---------------------------------------------------------- Avionics-List Digest Archive --- Total Messages Posted Sat 09/10/11: 6 ---------------------------------------------------------- Today's Message Index: ---------------------- 1. 06:55 AM - Transponder troubles (Kelly McMullen) 2. 07:38 AM - Re: AeroElectric-List: Transponder troubles (Ed Gilroy) 3. 09:12 AM - Re: Transponder troubles (Francis Herr) 4. 09:19 AM - Re: Transponder troubles (George Steube) 5. 10:49 AM - Re: Transponder troubles (Charlie England) 6. 01:55 PM - Re: Transponder troubles (Pete Christensen) ________________________________ Message 1 _____________________________________ Time: 06:55:38 AM PST US Subject: Avionics-List: Transponder troubles From: Kelly McMullen Had strange occurrence with Salt Lake Approach yesterday. Initially, when they said they couldn't see my transponder, I had a reply light. Then they said they could see a 1200 code from it, not the 0363 assigned that I had dialed in. A bit later they saw the correct code, and it continued to be okay until out of their airspace. Now I departed the Phoenix area the day before, communicating with 2 radar equipped towers that had no complaints on my transponder and were giving me radar traffic callouts, so I know it was working. Not sure how a transponder could possibly put out a 1200 code when set to something else, and then revert to sending the selected code. I could see one or two digits being wrong, but the whole code? I could only think they had a weak signal, but checked after I landed and antenna was clean. I guess I can check the coax connection, and reseat the unit in its tray, but would rather not have to spend for an unnecessary bench check. It is an old model with cavity tube, but has been rock solid since it was aligned 8 yrs ago, passing every biennial check. Any other thoughts? ________________________________ Message 2 _____________________________________ Time: 07:38:24 AM PST US Subject: Avionics-List: Re: AeroElectric-List: Transponder troubles From: Ed Gilroy I had something similar happen to me only a few weeks ago arriving at Lancaster, PA. I was on a discrete code from prior flight following services and the tower said I was squawking 1200. A quick right turn followed by a look down revealed a VERY close VFR aircraft underneath me on my exact original course which was the runway heading for a straight in to the active. Was he blanketing my signal in some manner? unknown. Once I had diverged a bit the tower began seeing my signal and correct discrete code. I wonder how long we had been flying in "un-intentional formation"? On Sat, Sep 10, 2011 at 9:52 AM, Kelly McMullen wrote: > --> AeroElectric-List message posted by: Kelly McMullen < > kellym@aviating.com> > > Had strange occurrence with Salt Lake Approach yesterday. Initially, > when they said they couldn't see my transponder, I had a reply light. > Then they said they could see a 1200 code from it, not the 0363 > assigned that I had dialed in. A bit later they saw the correct code, > and it continued to be okay until out of their airspace. Now I > departed the Phoenix area the day before, communicating with 2 radar > equipped towers that had no complaints on my transponder and were > giving me radar traffic callouts, so I know it was working. Not sure > how a transponder could possibly put out a 1200 code when set to > something else, and then revert to sending the selected code. I could > see one or two digits being wrong, but the whole code? I could only > think they had a weak signal, but checked after I landed and antenna > was clean. I guess I can check the coax connection, and reseat the > unit in its tray, but would rather not have to spend for an > unnecessary bench check. It is an old model with cavity tube, but has > been rock solid since it was aligned 8 yrs ago, passing every biennial > check. Any other thoughts? > > ________________________________ Message 3 _____________________________________ Time: 09:12:27 AM PST US Subject: Re: Avionics-List: Transponder troubles From: Francis Herr Maybe there was another plane close by you (confusion by approach) or morse likely the controller simply messed up? I would wait and see or run it over a few towered airports before I would do anything drastic. My 2 cents Francis On Sep 10, 2011, at 9:52 AM, Kelly McMullen wrote: Had strange occurrence with Salt Lake Approach yesterday. Initially, when they said they couldn't see my transponder, I had a reply light. Then they said they could see a 1200 code from it, not the 0363 assigned that I had dialed in. A bit later they saw the correct code, and it continued to be okay until out of their airspace. Now I departed the Phoenix area the day before, communicating with 2 radar equipped towers that had no complaints on my transponder and were giving me radar traffic callouts, so I know it was working. Not sure how a transponder could possibly put out a 1200 code when set to something else, and then revert to sending the selected code. I could see one or two digits being wrong, but the whole code? I could only think they had a weak signal, but checked after I landed and antenna was clean. I guess I can check the coax connection, and reseat the unit in its tray, but would rather not have to spend for an unnecessary bench check. It is an old model with cavity tube, but has been rock solid since it was aligned 8 yrs ago, passing every biennial check. Any other thoughts? ________________________________ Message 4 _____________________________________ Time: 09:19:23 AM PST US From: "George Steube" Subject: RE: Avionics-List: Transponder troubles It's ATC problem. I have had the same issue with ATC on a number of occasions, if one radar site has a problem and nobody else does I wouldn't be in a hurry to get to the repair shop. George -----Original Message----- From: owner-avionics-list-server@matronics.com [mailto:owner-avionics-list-server@matronics.com]On Behalf Of Kelly McMullen Sent: Saturday, September 10, 2011 8:52 AM Subject: Avionics-List: Transponder troubles Had strange occurrence with Salt Lake Approach yesterday. Initially, when they said they couldn't see my transponder, I had a reply light. Then they said they could see a 1200 code from it, not the 0363 assigned that I had dialed in. A bit later they saw the correct code, and it continued to be okay until out of their airspace. Now I departed the Phoenix area the day before, communicating with 2 radar equipped towers that had no complaints on my transponder and were giving me radar traffic callouts, so I know it was working. Not sure how a transponder could possibly put out a 1200 code when set to something else, and then revert to sending the selected code. I could see one or two digits being wrong, but the whole code? I could only think they had a weak signal, but checked after I landed and antenna was clean. I guess I can check the coax connection, and reseat the unit in its tray, but would rather not have to spend for an unnecessary bench check. It is an old model with cavity tube, but has been rock solid since it was aligned 8 yrs ago, passing every biennial check. Any other thoughts? ________________________________ Message 5 _____________________________________ Time: 10:49:35 AM PST US From: Charlie England Subject: Re: Avionics-List: Transponder troubles On 09/10/2011 08:52 AM, Kelly McMullen wrote: > --> Avionics-List message posted by: Kelly McMullen > > Had strange occurrence with Salt Lake Approach yesterday. Initially, > when they said they couldn't see my transponder, I had a reply light. > Then they said they could see a 1200 code from it, not the 0363 > assigned that I had dialed in. A bit later they saw the correct code, > and it continued to be okay until out of their airspace. Now I > departed the Phoenix area the day before, communicating with 2 radar > equipped towers that had no complaints on my transponder and were > giving me radar traffic callouts, so I know it was working. Not sure > how a transponder could possibly put out a 1200 code when set to > something else, and then revert to sending the selected code. I could > see one or two digits being wrong, but the whole code? I could only > think they had a weak signal, but checked after I landed and antenna > was clean. I guess I can check the coax connection, and reseat the > unit in its tray, but would rather not have to spend for an > unnecessary bench check. It is an old model with cavity tube, but has > been rock solid since it was aligned 8 yrs ago, passing every biennial > check. Any other thoughts? Another + for it being an ATC problem. One of my neighbors used to fly all over the central & southeast USA, & whenever he (and others) would fly through Memphis airspace ATC would tell them that their transponder wasn't working properly (no altitude, incorrect altitude, etc etc). The various transponders seemed to work fine around other class B/C airspace, & all had problems whenever they entered Memphis airspace. Charlie ________________________________ Message 6 _____________________________________ Time: 01:55:43 PM PST US From: Pete Christensen Subject: Re: Avionics-List: Transponder troubles Not saying this happened to you but my transponder transmitted the wrong code once. A tech told me to turn the knobs once in awhile because they can develop a dirty contact since I fly around on 1200 all the time. Pete On 9/10/2011 8:52 AM, Kelly McMullen wrote: > --> Avionics-List message posted by: Kelly McMullen > > Had strange occurrence with Salt Lake Approach yesterday. Initially, > when they said they couldn't see my transponder, I had a reply light. > Then they said they could see a 1200 code from it, not the 0363 > assigned that I had dialed in. A bit later they saw the correct code, > and it continued to be okay until out of their airspace. Now I > departed the Phoenix area the day before, communicating with 2 radar > equipped towers that had no complaints on my transponder and were > giving me radar traffic callouts, so I know it was working. Not sure > how a transponder could possibly put out a 1200 code when set to > something else, and then revert to sending the selected code. I could > see one or two digits being wrong, but the whole code? I could only > think they had a weak signal, but checked after I landed and antenna > was clean. I guess I can check the coax connection, and reseat the > unit in its tray, but would rather not have to spend for an > unnecessary bench check. It is an old model with cavity tube, but has > been rock solid since it was aligned 8 yrs ago, passing every biennial > check. Any other thoughts? > > ------------------------------------------------------------------------------------- Other Matronics Email List Services ------------------------------------------------------------------------------------- Post A New Message avionics-list@matronics.com UN/SUBSCRIBE http://www.matronics.com/subscription List FAQ http://www.matronics.com/FAQ/Avionics-List.htm Web Forum Interface To Lists http://forums.matronics.com Matronics List Wiki http://wiki.matronics.com Full Archive Search Engine http://www.matronics.com/search 7-Day List Browse http://www.matronics.com/browse/avionics-list Browse Digests http://www.matronics.com/digest/avionics-list Browse Other Lists http://www.matronics.com/browse Live Online Chat! http://www.matronics.com/chat Archive Downloading http://www.matronics.com/archives Photo Share http://www.matronics.com/photoshare Other Email Lists http://www.matronics.com/emaillists Contributions http://www.matronics.com/contribution ------------------------------------------------------------------------------------- These Email List Services are sponsored solely by Matronics and through the generous Contributions of its members.