Westinghouse Type KR Installation & Operating Instructions Manual page 89

TYP E K R CAR R I E R SET
quencies below 1 10 kc, these C!J.pacitors are 270
m mf. each. For frequencies of 1 10 kc and above , the
capacitors are 140 mmf. each.
C A U T 10 N Turn power OFF before removing filters
or transistors, as high fransient currents m ay c ause
p ermanent damage to the transistors.
M A I N T E N A N C E
Voltage values should be recorded after adjust­
ment in order to e stablish reference values which will
be useful when checking the apparatus. The readings
will remain fairly constant over an indefinite period
unless a failure occurs . However, if trans i stors are
changed, the re may be considerable differ ence
the s e readings without the overal l performance being
affected .
Typical voltage and current values are given as
follows. Voltages s hould be m easured with VTVM.
Readings m ay vary as much as ±20 %.
In the following paragraphs, the transmitter m ay
be unblocked ( transmitting) by closing the CARRIER
START circuit in the case of H ZM relaying, and by
opening the CARRIER START circuit in the case of
K-DAR and GCY relaying.
1 . For D-C pin j ack m easurements with reference
to B-, refer to Table 1 .
2 . For transistor D-C measurements with reference
to B-, refer to Table 2.
3 . For D-C bleeder measurem ent s with reference
to B-, refer to Table 3.
4. For typical RF signal m easurements for re­
ceiv-er, refer to Table 4.
5 . For typical RF
transmitter, refer to Table 5 .
6. Rem oval o f Printed
Flexite st Case.
To remove the printed circuit board, unplug J- 1 5
and J- 1 6 located near t h e output filter. Loo sen t h e
t w o screws inside the case near t h e top. Loosen the
slotted thumb screws at the lower end of the board
and pull these screws out as far as they will extend.
Also remove the receiver coaxial cable plug.
signal m easurements for
Circuit Board from
Pull board down so as to disengag e the terminal s ,
and lift out.
7. Removal of the Output Filter
After the printed board has b een removed, re­
move the screws on the outsid e of the case at the
bottom. Lift out filter and disconnect the coaxial
cable.
8. Receiver Filters
Fig. 1 2 shows typical receiver selectivity curves
in
both RF and IF. If the filters are checked in a test
setup, it is necessary to use an accurate signal g en­
erator or preferably a signal generator and a frequency
counter. H ewlett-Packard Type 400C or equivalent
should be used.
9. Minimum Test Equipment for Installation
a. Milliammeter 0 - 25 rna DC.
b. 60-ohm 5-watt non-inductive re sistor.
c . A-C Vacuum Tube Voltmeter ( VTVM) . Voltage
range 0 . 0 0 3 to 30 volt s , frequency range 60 cycles/
sec to 230-kc, input impedance 7 . 5 megohms.
d. D-C Vacuum Tube Voltmeter ( VTVM)
Volta � e Range :
Input Impedance : 7 . 5 megohms
10. Desirable
Maintenance
a. All item s listed in Sect ions 8 and 9.
b . Signal Generator
Output Voltage:
Frequency Range:
c. Oscillo scop e
d. Ohmmeter
e. Capacitor checker
f. Test harness ( S ee F i g . 19)
0 . 1 5 to 300 volts
Test Equipm ent for Apparatus
up to 8 volts
20-kc to 230-kc
9