Avionics-List Digest Archive

Fri 09/30/11


Total Messages Posted: 5



Today's Message Index:
----------------------
 
     1. 09:33 AM - Re: Re:Transponder troubles (Doug McNutt)
     2. 12:51 PM - Re: Re:Transponder troubles (Kelly McMullen)
     3. 01:06 PM - Transponder Whip Antenna in a Composite A/C (dwwilt)
     4. 03:11 PM - Removal of Garmin GNS-430 from Instrument Panel (George Nielsen)
     5. 05:35 PM - Re: Removal of Garmin GNS-430 from Instrument Panel (Dave)
 
 
 


Message 1


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    Time: 09:33:55 AM PST US
    From: Doug McNutt <douglist@macnauchtan.com>
    Subject: Re: re:Transponder troubles
    At 18:50 -0600 9/11/11, Kelly McMullen wrote: > >A Narco AT-50. Mode A and mode C are distinguished by a time spacing between pulses received in the interrogation from the ground. Mode A inserts twelve bits as entered into you code selector. Mode C sends twelve bits of altitude information. There is also a mode B for which the details are "protected" by the US military. Those settings, in an AT50 are set with analog adjustments inside your transponder and might well have drifted out of spec. If you're sending mode C information in response to a mode A request the ground will get a code they don't expect. It might also look intermittent because it could depend on the received signal amplitude of the interrogation pulses. (How far away is the transmitter?) Ant at one time there was an AD that required transponders to reply to mode C requests even if they had altitude responding turned off. Reason: collision warning detectors is other aircraft. I believe the AT50 was one of those that was considered not worth making the modification to. That is from long term memory though and may not be quite right. Watch out, though, if you ask for a bench test. You might discover you have an illegal transponder. I'm pretty sure there was an AT-50A that came out. -- --> From the U S of A, the only socialist country that refuses to admit it. <--


    Message 2


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    Time: 12:51:56 PM PST US
    From: Kelly McMullen <kellym@aviating.com>
    Subject: Re: re:Transponder troubles
    Yes, your suspicion was correct, re the alignment. It was a bit out of spec. Once adjusted back in spec, it tested perfectly both on the bench and in the aircraft. Yes, there is an AT50A, which I think has more output power, but otherwise is pretty much the same box, and they are interchangeable, like all Narco units...same tray, same pins, etc. On 9/30/2011 9:28 AM, Doug McNutt wrote: > --> Avionics-List message posted by: Doug McNutt<douglist@macnauchtan.com> > > At 18:50 -0600 9/11/11, Kelly McMullen wrote: >> --> Avionics-List message posted by: Kelly McMullen<kellym@aviating.com> >> >> A Narco AT-50. > Mode A and mode C are distinguished by a time spacing between pulses received in the interrogation from the ground. Mode A inserts twelve bits as entered into you code selector. Mode C sends twelve bits of altitude information. There is also a mode B for which the details are "protected" by the US military. > > Those settings, in an AT50 are set with analog adjustments inside your transponder and might well have drifted out of spec. If you're sending mode C information in response to a mode A request the ground will get a code they don't expect. It might also look intermittent because it could depend on the received signal amplitude of the interrogation pulses. (How far away is the transmitter?) > > Ant at one time there was an AD that required transponders to reply to mode C requests even if they had altitude responding turned off. Reason: collision warning detectors is other aircraft. I believe the AT50 was one of those that was considered not worth making the modification to. That is from long term memory though and may not be quite right. Watch out, though, if you ask for a bench test. You might discover you have an illegal transponder. I'm pretty sure there was an AT-50A that came out. > >


    Message 3


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    Time: 01:06:55 PM PST US
    Subject: Transponder Whip Antenna in a Composite A/C
    From: "dwwilt" <dwwilt@aol.com>
    I am going to be installing a ACK Technologies ELT into my Lightning. The install manual explains that for a composite aircraft you should install a ground plane for the antenna. I want to install the antenna inside the fuselage and I am wondering if anyone has done this with an ELT. The antenna is a whip antenna and I have some ideas, that I think would work, but thought I would ask the community first. Thanks, Dennis Read this topic online here: http://forums.matronics.com/viewtopic.php?p=353656#353656


    Message 4


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    Time: 03:11:55 PM PST US
    From: George Nielsen <genie@swissmail.org>
    Subject: Removal of Garmin GNS-430 from Instrument Panel
    Could someone please tell me the step-by-step procedure on how to remove a Garmin GNS-430 from an instrument panel. Does one need any special tools? Thanks. George Nielsen RV-6 PH-XGN


    Message 5


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    Time: 05:35:07 PM PST US
    From: "Dave" <daberti@sbcglobal.net>
    Subject: Removal of Garmin GNS-430 from Instrument Panel
    Only an allen wrench to crank the unit out of the tray. A 430 has a locking leg on the bottom of the unit that pulls it in and pushes it out of the tray. Depending on the clearance in your stack you can see it just left of center on the bottom and there is a small diameter hole in the unit where the allen fits. It's about 3" below the face to the release mechanism. -----Original Message----- From: owner-avionics-list-server@matronics.com [mailto:owner-avionics-list-server@matronics.com] On Behalf Of George Nielsen Sent: Friday, September 30, 2011 5:06 PM Subject: Avionics-List: Removal of Garmin GNS-430 from Instrument Panel --> <genie@swissmail.org> Could someone please tell me the step-by-step procedure on how to remove a Garmin GNS-430 from an instrument panel. Does one need any special tools? Thanks. George Nielsen RV-6 PH-XGN




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