Table of Contents
Advertisement
quencies below 1 10 kc, these c;:tpacitors are 270
mmf. each. For frequencies of 1 10 kc and above, the
capacitors are 140 mmf. each.
C A U T
Turn power OFF before removing filters
10 N
or transist ors , as high t"ransient currents m ay c ause
perm anent damage t o 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
chan g e d ,
there
may be
thes e readings without the overall performanc e being
affected.
Typical voltage and current values are given as
follows. Voltages should be m easured wi t h 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 m easurements with reference
to B-, refer to Table 2.
3. For D-C bleeder measurements 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
R F
transmitter, refer t o Table 5.
6. Rem oval
of
Printed
Flexitest Case.
To rem ove the printed circuit board, unplug J- 1 5
and J- 16 located near t h e output filter. Loosen the
two screws inside the case near the top. Loosen the
slotted thumb screw s 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 .
in
considerable differenc e
signal
m easurements
for
Circuit
Board
from
Pull board down so as to disengage the terminal s ,
and l i ft 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
b ottom. Lift out filter and disconnect the coaxial
cable.
Receiver Filters
8 .
Fi g. 15 shows typical recei ver sel ectivity cur ves
RF
both
and IF. If the filters ar e che ck ed
setup, it is necessar y to use an accurate si gnal gen
erator or preferably a si gnal gen erator and a fre -
quency counter.
9. Minimum Test Equipment for Installati on
a. Milliammeter 0-25
rn a
b.
non-inductive resistor.
60-ohm 5-watt
A-C
Tube Voltmeter ( VTVM) . Voltage
c.
Vacuum
range 0 . 0 0 3 to 30 volt s , frequency range 60 cycles/
sec to 230-k c, input impedance 7 . 5
D-C
Tube Voltmeter ( VTVM)
d.
Vacuum
Volta � e Range:
0 . 1 5
Input Impedance: 7 . 5 megohms
10. Desirable
Test
Maintenance
All
listed
a.
items
in Sections
b.
e
r
tor
Signal G
ne
a
Output Voltage:
up to 8 volts
Frequency Rang e : 20-kc to 230-kc
c. Oscilloscope
d. Ohmmeter
e. Capacitor checker
f. Test har ness (See Fi g. 1 7)
in
a test
DC.
megohm s .
300 volts
to
Equip m ent
for
App aratus
9.
8
and
9
Advertisement
Chapters
Table of Contents
