PS Engineering PMA6000M-C Installation Manual - Manual (Page 20)

PS Engineering
PMA6000 Series Audio Selector Panel and Intercom System
Installation Manual
200-066-0100 Page 3-5 Rev. 1, March 2005
The recorder function is automatic. Pressing the momentary switch will cause the last message to play (in-
coming radio and transmit sidetone). This will be heard in the pilot headset only. To hear older messages,
push the playback button repeatedly to “back up” the recorder, until the desired message is heard.
The recorder is a continuous loop, and newest ones will overwrite the oldest messages.
The IRS has an internal squelch that prevents storing ‘dead’ air. A radio signal of more than 1 VRMS is
needed to trigger the IRS. Therefore, if the IRS does not seem to be recording, increase the aircraft radio
volume slightly.
3.7 Marker Beacon (PMA6000M, PMA6000M-C)
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 associated 400-Hertz
'dash' tone. The lamp and tone will be keyed at a rate of two tones/flashes per second
when the aircraft 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 combina-
tions per minute.
The White lamp, labeled "I," is the Inner marker/Airway 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 "M" push-button switch. To
adjust the volume level, there is a service adjustment located on the top of the unit. See Section 2.5
A 3-position switch is used to set the receiver sensitivity and to test the indicator lamps. Use "H IGH " sensi-
tivity initially. This allows you to hear the outer marker beacon about a mile out. Then select the “L OW ”
sensitivity to give you a more accurate location of the Outer Marker. The momentary down switch position
is labeled "T
EST " and illuminates all three lamps simultaneously to assure the lamps are in working order.
Upon first application of power to the unit, the Marker enters a self test mode. The flickering blue marker
light indicates a test in process. If the test continues for more than 10 seconds, or the lamps do not extin-
guish, return the unit for service.
3.7.1 Middle Marker Sense
A Middle Marker sense output signal is available to automatically reduce the autopilot sensitivity after the
aircraft has passed over the Middle Marker. This function will not operate during the test mode. This out-
put will go to +4.75 VDC (
± 0.25 VDC) when a valid Middle Marker signal is received.
3.7.2 External Marker Lights (6000M, 6000MC)
For installations that require external marker beacon lights, there are three outputs that can drive 12 Volt
lamps only. The external output lamps are driven high (+9 VDC
±0.5 VDC) when active. Maximum
source current per lamp is 125 mA.
3.7.3 External Marker Audio Input (6000, 6000C)
If using an external marker receiver, the audio input is lower connector, pin 11 (Aux. input). This will ap-
pear at the audio when the M button is pressed.
3.7.4 Receiver Sensitivity
Although the PMA6000M meets FAA TSO-C35d sensitivity specifications, the sensitivity of the receiver
has been adjusted to meet real world requirements (150
µV and 1400µV Soft). This will usually eliminate
Figure 3-4
Marker Beacon