Operating instructions
NOTES:
I UNLESS
OTI-]ERlIISE
INDICATED:
VALUES
ARE
IN
MICROMICROFARAOS.
Rrl
too K
c24
ALL
CAPACITANCE
K
=
l,0OO
OHM
S
UH
=
MICROHENRYS
UF
.
MICROFARADS
SWITCH
SECTION
DES!GNATED
ItO.I
s2
sHOWN tN
C.w. POStTt0N.
sw|lcH
sEcTtoNs,
AS
VIEWED,
ROTATE
COUNTERCLOCKWISE.
8.F.O
OUTPUT TO
2D l'F Al,tPLlFrER
v5
(PtN
6)
3.
6.
7,
IS
NEAREST
ÎHE
KNOB
END
LOW A.F
B.F. O.
v7
lR5
AMPLIFIER
2
I
:;;
I
|
:Ei,
Ln
ù
Y)
'_f_
-
a
J'
SECT
3
REAR
coil,
ancÌ
parasitic
sllppressor L3.
The l0K-ohm
resistor
and R13 form
a voltage divider.
C26
pÌaces
the oscillator
plate
return
at r-f
ground
potential.
d.
The
harmonic frequencies
of the oscillator
are radiated
ancl
picked
r"rp
by the first r-f
amp-
lifier. The
signals are
amplifiecl through
the
receiver
and beat u'ith
the bfo to
proclnce
a
difference frequency
to be detected.
This de-
velops
a beat
note
every
200 kc,
for calibration
of the receiver
on bands 1. 2. and 3.
\Vhen
BAND
SW.
srvitch
51
is
in
the
band 4
position.
the
harmonic frequencies
are injected into
the
gricl
circuit of r-f amplifler
tube V1 through
section
2, front, of slvitch
51,
capacitor
C54,
and section 3,
rear,
of
BAND
SW. switch
Si.
I'apacitor
C3
couples the signals from the
tuned
'ricl
circuit to
the
grid
(pin
1)
of Vl.
e. In
all
positions
of
PHN.-C.\Y.-NET-CAL.
50
TM 295-31
srvitch
32,
except
CAL., the oscillator
plate
and
i:aciiating
elemetrt is
grounded
for
rf through
C48 and section 1,
front,
of 52.
64.
PHN.
Operotion
(fig.
32)
In the PHN.
position
of
PHN.-C.W.-NET-
CAL. srvitch
52, the receir.'er is
operative for
voice
signals. The
bfo and the crystal
calibra-
tion oscillator
circuits
are
inoperative.
Capaci-
tor C46 is a lorv-impedance
path
to
ground
for
the bfo signal,
ancl capacitor
C48
is
a low-im-
pedance path
to
ground
for the cr1'stal
calibra-
tion osciliator
signal. In this mode
of operation,
C46
places
the screen
grid
(bfo
plate)
at, a-f
ground
potential,
and C48
is
used as an r-f
bypass for
the screen
grid (calibration
oscil-
lator
plate)
of V5.
The
control
grid
of V5
also
is
grounded.
Fi,gure
3(t. Rodio Receíuer
R-174lURR,bf
o,
ìuncilottal
sch.ematic.
AGO 313A'