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Calibration — Type 5 1 6

Delay Line Adjustment Procedure

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(b )

Fig.  6 -1 4 .  Determ ining  the  am ount  of  w rin kle   in  the  displa y.  The
ab errations  in  (a )  are  caused  by  a  m isadjustment  o f  a  group  of
capacitors;  the  single  bump  in  (b )  is  caused  by  the  misadjustment
of  a  single  capacitor.

correct type of waveform is shown in Fig. 6-15 (a). The
rounded-corner type of waveform, shown in Fig. 6-15 (b) is

the  result  of  insufficient  high-frequency  compensation,  and
the  overshoot  condition  shown  in  Fig.  6-15  (c)  is  the  result
of  overcompensation.

There are four major steps in adjusting the Delay Line

and the Vertical Amplifier in the Type 516 Oscilloscope.

These are:

1. Presetting the adjustments

2. Establishing a level display

3. Removing the wrinkles

4. Compensating the amplifier

It may be necessary, in some instances, to perform all of

the steps listed in these instructions. In other cases, and

particularly where the degree of misadjustment is minor,

the first step can usually be omitted.

Presetting the Adjustments.

If the displayed square-wave

on the crt indicates that the Vertical Amplifier and the Delay

Line  are  considerably  out  of  adjustment,  presetting  the  con
trols  before  starting  the  adjustment  procedure  will  generally
render  the  best  results.

The variable inductors, L455 and L555, in the Vertical

Amplifier,  should  be  preset  so  that  the  slugs  are  positioned
deeper  into  the  coil  form  than  the  windings  of  the  coil  ex
tend.  When  the  slugs  are  positioned  below  the  coil  windings,
light  can  be  observed  between  the  top  of  the  slugs  and  the
bottom  of  the  windings.  Presetting  the  inductors  in  this  man
ner  reduces  their  effect  in  the  circuit,  and  the  adjustment  of
the  Delay  Line  is  simplified.

The variable capacitors in the Delay Line should be preset

so  that  the  top  of  the  adjusting  screw  extends  about  one-
quarter  of  an  inch  above  the  top  of  the  contact  springs.  The
important  characteristic  is  that  the  tops  of  all  the  adjusting
screws  should  be  at  about  the  same  height,  both  after  the
preset  procedure  and  after  the  final  adjustment.

The inductors and the capacitors in the termination net

work  (L485,  L486,  C485,  C486)  are  the  first  to  be  adjusted  in
the  adjustment  procedure;  for  this  reason  it  is  not  necessary
to  preset  these  controls.  However,  it  is  important  to  check
the  inductors  for  balance.  The  slugs  in  each  inductor  should

be set to the same depth within the coil form.

Establishing a Level Display.

The reference level for the

displayed waveform is established by that portion of the

(a )

(b )

Fig. 6 -1 5 . Determ ining the squareness o f the corner a n d le a d in g edge, (a ) shows

the  idea l  w aveform ;  the  rounded  corner  in  (b )  is  the  result  o f  in sufficie nt  h ig h -fre
quency  compensation  in  the  a m p lifie r;  an d   the  overshoot  in   (c)  is  the  result  o f
excessive  high-frequency  compensation.

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