Wavetek 2001 Instruction Manual page 101

CIRCUIT DESCRIPTION
4 , l l When the 350 kHz (2.35 MHz) s i d e band marker i s ori,
t h e 31.15 MHz o s c i l l a t o r , 98, o u t p u t mixed w i t h
The preceding paragraph, 4.10, described marker 31.5 MHz i n FET, Q9, produces a 350 kHz difference
c i r c u i t s i n general. The c i r c u i t s described below
frequency emphasized by L21, C33 and mixed w i t h t h e
a r e t h e s p e c i f i c markers o f t h e model 2001A and 63.0 MHz b i r d y marker i n 910. C37, 38, 39 and L23
20018.
a r e a low pass f i l t e r which attenuates h i g h e r s i d e
bands.
4 U 1
M66-59,5/1090/?4,5 MHz
T h i s module contains two s i n g l e frequency markers
(59.5 MHz and 1090 MHz) and a s i d e band c i r c u i t a t
4.5 MHz.
The 59.5 MHz marker frequency i s obtained from a
29.75 MHz c r y s t a l o s c i l l a t o r c i r c u i t ( Q l ) . The 2nd
harmonic i s tuned by L4, C6 and coupled i n t o a
tuned mixer c i r c u i t c o n s i s t i n g o f L5, C8 and CR1.
B i r d i e s from t h i s m i x e r a r e coupled through a l o w
pass f i l t e r c o n s i s t i n g o f L6 and C10. I f t h e s i d e
band o s c i l l a t o r i s on, 4.5 MHz C W i s coupled i n t o
t h e mixer through C11. C10 i s tuned t o emphasize
t h e 4.5 MHzvideo, p r o v i d i n g s i d e band marker video
o f about the same amplitudeas t h e 59.5 MHz marker.
Operationof t h e 1090 MHz marker i s t h e same except
f o r t h e harmonic generation s e c t i o n . A 54.5 MHz
o s c i l l a t o r i s doubled by CR3-CR4 and L l l - C 2 1 tunes
t o 109 MHz. 45 a m p l i f i e s harmonicsof 109 MHz, and
545 MHz i s selected by L12-C25. 545 MHz i s coupled
t o t h e mixer diode CR5 where i t s 2nd harmonic i s
emphasized by t h e sweep sample t u n i n g c i r c u i t L13-
C27, w h i c h i s tuned t o t h e d e s i r e d marker frequency
o f 1090 MHz. L18 couples 4.5 MHz from Q8 through
C30 and C29 t o produce t h e 4.5 MHz s i d e bands.
T h i s module contains a s i n g l e frequency marker
63.0 MHzand two s i d e band circuits+.gand?.35 MHz.
The 63.0 MHz marker frequency i s obtained from 31.5
MHz c r y s t a l o s c i l l a t o r c i r c u i t 91, t h e o u t p u t o f
which i s doubled by 42 and 3, and coupled t o t h e
tuned FET mixer c i r c u i t c o n s i s t i n g o f L7, C8 and
44. B i r d i e s from t h i s mixer a r e coupled through
63.0 MHz marker s i z e c o n t r o l R12 t o t h e low pass
f i l t e r C11, 12 and L10 and then t o t h e marker amp-
l i f i e r module.
4,11,3 M6H-5, 20, 30 MHz
C i r c u i t f u n c t i o n s f o r these markers a r e l a b e l e d on
t h e M6H schematics. A tuned C o l p i t t s o s c i l l a t o r w i t h
f h e c r y s t a l o p e r a t i n g a t i t s t h i r d o v e r t o n e frequency
i n a s e r i e s resonant mode d r i v e s a harmonic genera-
t o r 42. The CW comb i s mixed w i t h sweep sample i n
CR1 and t h e r e s u l t a n t b i r d i e s a r e a m p l i f i e d b y Q 3 and
Q4, and coupled through t h e S I Z E c o n t r o 1 R15 t o p i n
3 o f t h e module.
T h i s module contains a 1 MHz harmonic marker and a
s i d e band 200 kHz marker generator.
A 1 MHz s e r i e s c r y s t a l o s c i l l a t o r c o n s i s t i n g o f 91,
Q2 and 43 d r i v e s a harmonic generator, c o n s i s t i n g
o f Q 4 a n d Q 5 , t o nrnduce a CWcomb. The comb i s mixed
w i t h a sweep sampfe i n CR2 t o produce b i r d i e s , which
a r e then a m p l i f i e d by a video a m p l i f i e r c o n s i s t i n g
o f Q6, Q7 and 48. The marker b i r d i e s are coupled
through Q9 t o p i n 7 p r o v i d i n g the 1 MHz marker o u t -
put. A low pass f i l t e r , comprised o f L7, L8, L9
and associated c a p a c i t o r s attenuate t h e 1 M H z o s c i l -
l a t o r s i g n a l , and any s i d e band video frequencies
h i g h e r than 500 kHz. This side band video i s a l s o
used t o produce 200 kHz markers by m i x i n g w i t h t h e
C W comb from 412, i n CR4 and CR5, when 200 kHz B+
i s applied.
The s w i t c h a t p i n 8 s u p p l i e s B t t o t h e 200 kHz mark-
e r c i r c u i t s and i f the 1 MHz switch i s n o t on, a c t i -
vates
t h e 1 MHz s e c t i o n through diode CR3, w h i l e
d i s a b l i n g t h e 1 MHz b i r d y output through Q9. The
1 MHz o s c i l l a t o r provides a c l o c k f o r I C 1 connected
as a 5 : l frequency d i v i d e r t o produce a 200 kHz
C W output. The f i r s t and second harmonics a r e
coupled through Q12 i n t o t h e 200 kHz mixer CR4-CR5.
