotory Information
4. Digital Counter ta check 50 MHz accuracy of the
The instrument and manual are continually evaluated Mibrator: Tektronix 7 0 1 4 Digital Counter with a readout
and updated. Circuits and manual procedures may be 7000-Serlsr oscillompe, or a DC-502 wlth the
d i f bed. lnformat~on applicable to earlier instruments are M-500-Ser~es.
included either as dev~at~ons l t h ~ nthese steps or as a
w
subpart o f the steps. These mdifications are addd at the
back of the manual as insem or indicated i n the prowdure. 5. Type BNC 50 t o 75 ! Minimum Loss Attenuator:
2
Tektronix Part No. 01 1-0057M1.
Equipment Required and Rewrnmendd 6. Two 5:1, 50R Attenuators: Tekuonix Part No.
01 10oMI-01.
The f o l l o w i ~
test e q ~ i p m e n tand fixtures are remm-
mended to perform this portion o f the prformance check.
Test equipment specifications are the minimum require-
7 . Two 18 inch, 50 2 low loss maxial ca3las with BNC t o
!
ments for accurate checks. Substitute equipment must
BNC connectors: Tektronix Part No. 0 t2407600.
equal or exceed these specifications.
8. BNC "T" Connemor: Tektronix Part No. 103US3040.
The fixtures (attenuators, etc.) are used where necessary
t o facilitate the prooedure.mese fixtures are avatlable from
Tektronix, Inc., and can b ordered through your local
e 9. 75 Feedthrough Termination: Tektronix Part No.
Tektronir Field Office or representative. 01 1 0 0 5 5 0 0 .
PERFORMANCE CHECK 4. Chtrek the Frequency Range and DispFay Flat-
m#s (*2 dB, 30 MHz to 830 MHz, +1 dB, 50 MHz
1. Check the Callbmtor Frequency (Accuracy 50 t o 300 MHz).
MHz 20.01%)
a. Set the 7 K l l and Swctrurn Analymr m t r o l s as
The frsquency d the calibrator may be checked by an follows:
wcurate frequency counter, such as Tehronix 7D14 Digital
Counter Plug-In Unit with a readout 7OOOSwies Oscillo-
7K11
scope or a DC602 with T M W + S e r i e s . No p r d u r e for
th~s chmk is provided. because the CAL OUT signal m n 'be REFERENCE LEVEL 10 dBmV
connected through the CATV Preamplifier unit to the input
of the muntar a n d the frequency readout notd. Spcfmm A n d m
Canter Frequency 50 MHz
Refmnce Level
(RF at 0 dB) -30 dBm
2. Check Calibretor Output (+30 dBmV 10.3 dB)
Display Mods 2 dB/Div
The output of t h e mlibretw mnteins harmonim; them- Freq. SpanlOiv 100 MHz
fore. direct mwrement i s not wssible.
Resolution 3 MHz
TimelDk Spectrum or 10 ms
V m x ~ d w Method IHmlmtt PldEad Ma& 8405A
V
Veaw Woltmerer)
b. Apply the output of a leveled sweeper or signal
generator W~rougha 50 Q m 75 D Minimum Losn Atten.
uator, tophe R F INPUT of the 7 K l l . Connect the RF
a. Terminate the "A" probe with a BNC 75hb feed+ OUTPUT to the RF lnput of the $petrum Analyzer.
thmugh mmination and connect the probe, thmugh t h e
termination, t o the CAL OUT wnnectw on the 7 K11.
c. Tune the w w p r or signal generam to 50 MHz and
b. Witch t h e Vector Voltmetw frequency ta 50 MHz. adjust t h e o w t for a signal rsfermw level of appmx-
imatab 5 divisions on thedisplay.
d. Check t h a frequency r a w and flatness d the
c. Clmk for an RMS readlng between 3 1 2 mV to 32.1 7K1 IISpectrum Analyzer enmblw, by weeping or tuning
mV (+a dBmV i s 31.6 mV RMS into 75 Q). Ifo u t m is the signal generator($) from 30 MHz to 890 MHz. Display
out of specification. refer to Calibrator Output adjustment flat- must be withln 1 dB from W MHz to XIO'MHY
in t h e Calibration Rocedure. wmh refarence t 50 MHz. and within 2 dB from 30 MHz to
o
890 MHz. Frequency range must equal or exceed 30 MHz
to 890 MHz.
3 Check RF Attmuator Accuracy
. Within
* 0 2 dB + 1%of the dB readout] 5. Check Intermodulation Distortion
The 7K11 will not degrwle.the IM performance ~ c i f i -
ations of the Spectrum Analyzer. lmerrnodulation distor-
tion from two O dBmV signals isdown 80 dB or m m .
