M31 - Khz Steps - Wavetek 3000 Instruction Manual

THEORY OF OPERATION
3 .11 .2
DIVIDERS
The frequencies below 40 MHz are pro-
duced by a series of TTL counters . A
"divide by 4"
produces the 10 MHz out
put for the phase- locked loop in the
optional high stability reference . This
frequency is
further divided as shown
in Figure 3-16 to provide the 1 MHz, 2
kHz and 1 kHz outputs .
3 .11 .3
MULTIPLIERS
The 40 MHz CW is fed to a harmonic gen-
erator which produces the "comb" output .
From the 40 MHz comb, 120 MHz is selected
and applied to another harmonic genera-
tor .
A sample of the 120 MHz comb output
is also fed to a
filter which provides
the 1440 MHz output .
3 .12
M31A - kHz STEPS
The input to this module is the BCD data
from the front-panel "kHz" switches (to
3-16
21WHz
Figure 3-16 .
/MHz
M30 - Crystal Reference
3 .12 .1
VCO
/ A042
40 Milt
COME
3 .12 .2
PHASE LOCKED LOOP
120 MWs
?p0 M.fis~
COMA
/440 MVL
the right
of the decimal point) . The
output
frequency is (10 MHz - Sk kHz),
where Sk is the number indicated by the
kHz switches .
If the FREQUENCY is set
to 333 .333
MHz,
for example, the M31A
output is 9 .667 MHz .
The block diagram
of the M31 is shown in Figure 3-17 .
The output frequency
is generated by a
Voltage
Controlled Oscillator which is
tuneable from 9 .001 to 10 .000 MHz .
Including the VCO in a phase-locked loop
permits accurate programmability . The
VCO tuning voltage comes from the Phase/
Frequency
Detector circuit .
A 1 kHz
signal from
the Crystal Reference
is
applied to one input of the phase detector
(IC9) .
A sample of the VCO input is
divided by the Programmable Divider, . and
the result is applied to the other input
of the phase detector .
Any difference in