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Deems Davis

Joined: 09 Jan 2006
Posts: 925

Posted: Tue Apr 21, 2009 6:21 pm Post subject: Transponder questions

Today, I was informed by tower that they were not receiving my 

transponder, (GTX 327). Once back on the ground, I dug out the 

installation manual, and found a diagnostic 'page' on the display that 

purports to display the encoder input altitude, It displays both the 

binary, as well as the decoded altitude, In this case it was displaying 

1300 ft (baro adjust altitude at the field was 1400). To my uneducated 

mind this suggests that the encoder is providing some (perhaps 

erroneous). Alltitude info to the transponder. So. where should I look 

next?  I originally had the 'pole' antenna installed, but changed it out 

for the Commant blade style, Is the antenna/coax/ connections the next 

logical place to look.

Any suggestions gladly received?



Deems Davis

N519PJ Phase1

gengrumpy(at)aol.com
Guest

Posted: Tue Apr 21, 2009 6:36 pm Post subject: Transponder questions

Might be time to invest in the IFR cert if you have an avionics guy on  

your airport.......



grumpy



do not archive

On Apr 21, 2009, at 9:18 PM, Deems Davis wrote:



 	  Quote: 	
		   



 Today, I was informed by tower that they were not receiving my  

 transponder, (GTX 327). Once back on the ground, I dug out the  

 installation manual, and found a diagnostic 'page' on the display  

 that purports to display the encoder input altitude, It displays  

 both the binary, as well as the decoded altitude, In this case it  

 was displaying 1300 ft (baro adjust altitude at the field was 1400).  

 To my uneducated mind this suggests that the encoder is providing  

 some (perhaps erroneous). Alltitude info to the transponder. So.  

 where should I look next?  I originally had the 'pole' antenna  

 installed, but changed it out for the Commant blade style, Is the  

 antenna/coax/ connections the next logical place to look.

 Any suggestions gladly received?



 Deems Davis

 N519PJ Phase1

Kelly McMullen

Joined: 16 Apr 2008
Posts: 1188
Location: Sun Lakes AZ

Posted: Tue Apr 21, 2009 6:38 pm Post subject: Transponder questions

Were they not seeing transponder reply, or just altitude? IMHO, you

need a transponder certification anyway. Atlantic, nee Westwind used

to have that capability, and relatively cheap for VFR cert. Since you

are in Class B 30 mile arc, you need a fix pronto before the FSDO

takes an interest.



On Tue, Apr 21, 2009 at 7:18 PM, Deems Davis <deemsdavis(at)cox.net> wrote:

 	  Quote: 	
		   



 Today, I was informed by tower that they were not receiving my transponder,

 (GTX 327). Once back on the ground, I dug out the installation manual, and

 found a diagnostic 'page' on the display that purports to display the

 encoder input altitude, It displays both the binary, as well as the decoded

 altitude, In this case it was displaying 1300 ft (baro adjust altitude at

 the field was 1400). To my uneducated mind this suggests that the encoder is

 providing some (perhaps erroneous). Alltitude info to the transponder. So.

 where should I look next?  I originally had the 'pole' antenna installed,

 but changed it out for the Commant blade style, Is the antenna/coax/

 connections the next logical place to look.

 Any suggestions gladly received?



 Deems Davis

 N519PJ Phase1

_________________
Kelly McMullen
A&P/IA, EAA Tech Counselor
KCHD

Deems Davis

Joined: 09 Jan 2006
Posts: 925

Posted: Tue Apr 21, 2009 7:40 pm Post subject: Transponder questions

Kelly they aren't seeing anything, and I'm not seeing any 

'pings/replies' on the unit in the panel. I agree, this needs to get 

fixed before going aloft again, don't want to wake up the bear. I do 

need the cert, but I need to have something certifiable, which at 

present I don't. I'm going to go down the antenna route, coax, pins, 

shield, connectors, ground, etc. and see if that leads to an improvement.

Deems

Kelly McMullen wrote:

 	  Quote: 	

 Were they not seeing transponder reply, or just altitude? IMHO, you

 need a transponder certification anyway. Atlantic, nee Westwind used

 to have that capability, and relatively cheap for VFR cert. Since you

 are in Class B 30 mile arc, you need a fix pronto before the FSDO

 takes an interest.

 On Tue, Apr 21, 2009 at 7:18 PM, Deems Davis <deemsdavis(at)cox.net> wrote:

> 

>

> Today, I was informed by tower that they were not receiving my transponder,

> (GTX 327). Once back on the ground, I dug out the installation manual, and

> found a diagnostic 'page' on the display that purports to display the

> encoder input altitude, It displays both the binary, as well as the decoded

> altitude, In this case it was displaying 1300 ft (baro adjust altitude at

> the field was 1400). To my uneducated mind this suggests that the encoder is

> providing some (perhaps erroneous). Alltitude info to the transponder. So.

