Heathkit RA-1 - SSB Signal Reception Procedure; Antenna Connection and Usage; Receiver Alignment; IF Transformer Alignment Procedure

28
{ } Rotate the TUNING control until a CW station is located. See Step 10, Page 29 for BFO adjustment.
{ ) Adjust RF GAIN control for comfortable listening level.
NOTE:
If
interfering
signals
are
present,
it
is,
on
occasions,
an
advantage
to
switch
to
either
USB
or
LSB
to
re-
move unwanted signals and listen under SINGLE SIGNAL condition.
SSB OPERATION
For
55B
reception,
set
the
controls
as
explained
for
CW
operation
with
the
following
exception
-
select
the
wanted
sideband
using
MODE
switch.
Tune
into
LSB
signals
from
HF
to
LF
direction
on
the
tuning
scale
and
LF
to
HF
for
USB
signals.
As
with
CW
reception,
the
listening
level
should
be
adjusted
with
the
RF
GAIN
control,
with
the
AF
GAIN control at or near maximum. AVC, if preferred, may be left ON permitting some AGC control.
NOTE:
It
is
possible
that
due
to
wiring
variations,
the
BFO
injection
voltage
may
require
adjustment.
This
can
be
-
achieved
by
altering
R35
{located
between
tagstrip
TB2
and
V4
pin
1)
in
value
between
JMADKN
and
go
Ko
{these
resistors
are
included
in
the
kit},
To
check
for
correct
injection
voltage,
tune
to
a
sideband
signal
on
the
20
metre
band
without
BFO
switched
on.
Now
switch
on
BFO.
If
the
station
strength
decreases
BFO
injection
is
too
great
and
R35
should
be
changed
to
a
higher
value.
If,
however,
the
signal
can
only
be
resolved
with
considerable
re-
duction
of
the
RF
GAIN
control,
then
BFO
injection
is
insufficient
and
R35
ahould
be
changed
to
a
lower
value.
The
BFO must be re-adjusted as outlined in the IF ALIGNMENT section of the Manual.
If
the
receiver
is
used
for
mobile
or
portable
use,
power
supplies
as
stated,
should
be
connected
to
the
socket
at
the
rear
of
the
chassis.
When
used
with
a
12-l4v
supply
for
the
heaters,
a
voltage
dropping
resistor
of
2
ohms
25 watts may be connected between TH] and TH3, or otherwise external reduction must be made.
ANTENNA
The Receiver will operate using a long wire attached to the antenna terminal, however, for the best results, the
antenna should have an impedance of 50 to 1002. This could be a dipole type antenna and constructed for the band
that you desire to receive. Naturally, if this Receiver is to be used in conjunction with a transmitter, the trans -
mitting antenna should also be used for reception, For this type of operation, the antenna must be switched from
the transmitter to the Receiver. This arrangement would preferably have the input connection to the Receiver
earthed down during 'transmit' periods to avoid accidental RF input to the Receiver, If you wish to construct a di-
pole type of antenna, we suggest that you refer to the R.S.G.B. Radio Amateurs Handbook, available from the
Society's Headquarters.
RECEIVER ALIGNMENT
The IF transformers and coil pack have been pre-aligned to factory standards, therefore, no further adjustment
should be necessary.
Those without instruments are strongly advised not to alter the trimmers on the coil pack, but the IF alignment can
be checked by tuning to a weak station, or noise, and adjusting the trimmers on the IF coils for maximum output.
Be careful not to ne ef the cores top far in the eu and s0 align on the ‘inner’ peak. w fA
cone frame formed VE athnwr OW my pewk
The following oe af procedure is ee ed for those who wish to check the alignment and have the neces-
sary test equipment.
Refer to Pictorial 3 for the follawing steps:
IF _ TRANSFORMER ALIGNMENT
Equipment Required: An amplitude modulated RF signal generator and an AC voltmeter,
{ ) Set all panel controls as follows:-
AF GAIN 12 o'clock RF GAIN Maximum clockwise
BFO mode o BAND 80 metres
TUNING 3.6 Mc/s NL MIN
AVC OFF BFO OFF
( ) Connect one lead of the AC voltmeter to the 3 OHM terminal and the other lead to the COMM terminal with the
speaker still connected.
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