FMALIGNMENT
ADJUST
Top(secondary)
andbottom
(primary)of
T1.T2,T3
Primaryand
secondaryof
T4
Secondary
(top)
of
T-5
-4
L-4
C-2,
C-3
L-1,L-2,
L3
Primary(bottom)
ofT-5
L-2,
C-3
Mutingthreshold
control
TEST
LIMITS
Maximumpos-
siblenegative
voltage
Maximumpos-
siblenegative
voltage(should
be20to30
volts)
Adjustfor0 volts
Maximumnega-
tivevoltage
SAME
SAME
SAME
0.5%distortion
orless
Minimumtilt
IHFMSensitivity
2.5microvolts
for3%total
noiseand
distortion
REMARKS
Beforemakinganyadjustments,setthecontrolsasfollows:
a)InputselectorswitchtoFMmono,
b)VolumecontrolmaximumCCW.
c)MutingpotmaximumCW.
d)MutingOUT.
e)StereolightadjustmaximumCW.
Shunttogroundthewindingnotbeingadjusted.Dothiswitha .01
MFDcapacitorinserieswitha 1Kresistor.Attenuatesignalgenerator
untiloutputvoltageatTP#1islessthan1.5voltswithoneIFtrans-
formerwindingshunted.IFtransformershaveterminal#1marked
witha greendotandarenumberedclockwise.
_
Mutingpot.MUSTbemaximumCW.
Theprimary(bottom)ofT-5shouldbeadjustedonlyifa distortion
analyzerisavailable.
Repeatsteps4 and5 untildialcalibrationisaccurate.
Asoutputincreases,attenuatesignalgeneratortokeepmaximumout-
putatTP#1tolessthan1 volt.
Repeatsteps6 and7 untiloutputisashighaspossible.
Usea strongsignalfromtheFMgenerator.AdjustT-5primaryfor
minimumdistortion.IFA DISTORTIONANALYZERISNOTAVAILABLE,
OMITTHISSTEP.DONOTADJUSTT-5PRIMARY.
Observedirectionoftiltofoverallresponsecurveat105MCand90MC.
If
direction
isthe
same,
adjust
L-2at
100MC
for
minimum
tilt.
Re-check
tilt
at
90MC
and
105MC.
If
direction
isnotthe
same,adjust
L-2(at
90MC)
andL-3(at
105MC)
for
minimum
tilt.
Check
tilt
again
at
100MC.
WithFMgeneratorsetfor2.5microvoltsoutput,placemutingcontrol
to"IN."Adjustthemutingthresholdcontroltothepointatwhichthe
sinewaveonthescopebecomeserratic.
Step11isanoverallsensitivitycheck.Itrequiresa distortionanalyzer
andFMsignalgeneratorwithattenuator.With2.5microvoltsinputat
the300ohmterminals,TP#1voltageshouldbe.45voltsormore.
3