The 200 kHz s i q n a l and a l l video frequencies above
40 kHz a r e then attenuated by a low pass f i l t e r
he
900 kHz (+.9
MHZ)
s i d e band frequency i s ob- 1 1 2 - ~ 1 5 . The b i r d y i s then a m p l i f i e d by Q13 and
t a i n e d from a 32.4 MHz c r y s t a l o s c i l l a t o r , Q5, t h e coupled through t h e SIZE c o n t r o l R38 t o p i n 11 o f
Output of which i s mixed w i t h the 31.5 MHz s i g n a l t h e module, b r o v i d i n g t h e 200 HZ marker output.
i n t h e FET mixer, 46. C21 couples the o u t p u t t o
t h e 900 kHz tuned mixer L15, ~ 2 7 ' a n d 97 where' i t i s
mixed w i t h the 63.0 MHz b i r d y .
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4.11
The preceding paragraph, 4.10, described marker
circuits in general. The circ~fts described below
are the specific markers of the model 2001A and
2001B.
4.11.1 M66-S9.S/1090/±4.5 MHz
This module contains two single frequency markers
(59.5 MHz and 1090 MHz) and a side band circuit at
4.5 MHz.
The 59.5 MHz marker frequency is obtained from a
29.75 MHz crystal oscillator circuit (Q1). The 2nd
harmonic is tuned by L4, C6 and coupled into a
tuned mixer circuit consisting of L5, C8 and CR1.
Birdies from this mixer are coupled through a low
pass filter consisting ofL6 and ClO. If the side
band oscillator is on, 4.5 MHz CW is coupled into
the mixer through C11. C10 is tuned to emphasize
the 4.5 MHz video, providing side band marker video
of about the same amplitude as the 59.5 MHz marker.
Opera t f on of the 1090 MHz rna rker is the same except
for the harmonic generation section. A 54.5 MHz
oscillator is doubled by CR3-CR4 and L11-C21 tunes
to 109 MHz. Q5 amplifies harmonics of 109 MHz, and
545 MHz is selected by L12-C25. 545 MHz is coupled
to the mixer diode CR5 where its 2nd harmonic is
emphasized by the sweep sample tuning circuit L13-
C27, which is tuned to the desired marker frequency
of 1090 MHz. L18 couples 4.5 MHz from Q8 through
C30 and C29 to produce the 4.5 MHz side bands.
4.11.2 M66-63/±.9/±.35 MHz
This mOdule contains a single frequency marker
63.0 MHz and two side band circuits:!:.. 9 and:!:.. 35 MHz.
The 63.0 MHz marker frequency is obtained from 31.5
MHz crystal oscillator circuit Q1, the output of
which is doubled by Q2 and 3, and coupled to the
tuned FET mixer circuit consisting of L7, C8 and
04. Birdies from this mixer are coupled through
63.0 MHz marker size control R12 to the low pass
filter C11, 12 and L10 and then to the marker amp-
1 ifi er modul e.
The 900 kHz (+.9 MHz) side band frequency is ob-
tained from a 32.4 MHz crystal oscillator, Q5, the
output of which is mixed with the 31.5 MHz signal
in the FET mixer, 06. C21 couples the output to
the 900 kHz tuned mixer L15, C27 and Q7 where it,_is
mixed with the 63.0 MHz birdy.
CIRCUIT DESCRIPTION
When the 350 kHz (+.35 MHz) side band marker is on,
the 31.15 MHz oscillator, Q8, output mixed with
31.5 MHz in FET, 09, produces a 350 kHz difference
frequency emphas i zed by L21, C33 and mi xed with the
63.0 MHz birdy marker in 010. C37,38, 39 and L23
are a low pass filter which attenuates higher side
bands.
4.11.3 M6H-5
1
20
1
30 MHz
Circuit functions for these markers are labeled on
the M6H schematics. A tuned Colpitts oscillator with
the crystal operating at its third overtone frequency
in a series resonaht mode drives a harmonic genera-
tor 02. The CW-comb is mixed with sweep sample in
CR1 and the resultant birdiesareamplifiedbyQ3 arid
04, and coupled through the-SIZE control R15 to pin
3 of the module.
4.11.4 M66H-.2/1 MHz
This module contains a 1 MHz harmonic marker and a
side band 200 kHz marker generator.
A 1 MHz series crystal oscillator consisting of 01,
02 and Q3 drives a harmonic generator, consisting
of 04 and 05, to prnduce a CW comb. The comb is mi xed
with a sweep sample in CR2 to produce birdies, which
are then amplified by a video amplifier consisting
of 06, Q7 and 08. The marker birdies are coupled
through 09 to pin 7 providing the 1 MHz marker out-
put. A low pass filter, comprised of L7, L8, L9
and associated capacitors attenuate the 1 MHzoscil-
lator signal, and any side band video frequencies
higher than 500 kHz. This side band video is also
used to produce 200 kHz markers by mixing with the
CW comb from Q12, in CR4 and CR5, when 200 kHz B+
is applied.
The switch at pin 8 suppl ies B+ to the 200 kHz mark-
er circuits and
if
the 1 MHz switch is not on, acti-
vates the 1 MHz section through diode CR3, while
disabling the 1 MHz birdy output through 09.- The
1 MHz oscillator provides a clock for IClconnected
as a 5:1 frequency divider to produce a 200 kHz
CW output. The first and second harmonics are
coupled through 012 into the 200 kHz mixer CR4-CR5.-
The 200 kHz signal and all video frequencies above
40 kHz are then attenuated by a low pass filter
L12-L15. The birdy is then amplified by 013 and
coupled through the SIZE control R38 to pin 11 of
the module, providing the 200 kHz marker output.
4-9
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