1 MODEL 4OO TRANSCEIVER
C. Operation
(Cont)
(i)
Rotate PA Load Coarse to
position
6.
(j
)
Rotate Bandswitch on
Fre
-
quency
Control Unit to
desired band,
(k)
Set !'requency Control Unit
tuning dial to desired operat-
ing f!equency.
(l
)
Set R!. Gain Contlol to
approximately
3
o'clock
position.
3. Rotate the Function
Switch
clock-
wise to the REC
position.
4. Care{ully adju6t the PA Glid and
th€ PA Plate controls for maxi-
rnudr receive!
noi3e.
Note:
The
PA Grid Control
resonates
the
transmitter driver stages and the
receive! RF amplifie!
plate
cilcuit.
The PA Plate ard PA Load con-
trols adjust the input and output
capacitors
in the transmitter
power
arnplifier
final
plate
circuit, as
well as the receiver RF ahplilier
grid
circuit.
Prope r adju6tment
of these controls in the receive
position
will re6ult in approximately
resonant
conditions in the trans-
rnitter stage6.
RECEIVER
TUNING
-
IMPORTANT,
READ CAREFULLY.
Precise
tuning of
a Bingle Bideband
signal
is
very
important. Do not be
€atisfied
to merely tune unti.l the voice
can be understood, but take the extra
care of settiDg the dial to the exact
€pot
where
the
voice
sounds natural.
Above all,
avoid the habit of tuning so
that
the voice
is
pitched
higher than
norrnal.
This is an untortunate
habit
practiced by
quite
a
nuhber ot oPera-
tois, The following
points help to
explain
the effects o{ rnistuning:
I. If
you tune so the received voice 1s
higher than normal
pitch,
you will
then transmit ofI frequency, and
your Yirce will sound lower than
nor't[.]
pitch
to the other station,
He
wlll
probably
retune hi8 dial to
mak€
/,rrr
sound right. If
fou
keep
this up,
you'Il gladoally
waltz one
another across the
band,
If both
of
you
are rnistuning to an unnatural
higher
pitch,
your11 waltz
across
the
band twice as fast.
(And
someone
will
no
doubt
be
accused of fre-
quency
drift),
2.
Mistuniog !esult€ in
serious har-
.
monic distortion on
the
voice, and
ghould
be quite noticeable to the
average ear.
Some
will claim that
if
they
donrt know how the other
personrs
voice actually sounds,
they
canrt tune hiln in
propelly,
but this
i6 not true. With a little
practice,
it wiU be Iailly easy to tell. Sorne
voices are relatively rich in
ha.-
monics, and
ale easier to tune iD
rhan a
person
v,/ith a
r'Ilat"
voice.
AIso, a
transmitter \rhich is being
operated
properly
with low diBtor-
tion will be eaEier to
tune
in
than
one which i€ being
over-driven and
is
generating excessive distortion,
There is no lnistaking
when you
have a station tuned right on the
nose,
It wil.l
sound
ju6t
like
I'AM, r'
so to speak. Mainly, avoid
the
habit
of tuning 6o everyone sounds
higher than rormal
pitch, or like
Donald Duck. This i6 incorrect,
unneceaaary and sounds
terrible.
3. A vernier
control for receive fre-
quency, sometime6 reterred to as
!'incremental
tuning,rt
is not
avail-
able on the S\ran 400.
Such
a
device
is not necessary if
proper
tuning
habits are
exercised.
t3
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