DRAKE TR-4CW - Test Equipment and Alignment; Specific Alignment and Component Checks

DRAKE
However, no attempt should be made to service the
TR—4C unless you are thoroughly familiar with
electronic circuitry and servicing technique. Care
should be taken not to disturb the lead dress in the
TR—4C since several circuits are quite critical in
this regard.
5-6. TEST EQUIPMENT.
Alignment of TR—4C will require the following
equipment:
a. A general coverage receiver capable of receiving
WwVy.
b. An 11 Megohm VTVM.
c.
An
alignment
load
consisting
of
a
1000
Ohm
non-inductive
resistor
in
series
with
a
.005
uF
disc
ceramic
capacitor.
d. A 52 Ohm dummy load.
WARNING
Before receiver alignment is attempted,
the plate and screen power leads of the
amplifier tubes should be disconnected
where they pass turough the partition
under the chassis. Be sure the power is
disconnected before this is attempted, or
serious electrical shock may result.
5-7. ALIGNMENT PROCEDURES.
5-8. CRYSTAL CALIBRATOR. To align the crystal
calibrator perform the following steps:
a. Let the TR—4C warm up for 30 minutes.
b. Preset the XMTR GAIN control fully counter-
clockwise.
. Set the Mode switch to CAL.
d. Tune in WWV on the general coverage receiver
with the BFO off.
e. Connect a wire from the receiver antenna termin-
al to V5 of the TR—4C. Wrap the wire around
the tube a turn or two.
f. Adjust C45, located on top of the TR—4C
chassis, until the calibrator signal is zero beat
with the unmodulated WWV carrier.
Q
5-9. 9.0 MHz OSCILLATOR.
a. Let the TR—4C warm up for 30 minutes.
b. Set the Mode switch in the SSB position.
c. Turn up the Audio Gain control until noise is
audible in the speaker.
d. While switching the SIDEBAND knob back and
forth, adjust C130, located on top of the chassis
near the rear edge, until the pitch of the noise is
the same on both positions.
5-10. INJECTION CRYSTAL OSCILLATOR.
a. Set the VTVM to its lowest DC negative volt
scale and set the pointer to about center scale
with VTVM zero adjust control.
b. Connect the common lead of the VTVM to the
TR—4C
chassis
and
the
DC
lead
to
the
test
point
which is connected to pin 9 of VI.
c. Set BAND switch to 7.0 MHz and adjust L1 for
maximum negative DC voltage.
d. Switch to 21.0 MHz and adjust L5 for maximum
as in Step c.
e. Switch to 29.1 MHz and adjust L2 for maximum
as in Step c.
f. The 28.0, the 28.5 and the 29.1 MHz positions
should have about the same negative voltage.
5-11. VFO ADJUSTMENT.
The permeability tuned VFO was carefully adjusted
at the factory and should require no further align-
ment. If it does not appear to track from one end
of its range to the other, it should be returned to
the factory for realignment. Maximum calibration
error is 1 kHz when calibrated to the nearest 100
kHz point.
5-12. INJECTION COUPLER.
. Tune in a crystal calibrator signal at 7.3 MHz.
b. Connect the alignment load between pin 6 of
V1B and ground and adjust T3 (top) for maxi-
mum S meter reading.
c. Connect the load from pin 9 of V3A and ground
and adjust T3 (bottom) for maximum S meter
reading.
d.
Tune
in
a
crystal
calibrator
signal
at
21.300
MHz
and
repeat
the
procedure
for
T2.
e.
Tune
in
a
crystal
calibrator
signal
at
29.000
MHz
and
repeat
the
above
procedure
for
T1.
Note:
On
T1,
adjust
the
bottom
slug
when
the
load
is
on
pin
6
of
V1B
and
the
top
slug
when
the
load
is on pin 9 on V3A.
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