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PMA7000B Pilot Guide
1.4 Audio Selector (All models)
Receiver audio is selected through seven momentary, push-button, backlit
switches. You will always hear the audio from the transceiver that is se-
lected for transmit.
The users can identify which receivers are selected by noting which of the
green switch LEDs are illuminated. Push buttons labeled Nav 1, Nav 2,
MKR (Marker), AUX (auxiliary), and SPR (Speaker) are "momentary type
switches. When one of these buttons is pressed, it's active, and the LED will
illuminate. Press the switch again and it be in the "off" position and remove
that receiver from the audio.
If the aircraft is equipped with a DME or ADF, these audio sources can be
selected with the AUX button.
1.4.1 Speaker Amplifier
The "SPR" in the push-button section stands for speaker. This switch will
place all selected audio on the cockpit speaker when this
switch is activated. NOTE: Except for the unswitched
audio, the speaker amplifier is not active in the "Split
Mode."
Unswitched audio, (autopilot disconnect, altimeter warn-
ing, etc.) will come through the speaker regardless of the
speaker button position.
1.4.1.1 Public Address Function
To access PA function, an external switch must be installed, and activated.
This places the pilot microphone on the speaker output when the PTT is
pushed. The copilot can continue to use the selected com radio.
We recommend that the switch transfer the audio from the cockpit speaker
to a cabin speaker for public address. This will prevent feedback.
1.4.2 Key “Click”
The PMA7000B is equipped with a “click” function that provides an aural
feedback to the user in addition to the tactile button push. This sound can
be enabled or disabled by simultaneously holding the COM 1 and COM 2
buttons in for at least 5 seconds. Any person hearing the radios will also
hear the key click.
Allow at least 20 seconds between turning the key click on and off.
1.5 Split Mode
The split mode can be activated at any time by pressing the desired combi-
nation of XMT buttons. For instance, to activate a Com 1/Com 2 split, press
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PMA7000B Pilot Guide
202-780-0001
discrete switches mounted adjacent to the headset jacks. When Com 3 is
active in the duplex mode, the TX button will blink about twice as fast as
the normal transmit rate.
When the intercom is in ALL mode, the pilot can speak on the phone only
if the Com 3 is selected for transmit (Com 3 Xmt button activated). All
intercom positions will hear the telephone conversation. If any passenger
places his or her switch into the “off-hook” position all passengers will also
be heard on the phone. All hear selected audio. Com 1 audio is automati-
cally heard in the headsets. The pilot and copilot will have transmit capabil-
ity on the other selected transceiver Com 1 or 2, simply by using their re-
spective PTT switch.
In CREW mode, the pilot and copilot may use the telephone, with their
respective hook switch (the pilot selects Com 3 on the Xmt selector). Any
passenger who places their switch into the off-hook position will also have
access to the phone, and all four passengers will hear the conversation.
In ISO intercom mode, when the PMA7000B is in the Com 3 mode, the
pilot position is in the "Phone Booth." He will also have access to Com 1
or 2, and will transmit on that radio using the PTT. All selected audio is
provided. If any other passenger goes “off hook” they will hear the phone.
Note: Because the telephone uses an intercom circuit, all stations on
that circuit will lose intercom capability when the telephone is in use.
1.8 Marker Beacon
The optional Marker Beacon Receiver uses visual and audio indicators to
alert you when the aircraft passes over a 75 MHz transmitter.
The Blue lamp, labeled "O," is the Outer Marker lamp and has an associ-
ated 400-Hertz 'dash' tone. The lamp
and tone will be keyed at a rate of two
tones/flashes per second when the air-
craft is in the range of the Outer
Marker Beacon.
The Amber lamp, labeled "M," is the Middle Marker lamp and is coupled
with a 1300-Hertz tone. It is keyed alternately with short 'dot' and long
'dash' bursts at 95 combinations per minute.
The White lamp, labeled "I," is the Inner marker and has a 3000-Hertz 'dot'
tone. The lamp and tone will be keyed at a rate of six times per second.
The audio from the Marker Beacon Receiver can be heard by selecting the
"MKR" push-button switch. To adjust the volume level, there is a service
adjustment located on the top of the unit.
A three-position switch is used to set the receiver sensitivity and to test the
indicator lamps. Use "HI" sensitivity initially. This allows you to hear the
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