Wavetek 3000 - Oscillator Circuit; M30 - Crystal Reference; 40 MHz Oscillator

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MODOLATINfr
S1GN'A
L
positive source is
referenced to the
negative source
so that the instantan-
eous currents
in both sources are equal .
3 .10 .2 Oscillator
The
change in output current is
directly
proportional
to the change in input
vol-
tage to
the circuit . The input
voltage
mayvary
between -5 and +5 volts
. The
circuit
is designed for a very
linear
current-out
vs . voltage-in curve .
The square wave output
is
produced
by
the combination
of an integrator and a
hysteresis switch .
The integrator con-
verts a square wave
to a triangle wave .
The triangle
wave causes the hysteresis
switch to produce
the square wavewhich
is fed back to the
integrator .
The integrator
is made up of a current
switch and a
capacitor . The square
wave applied
to the current switch
causes
a square
current signal to
be applied
to the capacitor .
Positive constant current
produces an
increasing voltage ramp
on the capacitor
and negative
constantcurrentproduces
Figure 3-15 .
M29-1 - FM
Reference
THEORY OF OPERATION
l . S- 2 . S Mf/z
a decreasing
voltage ramp .

For a square
wave
input, therefore, the output
is a
triangle wave .
Changing the magnitude of
the "currents",
by changing
the input voltage to the
module, changes
the rate at which the
capacitor charges and
discharges to the
hysteresis points
thus the frequency of
oscillation
changes .
3 .11 M30 - CRYSTAL
REFERENCE
This
module supplies reference frequen-
cies at
1
kHz, 1 MHz, 2 MHz,
40 MHz
and
its harmonics, 1200 MHz (from 120
comb)
and 1440 MHz to the phase
locked loops
in the instrument .

These signals are
produced
by a 40 MHz crystal oscillator
and a series of dividers and multipliers
.
See Figure
3-16 .
3 .11 .1 40 MHz Oscillator
This crystal oscillator
is the heart of
the accuracy of the
frequency determining
circuits
in the instrument . It is tem-
perature compensated
for frequency
stability .
A levelercircuit causes the
oscillator output level to be the
same
in all M30modules .
3-15