The dF amuatoruccumy is chackedat the f a c w
m ansum thm it jS within ~pe~ifications.Srep #3 in
the first portion of rhis section will detect any One mMhod of checking this specification is to h e c k
mmpomr fa;lum m,*tfr/p the ptremuatof but it wit1 rh6 7 K l l/Spectrum Analyzer ensemble to ensure that the
not check the tolerance nharxseristics. I f tha exact 1M distortion characteristics of the Spectrum Analvwr have
a m u a t i m error of rhs ~ I e c t o ris required, a not been degradd. Check by performing the procedure
reference ettenuatw, mfibrated by the user w mmu- demibed in the Spectrum Analym manual. NOTE: Use a
fecturer ta mwe rigid specifications than the 7K7 l 50 R to 75 Minimum Lops Artenuator between the 50 n
must be used,
RF a n e w ~ m f , signal sour- and the R F lNPUT of the 7K11.
Over the linear opermirrg range o f the 7K11 amplifier.
the gain remains relat~velyconstant or o n a t : l ratio. The
ratio of intermodulat~on prducts (3rd order) from twoor REFERENCE LEVEL *30 dBmV
more Input s~gnals IS about 3: 1. Thls analogy is used t o
extrapolate t h e tM distortion figure of the 7K11 by the
following procedure. Display Mode 10 dBfDiv
RF Attenustor 0 dB
Reference Level -30 dBm
a. Apply two signals within t h e frequency range of the
7Kll and separated awroxrmatelv 2 MHz t o 10 MHz, Video Filter 30 kHz
through two 5X attenuatorr Ifor lsolatlon). a BNC "T" Center Frequency Tuned midway between
mnnector, then through a 50 R t o 75 fl Minimum Loss the two applied signals
Attenuator, to me 7K1 T RF INPUT. Fig. 3 3 illunratec this
setup. Freq SpanlDiv and Span should be wide
Resolution enough to observe the m o
i n w t signals and their I M
~ o d u c t s . Resolution W
b. Set the front panel mntrols a d seleaors as follows: for optimum sensitivity.
SwmI Germator 7OM) Sorims U ~ S~ma!
F
-
500 MHz 1OMI MHz 03rllloxope Germtator
l O M H z 500MHz
-bX mmnuatws
-
far ~rolntlon
BBC '7" cnnneclor and
50 11 t o 75 R manlmum
loss attonuntor
Fig. 3 . Equipmorn astuvmnd eonmztlornnseuwy to mmwm Intermodulation dktwtlon,
3
C. Adjust the output of the two signal sources until b t h
signafs are full screen or at the reference level. 7
Wheo Ihe 7 K f 7 REFERENCE LEVEL is+3OdBmV,
the input to the amplifier stage i s 0 dEm V, because
the attenuator is between the smplifier sod the RF
INPUT mnnEcfor.
d. Decrease t h e 7Kll REFERENCE LEVEL (atten.
uator) setting in 10 dB steps and innease the Spectrum
Analyzer R F Anenuator retting i n TO dB neps until the
intermodulation s~gnalsappear on the display. See Fig. 3-4.
NOTE: Verify the 2:l ratlo of the IM products by noting
the amplitude increase for a 10 d B change I n the 7Kll
A I M products on ellhe* rlde of IWO slgnals
input leuel. I f the amplifier i s nof ovwdriven, the amplitude
level of the I M uroducts will increase 20 dB w ~ t h change
a
o f 10 dB attenuation. When the amplifier is ouerdrhven.
additional spurs wrll be generated erther ride o f the I M
signals. I f this occurs, inaease the 7Kll RF ATTEN-
WATOR setting and deerease the Spectrum Analyzer RF
Attenuator setting.
3. Note the level of the IM signals; then determine by
extrapolating, the level of the I M signals below CidBmV.
For example: A change o f 20 dB In attenuation would add
40dB to the noted level of the I M srgnals below the
reference level. If the level of the It4 s~gnals1 45 d B below
s
the t o p of the gratlwle. w i l h the r~gnalinput to the 7 K 1 1
20dB above the referenoe level. the ~ n t e r w l a t e d I M
distortion w w l d equal (45 dB + 40 dB1 85 dB.
B An overdrlven arnpl~flergenerates addrt~onalqrurll
This completes the uerformance ch& for the 7K11. I t
will now perform within the specifications described in
Section 1. Fig. 34. Ollplay o l I M d ~ s t o n i o n an merdrivsn r m ~ l f l a r .
and
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