III CONTROL FUNCTIONS
A. FRONT
1.
MAIN TUNING
-
The MAIN
TUNING
knob of the R-4A determines the
frequency on which you are receiving. The vernier skirt around this
knob is calibrated in KC’s from 0 to 25. The main dial is calibrated
in five KC divisions and has two scale
S
.
Use the 0 to
.500
scale
for bands 7.000-7.500, 14.000-14.500, 21.000-21.500, etc.; use
the
.500
to 1.000 scale for bands 1.500-2.000,
3.500-4.000,
28.500-
29.000, etc. The small red knob just to the right of the dial scale
is for adjusting the position of the indicator line for calibrating the
main dial. The knob skirt is also adjustable by pushing it in slightly
and rotating it in the desired direction while holding the main tuning
knob stationary.
2.
BAND
-
The BAND control is a six position switch used to select the
amateur band desired or to switch the RF circuits to the correct tuning
range when tuning accessory frequency ranges.
The frequency range
which may be tuned for each setting of the band switch control is
given on the chart on page 16.
3.
XTAL
-
The XTAL switch is an eleven position switch used to determine
which crystal socket will be inserted in the circuit. When it is in the
normal position,
crystal selection is accomplished by means of the
band switch (with the exception of the 1.5 setting). When this switch
is set on any of the other positions 1 through 10, the crystal inserted
in the corresponding crystal socket will be inserted in the circuit for
accessory band operation.
The BAND switch must then be set in ac-
cordance with the information given on the crystal frequency chart
for reception of the frequency desired.
4.
PRESELECTOR
-
The PRESELECTOR control permeability-tunes the antenna,
RF, and premixer coupling coils to the desired frequency. The logging
scale on this control is calibrated from 0 to 10 with markings showing
the correct settings for the 160 through 10 meter amateur bands.
5.
FUNCTION
-
The FUNCTION switch is a six position switch used to
select the method of operating the R-4A.
When in the OFF position the power transformer primary is opened,
thus turning the unit off.
When in the STBY position, the power
is connected, thus allowing the filament and B+ to operate but the
receiver is muted regardless of external connection. When in the
ON position,
the receiver is unmuted regardless of external muting
connection.
When in the EXT-MUTE POSITION, the receiver is
muted or unmuted depending upon whether or not the mute connection
on the rear of the chassis is grounded,
thus permitting external control
-9-
(66 pages)
(472 pages)
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