> where should I look next?  I originally had the 'pole' antenna installed,

> but changed it out for the Commant blade style, Is the antenna/coax/

> connections the next logical place to look.

> Any suggestions gladly received?

>

> Deems Davis

> N519PJ Phase1

>

Kelly McMullen

Joined: 16 Apr 2008
Posts: 1188
Location: Sun Lakes AZ

Posted: Tue Apr 21, 2009 8:06 pm Post subject: Transponder questions

You are fortunate in that there is at least one, probably two ATC

radars that should splash DVT if you are clear of the hangars, on the

north ramp. PHX has a new one at Union Hills and Central Ave, and of

course Luke's radar is pretty new and also close by. So if you power

up from external power, you should be able to test ping on the ground.

With the unit getting power, lighting up, either your antenna isn't

feeding a signal in, to trigger a reply, or the transponder output is

no good. Avionics shop may be willing to see if it works on the bench,

gratis. Infant mortality is not unheard of.



On Tue, Apr 21, 2009 at 8:30 PM, Deems Davis <deemsdavis(at)cox.net> wrote:

 	  Quote: 	
		   



 Kelly they aren't seeing anything, and I'm not seeing any 'pings/replies' on

 the unit in the panel. I agree, this needs to get fixed before going aloft

 again, don't want to wake up the bear. I do need the cert, but I need to

 have something certifiable, which at present I don't. I'm going to go down

 the antenna route, coax, pins, shield, connectors, ground, etc. and see if

 that leads to an improvement.



 Deems

 Kelly McMullen wrote:

>

> 

>

> Were they not seeing transponder reply, or just altitude? IMHO, you

> need a transponder certification anyway. Atlantic, nee Westwind used

> to have that capability, and relatively cheap for VFR cert. Since you

> are in Class B 30 mile arc, you need a fix pronto before the FSDO

> takes an interest.

>

> On Tue, Apr 21, 2009 at 7:18 PM, Deems Davis <deemsdavis(at)cox.net> wrote:

>

>>

>> 

>>

>> Today, I was informed by tower that they were not receiving my

>> transponder,

>> (GTX 327). Once back on the ground, I dug out the installation manual,

>> and

>> found a diagnostic 'page' on the display that purports to display the

>> encoder input altitude, It displays both the binary, as well as the

>> decoded

>> altitude, In this case it was displaying 1300 ft (baro adjust altitude at

>> the field was 1400). To my uneducated mind this suggests that the encoder

>> is

>> providing some (perhaps erroneous). Alltitude info to the transponder.

>> So.

>> where should I look next?  I originally had the 'pole' antenna installed,

>> but changed it out for the Commant blade style, Is the antenna/coax/

>> connections the next logical place to look.

>> Any suggestions gladly received?

>>

>> Deems Davis

>> N519PJ Phase1

>>

>>

>>

>>

>>

>>

>>

>>

>>

_________________
Kelly McMullen
A&P/IA, EAA Tech Counselor
KCHD

Barry Chapman

Joined: 16 Apr 2008
Posts: 11
Location: Lone Wolf, OK

Posted: Wed Apr 22, 2009 3:43 am Post subject: Transponder questions

Since the antenna was changed out, some things come to mind.  1) was the coax re-hooked back up to the new antenna?  2) A way to troubleshoot would be to put the pole antenna back on and see if they see you, if they do then it's the new antenna; if not then it's the xpdr or the wiring. 3) You could have messed up the antenna coax connector when you chnged the antenna out.  4) Anyone near by that would be willing to let you put your xpdr in their plane?  Would be a quick way to see if it is the xpdr or your wiring.

 Hope this helps

 Barry Chapman

 RV9A

   From: Kelly McMullen <apilot2(at)gmail.com>

To: rv10-list(at)matronics.com

Sent: Tuesday, April 21, 2009 11:03:35 PM

Subject: Re: Transponder questions

--> RV10-List message posted by: Kelly McMullen <apilot2(at)gmail.com (apilot2(at)gmail.com)>

You are fortunate in that there is at least one, probably two ATC

radars that should splash DVT if you are clear of the hangars, on the

north ramp. PHX has a new one at Union Hills and Central Ave, and of

course Luke's radar is pretty new and also close by. So if you power

up from external power, you should be able to test ping on the ground.

