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OUTPUT IMPEDANCE: For high impc<lance phones, or
loudspeaker
voice
coil.
·
POWER OUTPUT: 350
milliwatts
maximum, 225 milliwatts undistort,d.
SENSITIVITY FOR 10 MILLI\VATTS OUTPUT: 5 microvolts average.
SELECTIVITY
JN KC OFF RESONANCE:
Avmges
19 kc at
60
db down.
IMAGE ATTENUATION: Averages 65
db.
SIGNAL-TO-NOISE AT MAXIMUM SENSITIVITY: Averages 8 db.
1-F INTERFERENCE RA TIO:
Averages -85db.
A.V.C.: Holds
the output level
within
;t;
!}db
when
the input
varies 80 db.
AUDIO CIIARACTERJSTICS: Within 2
db
from 250
to 1500
cycles
Down
10
db at 100 and
2500
cyclos.
MODULATION CAPABILITY:
85~
.
.
The
transmitter
section
of
the
unit
is
loa.ted on the
right
hand
end
of
,he chassis.
Its
cirruit
emplo)'S four valves which perform
functions as
follows:
The crystal O$Cillator
stage employs
a
type
IH◄G
valve.
One
of the
three crystals
is
selecte<I by
the
rotary •"·itch,
whose pine!
control
is
deSJgnated CHANNEL.
The
cryml s,lected connects
to the IH4G in
a
standard grid-to-ground O$Cillator
circuit. The
plate circuit of this valve is
tune<!
by
a
tank
circuit consisting of an
ind uctance and one of three variable
,ir condtnstrs which
art also
switched
by
the CHANNEL switch. Three
tank circuits art
thus ,ffectively ffllploycd so that each
tan~
can
be
pre-tune<!
to 1h,
frtqu,ncy
of
th,
associated cryst•I. These oscillator
lank
condenscu,
CH, C35 and
C36, are
located in
a row
in the
right hand
end
of
the
chassis
under
their
respcctivt crystal socktts.
The
inductance
in the
oscillator tank circuit
is tappc<I for
connection
·o
the I
80
volt supply
so
that double-ended
tank opccat1on
i,
rrovidcd. One
-nd
of
this•
tank
JS
connected
to the p>rallel control
grids
o
a
type 1)6G
?"wer
amplifier valve
through • coupling condens<r,
CJ2, while the
other
~nd
1s connected
through the
ad1ustable air condens<r,
CH, to apply
out-of-
•~ast
neutralizing
voltage to't~e
paralleled
plates of
the
p·• inductance.
•
The
plates of the 1)6G
p-a
valve
are supplied with 180 volts
d-c through
he
secondary winding
of the
modulator
transformer
and throu8h an ,.f
hoke, while
the
,.f voltage
generated
by
the'
valve is
fed
through
a
d-c
,locking condenser,
C29,
to an output tuning circuit
consisting
of
a
tapped
:oil ,nJ \'atiable condense,. The taps on the coil arc connected to a 17 point
,ot«y
tap switch
mounted
on the
front
p•nel and dcsignattd COUPLING
The variable condenser is
fitted
with
a
vernier drive
and
locatts
beside the
oil.
These two
compancnts
arc
connected
to
form what
is
commonly kno•:n
u a.n "L"
nctwotk in which the antenna
is connected as a
series element
2thcr
than
a
shunt
element
of the output tank. The main advantage of this
1pe of circuit
is its
simplicity, since both
the
p•a pl•te and antenna circwts
re tuned simultaneously.
The
const,nts
of
this
circuit
arc
chosen
to
allow the
ransmitter
10
feed antenn•e
of
ltngth
between that
of the
rod
and
a
wire
ntennae
one quarter
wavelength long.
as
may
be used
in scmi-6xcd
station
en·icc.
·
6
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