Heathkit GR-54 - BFO Adjustment; Control Configuration; Zero Beat Procedure

Page 42
( ) Turn the BAND switch to E, and adjust the
MAIN TUNING so the dial pointer is at 15
mec, NOTE: If stations WWV or WWVH
: cannot be found near 15 mc, tune toa signal
on the Amateur Band (14,0 me to 14.35 mc)
or on the Citizens Band (26.965 me to
27.710mc),
(
—
Adjust coil #40-654 until the correct fre-
quency is heard,
a 5
r%
%)
&
&
a
( } Tune in a station near 13 m
eoil #40640 for 2 maximum
ing,
( } Tune in a station near 18 mc and adjust
coil #40-658 for a maximum meter reading...
Set the Receiver front panel controls as follows:
BANDSPREAD, ,... -adjust for a 5 indication
on the Bandspread dial,
AF GAIN ........ adjust as necessary during
alienment
alignment,
RF GAIN, . 2.0 2 ce eeeee full clockwise,
MODE , .ccccecvccscccccsececesee AM,
ANT
TRIM,
......
ceeee.
full
clockwise,
BAND ows sesecsscssesecscs tects Be
Braver merrarrsate aanaan
MAIN TUNING, .....adjustas necessa
ANL, -c ccc creer c cess eases esee OFF.
OPR . cece ccnccccccccccccecee REC,
( ) Tune in a strong station that will give a
meter reading above 3,
(
ed
Slowly adjust the Bandspread dial pointer
¢,
+ .
for
a
maximum
meter
reading.
Then
adjust
the RF Gain contro] for a meter reading of
3. NOTE: The meter needle will fluctuate
around 3 slightly because of the varying
amplitude of the voices or music being re-~
ceived,
HEATHEIT
( } Now adjust the Bandspread dial pointer
towards SET until a meter reading of 2,5is
obtained,
( } Turn the MODE switch to USB. A contin-
uous tone should be heard, If itis not heard,
adjust coil L18, This coil which is located
on the IF-audio circuit board should not have
to be adjusted more than one turn in either
direction before the tone is heard,
NOTE: In the following steps, coil L18 will be
adjusted for a zero beat, Zero beat can be de-
fined in the following way: As the coilis adjusted,
the tone you hear decreases from a high toa
gradually lower pitch, until no tone is heard at
all, This point where no tone is heard is called
the zero beat point, if you continue to adjust the
coil in the same direction, the tone will gradually
increase from a low to a high pitch again,
( } Adjust coil L18 as close as possible to the
zero beat point,
( ) Turn the MODE switch to AM and adjust the
Bandspread dial pointer slowly towards 10
eT
until a meter reading of 2,5 is obtained,
NOTE: As the Bandspread is adjusted to-
wards 10 the meter response is proportion-
- al to the crystal filter response, During
these adjustments, the BFO is set, first on
one side of the crystal filter response siope,
and then on the other side. When the Mode
Send § bint sa .
switch is set in the LSBposition, capacitors
C48 and C49 are switched into the BFO
circuitry to move the BFO frequency to the
other side of the slope.
( } Turn the MODE switch to LSB. A tone
should be heard,
( } Turn the threaded shaft of the 1-10 puf
trimmer capacitor until zero beat is reach-
ed,
This completes the alignment of the Receiver,