PS Engineering PMA6000M-S - Manual (Page 23)

PS Engineering
PMA6000 Series Audio Selector Panel and Intercom System
Installation Manual
200-066-0006 Page 3-6 Rev. 6, 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-S, PMA6000M-C, PMA6000M-
S-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 combinations per minute.
The White lamp, labeled "A," is the Airway/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 "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 (6000, 6000S, 6000C, 6000SC)
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.
If using an external marker receiver, the audio input is lower connector, pin 11 (Aux. input).
3.7.3 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
the need for the avionics shop to reduce the sensitivity in the field so as to prevent early detection of the
marker beacons. If your particular installation requires more or less sensitivity, please call the factory for
details on how to adjust the receiver sensitivity in the field.