Icom IC-751A Instruction Manual page 17

®)PREAMP/ATT (Attenuator) SWITCH
<@MONITOR/MARKER SWITCH
(@MARKER CALIBRATOR
(@MONITOR LEVEL CONTROL
@ANTI-VOX CONTROL
3 - 4 REAR PANEL
This switch selects the RF preamplifier to amplify weak receive
signais or the RF attenuator to prevent overloading of the receiver.
Refer to SECTION 7 - 14 for more information.
This switch turns the MONITOR or MARKER circuit ON or OFF.
• Vary the monitor level with the MONITOR LEVEL CONTROL.
• A calibration marker is generated every 1 0kHz when the circuit is
activated.
This control varies the marker frequency. Use an accurate standard _
frequency source such as radio station WWV /WWVH to calibrate the
marker generator. See SECTION 12 - 3 (2) for more information.
This control changes the audio level of the CW si2etone or SSB
monitor circuit when the MONITOR SWITCH on the top panel is
turned ON. Adjust the contrai for the desired monitor volume.
When using the VOX function, sound from the speaker may cause
unwanted switching of the T/R relay. Adjust this control in con-
junction with the VOX GAIN CONTROL so the T/R relay switches
only from the operator's voice and not from the speaker audio.
@
(@-----RJ.--------~--i::r---,:::r,=n::ri=r,:::r-i=r,::r-s::ri::::n::n::n:::n:n::r-Fl""l=n=n=i-;:::n::fi=r,:::r-i=r,::r--i=i;--zl~-;====H
@---------;4-,!-'
@------;.,.-1-----.
(@)----___,;J...J~~
®------41~~:-,~
®-------'-'-'.....___,,,~
@-----=::-......;,
@-----'-'-..__
(@)ANTENNA CONNECTOR
(@T/R CONTROL JACK [RELAY]
®)
EXTERNAL ALC JACK [ALC]
(@)
RECEIVE ANTENNA OUTPUT
[RECEIVE ANT OUT]
@
@EX@)SP
~
ACC
@
filiill)
.
....1©7
0
@
]I
111
@
0
1~
@
0
~~~
IL_]
Connect a 50 ohm impedance antenna to this connector. The con-
necter mates with a PL-259 plug.
An output signal from this jack controls the transmit/receive switch-
ing of an externat amplifier or transverter.
NOTE: DO NOT attempt to switch greater than 50 volts, 0.5
ampere.
This jack accepts an automatic level control signal from an externat
amplifier or transverter. The ALC voltage must be in the range of
0 volts to -4 volts.
The receive signais from the ANTENNA CONNECTOR pass through
the transmit/receive antenna switching circuit to this jack. Normally,
the receiver IN and OUT jacks are connected together with a jumper.
The ANTENNA OUTPUT JACK is useful when operating with a
separate receiver or an externat preamplifier.
-13-