Heathkit RA-1 - Front End Alignment Procedure

Teathect }} 29
DAYSTROM
( } Connect the positive or ‘hot' lead of the signal generator te the AE terminal on rear of chassis and earth lead
to E, If convenient this connection may be made co-axially to the co-awx input socket,
{ } Turn all the equipment on and let it warm up for approximately 30 minutes to stabilise all circuits.
{ ) Switch the AC meter to a range between | and 3 volts and set the generator for a modulated high output level.
The output of the generator should be reduced as the alignment procedure i increases the sensitivity of the re-
ceiver, to keep the meter readings at approximately | volt. ~
( )} Unscrew core of L19 four turns.
— —
Start alignment of the IF transformers by adjusting the signal generator to approximately 1621 Ke/s for maxi-
mum indication on the meter. The generator reading at this time may be slightly above or below 1621 Ke/s IF
frequency.
( }) Adjust the bottom slug of the transformer IFC for maximum meter indication. NOTE; Cores used in the trans -
formers permit the alignment tool to pass through from top to bottom core thus enabling all alignment to be
carried out from the top of the receiver. Now adjust top core of IFC for maximum indication. Proceed to
transformers IFB and IFA and make a similar adjustment.
( } Swing signal generator for a maximum meter indication, then repeat the IF transformer adjustment as in the
preceding step. (Two peaks may be observed indicating each crpatal resonance. Set generator to mid-point
P 5 P- 4 P ¥ 6 ¥ & B
for final alignment. }
( ) Repeat the entire procedure as in the above two steps until further adjustment does not cause an increase in
meter reading.
{ )
Place
the
BFO
switchto
the
ON
positicn
and
ensure
that
mode
switch
is
in
the
O
position.
Turn
the
modula-
tion
switch
on
the
signal generator
to off,
Adjust
the
core
in
the
BFO
coil
until
you
obtain
a
zero
beat.
,
Switch
the
mode
switch
to
USB
and
then
to
LSB
which
should
produce
an
equal
heterodyned
pitched
note
in
either
q
yned
p
pogition.
If
the
tone
is not
of
the
same
frequency,
re-adjust
the
BF
coil.
—
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2 m
jae
>
a
2
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+
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snerator on with high level output.
ust core o or minimum meter reading.
Adjust f£L19f ini t di
{ } This completes the alignment of the IF stages in your receiver. Disconnect the test equipment.
FRONT END ALIGNMENT
In order to obtain optimum results from the receiver, the coil pack should be aligned with an accurate amplitude
modulated
RF
signal
generator
and
anAC
voltmeter.
It
is
very
important
that
the
signal
generator
be
very
accurate.
Therefore,
the
generator
should
be
calibrated
against
a
crystal
calibrator
or
a
receiver
of
known
accuracy.
If
the
Heathkit
Model
CL-1]
Crystal
Calibrator
has
been
purchased,
it
should
be
assembled
at
this
time
and
used
to
cali-
brate
the
signal
source.
When
performing
the
following
steps,
bear
in
mind
that
the
coil
pack
has
been
pre-set
by
the
manufacturer,
but
due
to
differences
in
valves
and
assembly
techniques,
some
re-alignment
may
be
necessary
in
order
to
obtain
optimurn
results.
Usually
this
adjustment
will
consist
of
not
more
than
$
turn
of
coil
cores
or
a
slight
movement
of
associa-
ted
capacitors.
( ) Set all panei controls as follows: -
AF GAIN Maximum RF GAIN Maximum
BFO mode Oo TUNING As chart
BAND As chart BFO Off
NL MIN AVC OFF
CAL ADI 12 o'clock ANT TRIM 1Z o'clock
{ } Connect the RF signal generater to the antenna terminals or co-axial socket
BLQOUCESTER