Wavetek 3000 Instruction Manual page 40

THEORY OF OPERATION
0
0
0-
MHz
The filter after the mixer #2 blocks all
the outputs of the mixer except the lower
frequency signal containing the VCO error
it sends a voltage to the flasher cir-
cuit .
R 9.9
100 . 000
/00.005-
04'r,-417- E.PEQUENG'Y-MNZ The leveler circuit maintains a constant
input amplitude to the phase detector
by controlling the amplitude of the
Figure 3-22 . M34 - Frequencies input from M9W wide oscillator . The
(Expanded) input to
the phase detector
(about 10
MHz) is peak detected and compared to
000) . Figure 3-22 shows signals A thru a DC reference in the leveler circuit .
F for a case when the kHz switches are
The leveler circuit controls a PIN diode
not 000 .
attenuator which is between the VCO in-
put and mixer #1 .
1019.000 OUTPUT FREQUENCY - MHz /OQ 003
MNz
information . When the unit is unlocked
the filter passes up to 20 MHz (to be
able to capture over the 20 MHz range
allowed for analog tuning) . Once the
/298 .000-
loop is locked the filter decreases to
10 MHz to further eliminate phase locked
68 NINZ
loop related spurious signals .
170 .000
3 .15 .3 Auxillary Circuits
MNz
I
The "speed-up circuit" is activated when
/6 9. 9 9 .T
the phase locked loop becomes unlocked .
160 MNz
L
The output of this circuit is sent to
the M9W to cause the VCO to be tuned
/0
faster by the analog voltage .
MHz -
The "unlock" amp monitors both the tuning
9 995-
voltage from the phase detector and the
leveler voltage to detect an unlocked
10
-I
condition of the M34 .
When unlock occurs,