Westinghouse Type KR, Installation & Operating Instructions Manual

Page: 8 / 124

which would necessitate increasing the sensitivity
of
the receiver.
Reserve Signal Detector
Due to different types
of operation and supply
voltages, it is not practical
to have
a
calibrated dial
for
this
unit.
However, calibration may
be
made at
installation by recording transmitter output ( either in
db or volts) at various k nob settings of the detector
unit. Then, by adjusting the k nob so as to obtain 10
milliamperes relay current at a remote receiver, any
increase or decrease in line attenuation
may
be noted
as the difference between thE� original setting, and
the setting required to obtain the given 10 milli­
amperes.
25G-Volt Resistor Unit
With the appar atus energized, adjust R-4 in the
250-volt resistor unit so as to obtain 125-volts at
0
t
er
m
i
nals
17
(ne g . ) and 1 9 (pas . ) on the r
e
l
a
y
in
g s
e
t .
Frequency Change
If the frequency is changed in the field, it is
necessar y to change the input filter FL-1 to the de­
sired channel frequency, This filter is of the plug­
in type and may be r emoved by unsnapping
the clamp
and pulling the f ilter out. The transmitter oscillator
crystal Y-2 must be changed to the desired channel
frequency. The receiver oscillator crystal Y-1 must
be changed to the desired channel frequency plus 20
kHz.
Figure 9 shows the connections for the trans­
mitter out put filter. It is necessary to unsolder the
existing connections and make the new connections
per the chart. After com pi eting t he preceding, the
tuning procedure as described under Adjustments for
transmitter and receiver should then b e followed.
Note also that capacitors C2 and C9 in the
transmitt er and receiver crystal oscillator circuits,
respectively, may have to be changed. For fre-
quenci es below
110 kHz, t
he
s
e capacitors a
r
e
270
mm
f
. each. For frequencies of
110 kHz
and above,
the
capacitors are 140
mmf.
e
ach
.
C AUT 10 N
Turn power OFF before removing filters
or transistors, as high transient currents may cause
perm anent damage to the transistors.
M A I NT E N A N C E
Voltage values should be recorded after adjust­
ment in order to establish reference values which will
be
useful when checking the apparatus. The readings
8
will remain fairly constant over an indefinite period
unless a failure occurs. However, if transistors are
changed, there may be cons iderable difference in
these readings without the overall performance being
affected.
Typical voltage and current values are given as
follows. Voltages should be m easured with VTVM.
Readings may vary as much as
±20%.
In the following paragraphs, the transmitter may
be unblocked ( transmitting) by closing the CARRIER
START circuit in the case of HZM relaying, and by
opening tile CARRIER START circuit in the case of
K-DAR and GCY relaying.
1.
For D-C pin j ack m easurements with reference
0
to
neg, d.
c
.,
refer
to Table
1.
2. For transistor D-C measurements with reference
0
to
neg,
d.c.,
refer to Table
2 .
3 . For D-C bleeder measurements with reference
0
to
neg. d.c.,
refer to Table
3 .
4 . For typical RF signal m easurements for re­
ceiver, refer to Table
4.
5. For typical RF signal measurements for
transmitter, .refer to Table 5.
6. Removal of Printed Circuit Board from
Flexitest Case.
To
remove the printed circuit board, unplug J- 15
and
J-16
located near the output filter. Loo sen the
two screws inside the case near the top. Loosen the
slotted
thumb
screws at the lower
P'lrl of the b
o
ard
and pull these screws out
as far
as
th&s
w
i
l
l extend.
Also
r e rr,o
v
e
th e receiver
coaxial ::atle !2<i,�.
Pull board down so as to disengage the terminals,
and lift out.
7. Removal of the Output Filter
After the printed board has been removed, re­
move the screws on the outside of the case at the
bottom. Lift out filter and disconnect the coaxial
cable.
B.
Receiver Filters
Fig. 13 shows t
y
pi
c
al receiver sel ectivity curves
both R F and IF.
If t
h
e
filters are
checked in a test
www
. ElectricalPartManuals
. com