Wavetek 171 - Page 17

quency
1s
divided
by
a multiple
of
10,
as
controlled
by
the
FREQ
MU
LT range switch, and fed
to
the
function generator
phase
lock loop
(figure
4-1).
A
1
Ok
to
200
kHz
output
is
used
to
create
the
F
N
signal
which gives rapid function generator response
to
frequency
changes. A one-shot changes
the
signal
to
fixed width pulses
whose spacing
is
frequency dependent. These are converted
CLK
KILL
XTALOSC/
+4
PHASE
to
a frequency
dependent
voltage
level
at
the
F
N
converter
output.
One
pole
of
the
function generator/synthesizer mode switch
furnishes
the
ground signal
CLK
Kl LL. CLK
Kl
LL
stops
synthesizer
loop
activity when
the
instrument
is
in
function
generator mode
or
set
on
X
1,
a
dial-only
range. Lamps in-
dicating
mode
are
also controlled
by this
CLK KILL.
REF
OUT
TTL
BUFFER
1
MHz
~
(OPTION)
5V
REG
1.0000
kHz DETECTOR
1
MHz
EXT/INT
REF
SELECTION
+1000
~
1 MHz
EXT
REF
IN
FCTN
GEN
~CLK
V e -
..--
KILL
SYNTHE-
SIZER
1.0000
kHz
0.1000
- 1.9999
DIGITAL
SWITCH
20
Hz
LPF
FN
FN
ONE-
10k •
200
kHz
CONV
SHOT
FCTN GEN
CLK
·I
INDICATOR
I
~
1+26V
Kill
SELECTOR
SYNTHESIZER
1M-20MHz
+10
+10R
FREQUENCY
RANGING
R
•
0-5
FREQ
MULT
SW
Figure 4-5. Synthesizer Phase Lock Loop
CLK
KILL
8M-20MHz
SYNTHESIZER
LOOP
FREQUENCY
(REF)
4-3