CIRCUIT DESCRIPTION
Refer to the Schematic (fold-out from Page 87) to identify
the circuit components while reading this section.
POWER
SUPPLY
The power supply uses high voltage transformer. TI, and a
fila~ent and bias transformer, T2. Each transformer has
dualcprimary windings which are connected in parallel for
120 VAC operation, or in series for 240 VAC electric
service. The transformers are protected by two 10 ampere
circuit breakers, wired so they provide appropriate overload
protection for either primary voltage.
The fan motor
is
connected across one of the primary
windings on the high voltage transformer and always
operates on 120 VAC.
is
being used and a higher secondary voltage for
SSB
operation results.
The transformer secondary
is
connected in
a
full-wave,
voltage-doubling circuit. The AC voltage
is
rectified by
diodes, Dl through D14, and
it
is
filtered by
series-connected electrolytic capacitors C10 through C17.
Resistors
R
12 through
R
19
parallel the filter capacitors and
equalize the voltage drop across each capacitor in the series.
They also act to discharge the filter capacitors after the
power switch
is
turned off.
The AC input line
is
by-passed for RF by capacitors C1 and The red-yellow transformer lead
is
connected to the
C2.
junction of capacitors C13 and C14. During the half-cycle
when this lead
is
positive, capacitors C14 through C17 are
charged. During the other half-cycle, the red lead
is
positive
and capacitors C10 through C13 are charged. These two
capacitor strings are in series across the load, and the
HIGH VOLTAGE SUPPLY
voltages of each group add together.
The primary windings of the high voltage transformer, TI,
are tapped, and the six leads are connected to the Mode and
Resistors R1 and R3 are discussed under "Metering
Power switches. Circuits."
When the Mode switch
is
in the CWKune position, the
Chokes RFC 1 and RFC 2 and bypass capacitors C6 and C7
are used to keep RF energy out of the power supply,circuits.
entire portion of each primary winding
is
connected to the
power line. When this switch
is
in the
SSB
position, only the
tapped portion of each primary winding
is
connected to the
The interlock grounds the output of the high voltage supply
-.la-
1;-a
when the top cover of the Amplifier
is
removed. This feature
p1IGI IIIIG.
protects the user against a shock from undi~harged filter
capacitors. The Amplifier must not
be
turned on while the
When the tapped windings (fewer turns) are connected to top cover
is
removed
as
the high voltage supply is
the power source, a higher secondary-to-primary turns ratio
short-circuited under these circumstances.
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