User's Manual
1 1 7 B 2 0 W at t V H F H igh Band Transla t or Syst e m Align m ent Procedu r e
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The Translat or has been fact ory aligned and should not require adj ust m ent t o obtain norm al
operat ion. For a Detailed Alignm ent Procedure of each Tray, refer to the Receiver Tray or the 20
Watt Upconverter/ Am plifier Tray sect ion of t his Manual.
SYSTEM SET UP
The syst em set - up includes adj ust m ent of linearity t o com pensat e for any am plifiers nonlinear
responses. The Translat or should be switched On initially into a 20 Watt dum m y load t o verify that
the system is funct ioning properly.
I n the VHF Upconvert er/ Am plifier Tray, check t hat the ALC Auto/ Manual Switch (S1), located on
( A10) the ALC/ AGC Board ( 1067- 1116) , is in Aut o. Switch the On/ Off Circuit Breakers locat ed on
the front panels of the Receiver and the 20 Wat t Upconverter/ Am plifier t o the On position. Swit ch
the Translator to Operat e and adj ust t he ALC Reference Pot (R47) , or ( R2) the Front Panel Power
Adj ust , t o obt ain a Detect ed I F Output Volt age Level of + 2.0 VDC at TP3 of t he ALC/ AGC Board.
The Front Panel Met er in the ALC Reference Voltage position should also read + 2.0 VDC. Switch
the ALC Auto/ Manual Swit ch ( S1) to Manual ALC and adj ust the Manual ALC Pot (R17) t o obtain a
Detect ed I F Output Volt age Level of + 2.0 VDC at TP3 of t he ALC/ AGC Board. Swit ch the ALC
Auto/ Manual Swit ch ( S1) t o Aut o ALC.
I n the VHF Upconvert er/ Am plifier Tray, check t hat the AGC Switch (S2) , located on ( A10) the
ALC/ AGC Board (1067-1116) is in Aut o. Preset t he AGC Aut o Gain Pot ( R96) and the AGC Manual
Gain Pot ( R101) t o m inim um ( CCW) . Swit ch the Front Panel Aut om at ic/ Manual Swit ch to Manual.
Switch the front panel Met ering Switch, locat ed on the 20 Wat t Upconvert er/ Am plifier Tray, to t he
% Visual Output Power position and adjust the AGC Auto Gain pot ( R96) located on ( A10) t he
ALC/ AGC Board (1067-1116) to 100% on the m eter. Swit ch the AGC Switch (S2) t o t he Manual
Posit ion and adj ust t he AGC Manual Gain pot ( R101), located on t he ALC/ AGC Board, also for 100%
on t he m et er. Swit ch S2 back t o Aut om atic. The Front Panel Met er of t he Upconvert er/ Am plifier
Tray in the AGC Detect or Volt age position should read +.3 VDC, but t he exact values are writt en
on t he Final Test Dat a Sheet for your Syst em .
Connect a Dem odulator and Oscilloscope or ot her m onit oring equipm ent to m onitor the different ial
gain and different ial phase of the out put signal. I f a synchronous dem odulator having a quadrat ure
video output is available, it m ay be em ployed with an X- Y Oscilloscope to display incidental carrier
phase m odulation ( I CPM) . As shipped, the Translat or was preset t o include linearity ( gain vs.
level) predist ort ion which w as adj ust ed to com pensate for the corresponding non- linear dist ort ions
of t he solid st at e am plifier devices in the Translator. Swit ch S1 locat ed on ( A11) the Linearit y
Correct or Board (1161-1116), t o t he On position.
SYSTEM SET UP OF LI NEARI TY
The I F linearity correct ion funct ion consist s of three non-linear cascaded st ages, each having an
adj ust able m agnitude and a t hreshold, cut - in point. The t hreshold adj ust m ent determ ines at what
I F signal level t he corresponding corrector st age begins t o increase gain. The m agnit ude
adj ust m ent determ ines the am ount of gain change for t he part of the signal which exceeds the
corresponding t hreshold point . Because the stages are cascaded, t he order of correct ion is
im portant .
The first st age should cut -in nearest t he whit e level, wit h t he cut - in point of the second st age
m oving toward black, wit h the last st age prim arily st ret ching sync. Linearity Correct or Board pot s
R3, R13 and R23 control t he overall gain of each st age. They were preset during Final Test at t he
Fact ory and should not require adj ust m ent. I f m oved accident ally, typical set t ings are R3, R13 and
R23 m id- range.
SYSTEM SET UP OF LI NEARI TY - CONTI NUED