With the unit getting power, lighting up, either your antenna isn't

feeding a  signal in, to trigger a reply, or the transponder output is

no good. Avionics shop may be willing to see if it works on the bench,

gratis. Infant mortality is not unheard of.

On Tue, Apr 21, 2009 at 8:30 PM, Deems Davis <deemsdavis(at)cox.net (deemsdavis(at)cox.net)> wrote:

 	  Quote: 	
		   --> RV10-List message posted by: Deems Davis <deemsdavis(at)cox.net (deemsdavis(at)cox.net)>

 Kelly they aren't seeing anything, and I'm not seeing any 'pings/replies' on

 the unit in the panel. I agree, this needs to get fixed before going aloft

 again, don't want to wake up the bear. I do need the cert, but I need to

 have something certifiable, which at present I don't. I'm going to go down

 the antenna route, coax, pins, shield, connectors, ground, etc. and see if

 that leads to an  improvement.

 Deems

 Kelly McMullen wrote:

>

> --> RV10-List message posted by: Kelly McMullen <apilot2(at)gmail.com (apilot2(at)gmail.com)>

>

> Were they not seeing transponder reply, or just altitude? IMHO, you

> need a transponder certification anyway. Atlantic, nee Westwind used

> to have that capability, and relatively cheap for VFR cert. Since you

> are in Class B 30 mile arc, you need a fix pronto before the FSDO

> takes an interest.

>

> On Tue, Apr 21, 2009 at 7:18 PM, Deems Davis <deemsdavis(at)cox.net (deemsdavis(at)cox.net)> wrote:

>

>>

>> --> RV10-List message posted by: Deems Davis <deemsdavis(at)cox.net (deemsdavis(at)cox.net)>

>>

>> Today, I was informed by tower that they were not receiving my

>> transponder,

>> (GTX 327). Once back on the ground, I dug out the installation manual,

>> and

>> found a diagnostic 'page' on the display that purports to display the

>> encoder input altitude, It displays both the binary, as well as the

>> decoded

>> altitude, In this case it was displaying 1300 ft (baro adjust altitude at

>> the field was 1400). To my uneducated mind this suggests that the encoder

>> is

>> providing some (perhaps erroneous). Alltitude info to the transponder.

>> So.

>> where should I look next?  I originally had the 'pole' antenna installed,

>> but changed it out for the Commant blade style, Is the  antenna/coax/

>> connections the next logical place to look.

>> Any suggestions gladly received?

>>

>> Deems Davis

>> N519PJ Phase1

>>

>>

>>

>>

>>

>>

>>

>>

>>

&bsp;                 -Matt Dralle, ===========

 [quote][b]

_________________
Barry Chapman
RV-9A in progress
Tail complete, Wings here, Engine needs rebuilt

msausen

Joined: 25 Oct 2007
Posts: 559
Location: Appleton, WI USA

Posted: Wed Apr 22, 2009 4:34 am Post subject: Transponder questions

That was kinda my thought too.  If the coax is quick and easy to get to check that first otherwise I would see if someone can bench test it just you you can eliminate that as a possibility.  If you suspect the unit, let me know and I can send you my 327 to give a try.



Michael



--

Tim Olson

Joined: 25 Jan 2007
Posts: 2872

Posted: Wed Apr 22, 2009 4:34 am Post subject: Transponder questions

Forgive me for asking the obvious, but, you did select

ALT mode on the transponder, correct?  I've seen some

people go flying without doing that (if you don't provide

some way for the transponder to auto-sense you're flying)

and then not get any altitude readout to ATC.



Tim Olson - RV-10 N104CD - Flying

do not archive

Deems Davis wrote:

 	  Quote: 	
		   

 

 Kelly they aren't seeing anything, and I'm not seeing any 

 'pings/replies' on the unit in the panel. I agree, this needs to get 

 fixed before going aloft again, don't want to wake up the bear. I do 

 need the cert, but I need to have something certifiable, which at 

 present I don't. I'm going to go down the antenna route, coax, pins, 

 shield, connectors, ground, etc. and see if that leads to an improvement.

 

 Deems

 

 

 Kelly McMullen wrote:

> 

>

> Were they not seeing transponder reply, or just altitude? IMHO, you

> need a transponder certification anyway. Atlantic, nee Westwind used

> to have that capability, and relatively cheap for VFR cert. Since you

> are in Class B 30 mile arc, you need a fix pronto before the FSDO

> takes an interest.

