Operating instructions

Th e +20 -vo lt r e gulat or co ns ists of:
br
idg e co nnec te d r ect ifi ers C Rl , CR2,
CR3, CR4; a
filter ca pac it or , CI; a con-
stant cur re nt s our ce, QI; seri es r e gula-
tors, Q3 and CH -QI; a refer en ce elem ent ,
CR6; diff erential a mplifiers, Q5 and Q6;
a de a mp lifier , Q4; an d an ov er- current
p ro tect io n ci rc u it , Q2. P otenti om et er R9
is the co
ntro l for adj us ting the +20 -vo lt
s upp ly to the
pr op er vo ltage .
Th e
-1 2-v olt suppl y is simil ar and th e
unregul at ed +13- vo lt supply is s im ply th e-
fused output of th e brid ge rectifi e r s for
t he -12-v olt supply. P ot entiom et er R27 is
th e control f or adjustin g the -1 2-volt suppl y
,0 the pr op er vol tage . The +5- vo lt suppl y
is de r ived th ro ugh me ans of ze ner d iode CR7
fr om th e +20
-vo lt suppl y.
The au dio input fr om the VOLUl V1E
con t ro l is amplifi ed by I CI and fed to th e
sp ea k er.
\
The ov en- control cir cuit c ontr ols. the
AC pow er supplied to the heat win dings
of the ove n. F ast hea t is co nt ro lled by
the
sn ap- a cti on th er mo stat whi ch o pe ns
a t 65°C. Re
gular hea t is co n tr o lled by
the m er cu ry co lumn ther mo s tat whic h
dos es a t 76. 2°C an d sho rt s out gate Q13,
.vhich s hu ts off th e tr iac and r em oves the
power
fr om the win din g. Wh en the tem p-
e
ra tur e dr ops b elow 76. 2°C, th e co lumn
opens .
Thi s permits the triac to be trig-
ge r ed on the next tim e the AC v olta ge goes
thr ough ze r o. The fr ont pan el OVEN ON
l
amp is en er gi ze d whe nev er the re gular
heat is on.
Th e
Crys ta l Oven As s embl y (Figur e 6 -9 )
is pr ot e ct ed a gainst ove r hea ti ng by the r mal
fus e
TF1. Any time the temper atur e in-
s ide the o ve n exc ee ds 8 1. I OC, th ermal fuse
TFI will ope n and cause the ov en to becom e
in operati ve.
-1-.4 Frequency Error Meter Board
Fi gure 6 -3 is t he s ch emati c di a gr am
of the F r equ ency Err or Me te r boa rd . Th e
pus h- pul l dc ou tput s fr om the discrimin a t or
-md lowp as s filt er are r outed thr ough the
FREQUENCY
BEL OW 40 MHz - AB OVE
40 MHz sw
itc h. Th e sw itc h r ev erse s the
polarit y of the s igna ls to the met er as th e
LO
is above or b el ow t he de s ir ed s ig na l
to be
monit or ed or gen er at ed. The signals
are th en r oute d through th e functi on switch,
th e EXT. MET ERS switch l ocat ed on the
r e ar pan el, the ±kHz (FREQUE NCY le v er)
sw it ch, an d to the cali b ratio n pot enti om eter s.
In th e FR EQ. -DE \'. l\l EASURE pos iti on
of the
fun cti on sw itc h the r an ge of ope ra tion
of th e m
et er is s el ectabl e by th e ±kHz
(FREQ GENCY le ver) sw itc h for ±O. 5 kHz,
±1. 5 k Hz or ±5. 0 k Hz, In the FM 0 1.' CAL. /
CW p
ositions of the function swit ch, th e in-
puts to th e m eter a r e th r ough sp e cifi c r e-
sis to r s to pr ovide fixed r an g es of ±O. 5 kHz,
an d ±5. 0 kHz, r e sp e cti vely. Diodes C Rl
and CR2 pr ovide me t er protec tio n in the
eve nt of ove rd rive .
In th e HARl\I. Al\ IP. TUNING p osit ion
of the fun cti on sw itch, one sid e of th e m et er
is g ro unded and the oth er side is suppli ed
with the dc tunin g volta ge c oming fr om the
H
arm oni c Gene ra tor boa rd .
4 .5 Harmonic G enerator Board
Fi gur e -1 -6 is the block d iagram and
Figur e 6-
-1 is th e s ch em ati c d iag ra m of the
H
ar m oni c Gener at or boa rd. Dep en ding on
c
us tome r r -equir e me n ts , up to 23 c ry sta ls
in a fr equ enc y r ange of fr om 6.2 MHz to
9. 4 MHz can be
install ed in the Cr ysta l
Oven As s
embly. Any one of the se ca n be
se
lec te d by th e CARRIE R FREQlJ ENCY
SELE CT OR switc h. The se le c ted c r ys ta l
is
ca pac iti ve ly coup led to th e mo dif ed
Colpit
ts osc illat or Q8, .and amp lified by Q7.
The output of Q7
is fed to both li mi te r Q5
and e
mi tte r f oll ow er Q6; the l att er feeds
the
CRYSTAL O CT Al"X. IN co nnecto r .
Thi s co nnec to r is a co nve nient mo nito r ing
p
oint f or m e asuring the fr equenci es of th e
c
rys ta ls and a lso se rv es as th e input con-
ne
ct or f or in put s fr om exte r na l cr yst als
(Model l\ICO -6 M ultl - Chann el Osc i llato r).
Wheth
er an inte rn al or a n ex te r na l c ry stal is
us ed as a signa l sou rce , the si gnal is pass ed
thr ough l imit e r Q5, and capac i tive ly cou p led
to tuned a mp li fi er s QI and Q2. The 6. 2 MHz
to 9
.4 MHz si gna ls ar e m ultipli ed by QI an d
tuned by Q2 to give a fr equen cy ran ge of
c
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5601"0015"1