MuseChaser
Pattern Altitude
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- Feb 23, 2019
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MuseChaser
Tearing what few hairs I have left out trying to figure this out..
Removed a Narco AT150 transponder, and replacing it with a Stratus ESG. Existing working altitude encoder is a Narco AR850. All quotes and pin numbers below were taken from the AT150, AR850, and ESG manuals, and connectons between the AT150 and AR850 were verified when the AT150 and original harness were removed. Currently building the new harness; the parallel data connections are obvious and no problem.
Here's the specific questions...
1. AR850 Pin 15, "Power Ground," was previously connected to AT150 Pin 2 "Ground." Should it now be connected to...
A. Directly to an aircraft ground point.
B. ESG Pin 37 "Altitude Common (GND)"
C. ESG Pin 1 or 20 "Aircraft Ground" via a jumper/splice between those two. The ESG installation manual specifies "A minimum of 2 ground pins should be tied, and the wiring diagram shows pins 1 and 20 jumpered/spliced with the note "From splice to unit, wire length should not exceed 6 inches." Pin 18 is also listed as "Aux Ground."
2. AR850 Pin 14, "Aircraft Power," was previously connected to AT150 pin 18 "Digitizer Power." Should it now be connected to...
A. ESG pin 2/21 "Aircraft Power" via jumper/splice between those two terminals. The ESG wiring diagram shows those two terminals jumped and connected to aircraft power via a 5A breaker, with the same "6 inch max" from splice to unit caveat.
B. Aircraft Power via it's own new 2A breaker.
3. AR850 Pin 6 "Enable" was previously attached to AT150 Pin 5 "Digitizer Common." Should it now be connected to...
A. ESG pin 37 "Altitude Common."
B. Aircraft Ground.
C. External switch to ground.
I'm not really sure which box (ESG or AR850) is responsible for enabling the Mode C/altitude reporting output. The AR850 manual states..
"Activating the AR850 requires that a ground be applied to P101-6,
the ENABLE input, only when the transponder is placed in the
altitude mode. Normally the transponder would be the ground
source....
If the transponder's internal ENABLE source is a permanent ground
and not altitude mode controlled, the AR850 will be permanently
enabled. When the altitude reporter is permanently enabled, the
companion transponder must have additional internal circuitry
designed to inhibit the transmission of altitude information when
it is operating in other than the altitude mode. If the
transponder cannot meet this requirement, the AR850 ENABLE input
must be controlled by a panel mounted switch."
DOES the ESG handle the Mode A/C/S switching, and AR850 Pin 6 can just be grounded keeping the AR850 active all of the time, or does attaching it to ESG Pin 7 "Altitude Common" take care of this?
Heeellllllppppp......and thank you.
Removed a Narco AT150 transponder, and replacing it with a Stratus ESG. Existing working altitude encoder is a Narco AR850. All quotes and pin numbers below were taken from the AT150, AR850, and ESG manuals, and connectons between the AT150 and AR850 were verified when the AT150 and original harness were removed. Currently building the new harness; the parallel data connections are obvious and no problem.
Here's the specific questions...
1. AR850 Pin 15, "Power Ground," was previously connected to AT150 Pin 2 "Ground." Should it now be connected to...
A. Directly to an aircraft ground point.
B. ESG Pin 37 "Altitude Common (GND)"
C. ESG Pin 1 or 20 "Aircraft Ground" via a jumper/splice between those two. The ESG installation manual specifies "A minimum of 2 ground pins should be tied, and the wiring diagram shows pins 1 and 20 jumpered/spliced with the note "From splice to unit, wire length should not exceed 6 inches." Pin 18 is also listed as "Aux Ground."
2. AR850 Pin 14, "Aircraft Power," was previously connected to AT150 pin 18 "Digitizer Power." Should it now be connected to...
A. ESG pin 2/21 "Aircraft Power" via jumper/splice between those two terminals. The ESG wiring diagram shows those two terminals jumped and connected to aircraft power via a 5A breaker, with the same "6 inch max" from splice to unit caveat.
B. Aircraft Power via it's own new 2A breaker.
3. AR850 Pin 6 "Enable" was previously attached to AT150 Pin 5 "Digitizer Common." Should it now be connected to...
A. ESG pin 37 "Altitude Common."
B. Aircraft Ground.
C. External switch to ground.
I'm not really sure which box (ESG or AR850) is responsible for enabling the Mode C/altitude reporting output. The AR850 manual states..
"Activating the AR850 requires that a ground be applied to P101-6,
the ENABLE input, only when the transponder is placed in the
altitude mode. Normally the transponder would be the ground
source....
If the transponder's internal ENABLE source is a permanent ground
and not altitude mode controlled, the AR850 will be permanently
enabled. When the altitude reporter is permanently enabled, the
companion transponder must have additional internal circuitry
designed to inhibit the transmission of altitude information when
it is operating in other than the altitude mode. If the
transponder cannot meet this requirement, the AR850 ENABLE input
must be controlled by a panel mounted switch."
DOES the ESG handle the Mode A/C/S switching, and AR850 Pin 6 can just be grounded keeping the AR850 active all of the time, or does attaching it to ESG Pin 7 "Altitude Common" take care of this?
Heeellllllppppp......and thank you.