>

> On Tue, Apr 21, 2009 at 7:18 PM, Deems Davis <deemsdavis(at)cox.net> wrote:

>  

>> 

>>

>> Today, I was informed by tower that they were not receiving my 

>> transponder,

>> (GTX 327). Once back on the ground, I dug out the installation 

>> manual, and

>> found a diagnostic 'page' on the display that purports to display the

>> encoder input altitude, It displays both the binary, as well as the 

>> decoded

>> altitude, In this case it was displaying 1300 ft (baro adjust 

>> altitude at

>> the field was 1400). To my uneducated mind this suggests that the 

>> encoder is

>> providing some (perhaps erroneous). Alltitude info to the 

>> transponder. So.

>> where should I look next?  I originally had the 'pole' antenna 

>> installed,

>> but changed it out for the Commant blade style, Is the antenna/coax/

>> connections the next logical place to look.

>> Any suggestions gladly received?

>>

>> Deems Davis

>> N519PJ Phase1

>>

>>

>>

>>

>>

>>

>>

>>

>>     

>

>

jim(at)CombsFive.Com
Guest

Posted: Wed Apr 22, 2009 4:43 am Post subject: Transponder questions

(1) Check to see if the transponder is showing the reply indicator on the display.  That is an indication that it is attempting to transmit.  (I had a bad cable and even though the unit was doing the reply, it was not going out).  The cable connector was faulty (My fault!)(2) Check the setup in the transponder as to what it is expecting from the EFIS.  You may need to check the EFIS manual for the proper setup. Jim C40192 - Flying - 58 hours!--------------------------------------------------------------------------------------------------------------------------> RV10-List message posted by: Deems Davis <deemsdavis(at)cox.net>Today, I was informed by tower that they were not receiving mytransponder, (GTX 327). Once back on the ground, I dug out theinstallation manual, and found a diagnostic 'page' on the display thatpurports to display the encoder input altitude, It displays both thebinary, as well as the decoded altitude, In this case it was displaying1300 ft (baro adjust altitude at the field was 1400). To my uneducatedmind this suggests that the encoder is providing some (perhapserroneous). Alltitude info to the transponder. So. where should I looknext?  I originally had the 'pole' antenna installed, but changed it outfor the Commant blade style, Is the antenna/coax/ connections the nextlogical place to look.Any suggestions gladly received?Deems DavisN519PJ Phase1   [quote][b]

jesse(at)saintaviation.co
Guest

Posted: Wed Apr 22, 2009 4:57 am Post subject: Transponder questions

It might be a good idea to pull out your unit & slide it in another  

plane to verify the unit is good.  Then I'd check for continuity & no  

short in the antenna cable.  If that checks good, then maybe the  

antenna, but it probably is something simple & obvious once you get to  

checking.



Do not archive



Jesse Saint

Saint Aviation

jesse(at)saintaviation.com

352-427-0285



Sent from my iPhone



On Apr 21, 2009, at 11:30 PM, Deems Davis <deemsdavis(at)cox.net> wrote:



 	  Quote: 	
		   



 Kelly they aren't seeing anything, and I'm not seeing any 'pings/ 

 replies' on the unit in the panel. I agree, this needs to get fixed  

 before going aloft again, don't want to wake up the bear. I do need  

 the cert, but I need to have something certifiable, which at present  

 I don't. I'm going to go down the antenna route, coax, pins, shield,  

 connectors, ground, etc. and see if that leads to an improvement.



 Deems

 Kelly McMullen wrote:

> 

>

> Were they not seeing transponder reply, or just altitude? IMHO, you

> need a transponder certification anyway. Atlantic, nee Westwind used

> to have that capability, and relatively cheap for VFR cert. Since you

> are in Class B 30 mile arc, you need a fix pronto before the FSDO

> takes an interest.

>

> On Tue, Apr 21, 2009 at 7:18 PM, Deems Davis <deemsdavis(at)cox.net>  

> wrote:

>

>> 

>>

>> Today, I was informed by tower that they were not receiving my  

>> transponder,

>> (GTX 327). Once back on the ground, I dug out the installation  

>> manual, and

>> found a diagnostic 'page' on the display that purports to display  

>> the

>> encoder input altitude, It displays both the binary, as well as  

>> the decoded

>> altitude, In this case it was displaying 1300 ft (baro adjust  

>> altitude at

>> the field was 1400). To my uneducated mind this suggests that the  

>> encoder is

>> providing some (perhaps erroneous). Alltitude info to the  

>> transponder. So.

>> where should I look next?  I originally had the 'pole' antenna  

>> installed,

>> but changed it out for the Commant blade style, Is the antenna/coax/

>> connections the next logical place to look.

>> Any suggestions gladly received?

