Readjustment
of the
tuning
and
loading
controls
several
times
will
produce
maximum
output.
·"'-'\rovide
for the extra
power contained
in the AM signal
mudulation
it is necessary to "overcouple"
the output
circuit.
This is necessary to insure an undistorted
output with a minimum
of adjacent channel "bleeding"
(spatter).
Reapply
drive power
and advance the load control
until the
output
meter
drops
perceptably,
(about
15 per
cent
more
rotation).
Readjust the tune control
for maximum output. The
output circuit is now "overcoupled".
If a relative power output
indicator is available (SWR bridge on
forward, etc.) the output signal can be quickly checked to insure
upward modulation.
If the meter does not "flick"
upward on
voice peaks, the load control is improperly set (or the exciter is
not capable of 100 per cent modulation or may have "downward
modulation").
Also seen on output meter.
Automatic
antenna
change
over and
ampl ifier operation
is
provided
for by a special transistorized
input sensing circu it.
Should you desire to hold the amplifier in a "ready"
condition,
but not use it until needed, simply place the XMT-Standby in the
standby
position.
The sensing circuit will be disabled and the
antenna connected to the exciter (transceiver) at all times.
With the XMT-Standby
switch
in the standby
pOSitIOn, the
REC AMP switch
should
be in the OFF position.
This will
prevent the receive
amplifier
loading the transceiver
output.
The amplifier is tuned for FM service in a manner identical to AM
except the load and tune controls are set for maximum output.
Place the function switch in the SSB position. This will connect a
delay circu it to the automatic
relay control
and extend
the
"drop-out"
approximately
one second. This will prevent relay
"chattering"
and erratic operation.
If the exciter (transceiver)
is capable of carrier output
equal to
the peak power of the voice SSB or DSB signal, simply adjust the
tune and load controls
for maximum deflection
of the output
meter while applying carrier.
If the exciter (transceiver)
cannot supply a carrier equal to the
peak power of the voice SSB or DSB signal then the tune and
load controls must be set for maximum output while modulating.
In this case, a modulation
envelope indicator (monitor scope) is
the most reliable method for adjustment of the amplifier.
The delay circuit for SSB prevents "drop-out"
of the automatic
antenna relay between characters.
For operation
on the six meter amateur band It
IS
necessary to
short out four turns from the left hand side as viewed from the
front panel of the Pi-network output co ii, L1. The 100pf silver
mica capacitor across C17 load capacitor, must be removed. Also
remove capacitor C7, 50pf disc ceram ic located across the input
socket of the rear panel.
REMOVE FOR
b
METER
AMATEUR
BAND
OPERATION
IOOpf CAPACITOR
ACCFiOSS
C-17
A portion of the incoming circuit is coupled to the base of 01
sensing transistor. Th is causes 01 to conduct and change the bias
on 02, relay transistor. 02 conducts heavily and closes relay K1.
Relay K1 connects the input signal tQ the cathodes of V1 and V2,
applies plate voltage to V1 and V2, and connects the output
circuit to the antenna.
C18 is the Pi-net tune capacitor and sets the operating frequency
of the amplifier.
C17 is the Pi-net load capacitor and controls the coupling to the
antenna.
For SSB operation,
C22 is added to the relay transistor circuit to
extend the "drop out" time.
An integrated circuit amplifier increases the level of the incoming
signals from the antenna before it is applied to the transceiver.
This amplifier is powered by the XlVlT-Standby switch and the
R EC AMP switch. With the XMT-Standby switch in the XMT
position
the receive amplifier can be switched ON or OFF as
required.
With the switch in the standby position, the receive
amplifier is disabled and the receive amplifier switch should be in
the OFF position (see important note ).
