11.
12.
For CW reception on the
.
4 position the signal is tuned for most
pleasing note with the
frequency knob and is then peaked with the
PASSBAND tuning knob.
You can
then tune other stations without
changing the
PASSBAND tuning knob setting. The audio frequency
at maximum signal strength will be
correct.
PHONE JACK - A PHONE JACK is provided on the front of the R-4A for
private listening when desired. The jack automatically mutes the
speaker output when headphones are plugged in. While the headphone
impedance is not critical (adequate output is available for most com-
mercially available phones) more output is obtained on lower impedance
phones . We recommend a good set of 600 ohm phones, such as the
Trimm type 56 - 06.
S-METER - The S-METER indicates relative signal strength of the re-
ceived signal. It is calibrated in S-units from S-l to S-9 and DB over
S-9. Each S-unit equals about 5 DB and S-9 is about 30 microvolts
at the ANT terminal.
B. REAR CONTROLS & JACKS
1.
2 .
3 .
4 .
5.
6.
INJ. JACK - The INJ. jack provides a means of coupling the premixer
system of the R-4A to the T4 or T4X transmitters so that transceive
operation with these units can be obtained.
SPEAKER JACK - The SPEAKER JACK on the rear of the chassis
is
for the
connection of a 4 ohm speaker such as our MS-4.
MUTE JACK - The MUTE JACK is for externally muting and unmuting the
receiver. The receiver is muted when the FUNCTION switch is in the
EXT-MUTE,
N.
B., and CAL positions and when the center conductor of
this jack is open from ground. Shorting the center conductor to ground
returns the receiver to the receive condition.
ANTI-VOX JACK - High impedance audio is brought out the ANTI-VOX
JACK for use in energizing the ANTI-VOX circuit of a transmitter used
with the unit such as our T-4 and T-4X.
ANTENNA JACK - The ANTENNA JACK provides a means for connecting
the R-4A to an antenna. The input impedance at this point is approxi-
mately 52 ohms and can be used with antennas having impedances
between 50 and 75 ohms.
POWER SOCKET - A POWER SOCKET is provided on the rear of the R-4A
for operating external accessories. This plug mates with a Cinch Type
5AB2 connector. Maximum load is 6.3 VAC @
.75
amp and +150 VDC
@ 30 ma.
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