>>

>> Deems Davis

>> N519PJ Phase1

>>

>>

>>

>>

>>

>>

>>

>>

>>

Deems Davis

Joined: 09 Jan 2006
Posts: 925

Posted: Wed Apr 22, 2009 6:14 am Post subject: Transponder questions

Thanks to all who responded with information & suggestions. I did verify 

in the air that the ALT func was selected, but no replies were being 

seen in the panel. I hadn't thought of swapping, but that's a great 

idea, shouldn''t be too hard to find someone to help out on that end.  

Short of that, I'll have to tear out the center console and it's gadgets 

in order to get into the tunnel where the antenna and cable are 

mounted/routed.



URGH!!!



Deems

 	  Quote:

rv6(at)att.net
Guest

Posted: Wed Apr 22, 2009 8:06 am Post subject: Transponder questions

Make sure antenna is grounded to mounting area.  Might need to rough up the

aluminum on inside of cockpit if it is painted or primed, use an aluminum

plate with nut plates to accept antenna screws.  The plate should ground to

the skin.



Jerry



--

n223rv(at)wolflakeairport
Guest

Posted: Wed Apr 22, 2009 8:21 am Post subject: Transponder questions

Before you do all that, make sure you pull out and re-seat the radio  

in the tray real well.  Many times it is just a bad connection between  

the radio and the tray itself...



Sent from my iPhone



On Apr 22, 2009, at 10:11 AM, Deems Davis <deemsdavis(at)cox.net> wrote:

Bob Turner

Joined: 03 Jan 2009
Posts: 885
Location: Castro Valley, CA

Posted: Wed Apr 22, 2009 9:21 am Post subject: Re: Transponder questions

BTW, the altitude readout on the transponder is pressure altitude. To check its accuracy, set the aircraft altimeter to 29.92".

_________________
Bob Turner
RV-10 QB

robin1(at)mrmoisture.com
Guest

Posted: Wed Apr 22, 2009 9:30 am Post subject: Transponder questions

Is that the pain of which you were speaking?



Robin

Do Not Archive



--

Deems Davis

Joined: 09 Jan 2006
Posts: 925

Posted: Wed Apr 22, 2009 2:12 pm Post subject: Transponder questions

Yeah, and I was kinda hoping that I had made my last trip upside down 

underneath the panel until annual time!!!



Deems



Robin Marks wrote:

[quote] 



 Is that the pain of which you were speaking?



 Robin

 Do Not Archive



 --

Deems Davis

Joined: 09 Jan 2006
Posts: 925

Posted: Wed Apr 22, 2009 7:19 pm Post subject: Transponder questions

Jerry, after noodling on this, I actually think this might be the 

culpret. And will be the 1st place I look. I changed out the original 

'pole' antenna for a 'blade' type during the build process, and in doing 

so I also installed a doubler, in looking back at the photo log it 

appears that I primed the double before attaching it !?!? . I pulled the 

unit and took it to an avionics shop on field today and they put it on 

their tester and said it was clean, so either the encoder & connections 

or antenna & connections.



Thanks to all for the help so far.



Deems



I also tried the unseat and reseat step.



Jerry Calvert wrote:

 	  Quote: 	
		   



 Make sure antenna is grounded to mounting area.  Might need to rough up the

 aluminum on inside of cockpit if it is painted or primed, use an aluminum

 plate with nut plates to accept antenna screws.  The plate should ground to

 the skin.



 Jerry

Kelly McMullen

Joined: 16 Apr 2008
Posts: 1188
Location: Sun Lakes AZ

Posted: Wed Apr 22, 2009 8:01 pm Post subject: Transponder questions

You also could disconnect the encoder, after verifying the antenna

grounding and see if it works in Mode A only. KISS. One step at a

time, get the basic unit working, then the encoder.

On Wed, Apr 22, 2009 at 8:16 PM, Deems Davis <deemsdavis(at)cox.net> wrote:

 	  Quote: 	

 Jerry, after noodling on this, I actually think this might be the culpret.

 And will be the 1st place I look. I changed out the original 'pole' antenna

 for a 'blade' type during the build process, and in doing so I also

 installed a doubler, in looking back at the photo log it appears that I

 primed the double before attaching it !?!? . I pulled the unit and took it

 to an avionics shop on field today and they put it on their tester and said

 it was clean, so either the encoder & connections or antenna & connections.

 Thanks to all for the help so far.

 Deems

 I also tried the unseat and reseat step.

 Jerry Calvert wrote:

>

> 

>

> Make sure antenna is grounded to mounting area.  Might need to rough up

> the

> aluminum on inside of cockpit if it is painted or primed, use an aluminum

> plate with nut plates to accept antenna screws.  The plate should ground

> to

> the skin.

>

> Jerry

>

_________________
Kelly McMullen
A&P/IA, EAA Tech Counselor
KCHD

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