Advertisement
SECTION
IV
OPERATION
4-1.
AM RECEPTION.
NOTE
The S meter will not give a true indica-
By
Reh Hie Heo ab panel Contaols tochele starting
tion of the IF selectivity because the
Vit
et ari og, oe were
AVC bandwidthis approximately twice
RFGAIN.
0.0.0... 0.0000. 10 (maximum sensitivity).
as wide as the signal bandwidth at the
detector.
AUDIO GAIN... 0.000.000.0040, 2:
found convenient to tune the signal with
the SELECTIVITY
set at 2.5 and then
ANESOF Psi uendioadaycs OFF,
toning mnie sstatton:
FUNCTION
.......0.000004 OFF.
5.
Set the SELECTIVITY control for the desired
.
degree
of selectivity. For standard-hbroad-
SELECHIVITY ............. 2.505.
cast reception (Band 1), the control is nor-
>
mally set to 5 for maximum
fidelity. The
Galen
ee
sone
positions marked
2.5 and 0.5 provide pro-
gressively increasing
steps of selectivity.
2.
Turn
the receiver on by
rotating the FUNC-
Note that as the selectivity of the receiver is
TION control clockwise
fo. AM.
The tuning
increased, the background noise and inter-
dials will light up, indicating the receiveris
forenes- from .adiacont sipnale is reduced:
operative.
Rotate the AUDIO
GAIN control
Too much
selectivity, however, may cause
clockwise for the desired volume level.
excessive
sideband
cutting.
While
side-
band
cutting reduces
fidelity, it may fre-
to center the signal in the IF passband.
IMPORTANT
6.
Use ANL (noise limiter) as noise conditions
The
calibration
on
the main-tuning
Buctare:
(left-hand) dial will be correct only if
the bandspread-tuning
gang is set at
4-2.
EXALTED CARRIER AM RECEPTION.
Dandspread Set. Witis set at any other
in short-wave reception, tranSmission conditions
position,
the
additional
bandspread
frequently are different for waves of slightly dif-
capacity
added
to
the
main-tuning
ferent frequencies.
In voice modulated transmis-
capacity will mis-calibrate the main-
sions
(particularly
AM), which involve sideband
tuning dial.
frequencies
differing
slightly
from
the carrier
frequency,
the carrier and sideband components
4,
Tune to the desired signal with the TUNING
may
not be received in the same relative ampli-
control,
tuning for maximum
clarity. After
the
signal has
been
accurately tuned in,
readjust the AUDIO GAIN control as d
Aa
An
esired,
tudes and phases that were present at the trans-
mitter.
This
effect, known as selective fading,
_#
a4
causes
Severe
distortion
of the signal,
7
Advertisement
