PS Engineering PMA7000B Pilot’s Guide - Manual (Page 9)

9 PMA7000B Pilot Guide R6 202-780-0001
Marker Beacon
The Marker Beacon Receiver (if
equipped) 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 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 "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
outer marker beacon about a mile out. Then select the “LO” sensitivity to
give you a more accurate location of the Outer Marker. The momentary
down switch position is marker test, labeled "T/M" and illuminates all
three lamps simultaneously to assure the lamps (internal and external) are
in working order. TST does not activate MM sense output.
Pressing the marker mode select down (to “T/M”) will cause the marker
audio to mute for that beacon. The next beacon received will re-activate the
audio.