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ASW27 Trasponder Antenna Installation Inside Fuselage.



 
 
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  #31  
Old December 31st 17, 09:08 PM posted to rec.aviation.soaring
Darryl Ramm
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Posts: 2,403
Default ASW27 Trasponder Antenna Installation Inside Fuselage.

On Sunday, December 31, 2017 at 11:25:42 AM UTC-8, Scott Williams wrote:
On Sunday, December 31, 2017 at 12:58:25 PM UTC-6, Darryl Ramm wrote:
On Sunday, December 31, 2017 at 10:03:37 AM UTC-8, Scott Williams wrote:
On Sunday, December 31, 2017 at 7:33:39 AM UTC-6, wrote:
AC 43.13B 308d says you need a backing ground plane.
But I didn't see any special details for CF versus other composites?

Following the instructions from the glider manufacturer seems smart..

My std Cirrus has a schempp-Hirth TN that clearly spells out the installation
of the blade antenna. but it allows either aluminum or copper for a ground plane.
I chose a copper plate 0f .043 thick.
Trigg 22 has good output, but the 'sensitivity' was right on the low tolerance.
Any thoughts or insights?
thanks,
Scott


What did the technician doing the test recommend? If there was a doubt why did they not direct connect test the transponder?

These measurements are not highly precise. If its within tolerance then go fly. If not then get a different avionics technician to repeat the test if possible and if its bad then direct connect test the transponder to see it is likely the transponder or cable/antenna..


in short,
New trig tt22, new only 14 inch antenna coax, new antenna, copper ground plane, trig authorized shop doing test, fresh battery with good voltage.
Tech reports using two different 'test rigs' , also report "sensitivity is on the low tolerance, but I'll pass it" with no other suggestions.
I followed up with Trig factory tech line, maybe have to send it in for a factory check. Factory rep had on suggestions.
I have no idea just what 'sensitivity is. factory was helpful, but I think maybe "sensitivity" may be outside of the influence of installation variables.
I was hoping for someone to have an insight.

Thanks,
Scott


Did they direct connect test the transponder?

Sensitivity is the transponder sensitivity to interrogation. A poor antenna or coax install will affect that the same as it will affect the transmitted power. You can compare the radiated power measurements and guess the loss, but you don't know with much precision what that is if measured by a radiated test. The radiated tests are pretty imprecise, they are not done in free space, they have reflections and lots of stuff going on. If a direct connect test to the transponder with a different coax shows a marginal result then the Trig agent/test shop would hopefully be discussing that for you with mid-century.

The proper thing to do here if in doubt was just direct connect the transponder to a test kit. Did the technician do that? If not was the test kit not capable?? (I can't recall one that isn't but could be wrong)? He didn't have a coax or adapters with him? He really though it was just not an issue to waste time on? The shop/technician should have been able to answer all the questions you seem to have here questions and do more troubleshooting (maybe for a fee) especially after discussion if you still had concern.

  #32  
Old December 31st 17, 10:22 PM posted to rec.aviation.soaring
Scott Williams
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Posts: 198
Default ASW27 Trasponder Antenna Installation Inside Fuselage.

On Sunday, December 31, 2017 at 2:08:17 PM UTC-6, Darryl Ramm wrote:
On Sunday, December 31, 2017 at 11:25:42 AM UTC-8, Scott Williams wrote:
On Sunday, December 31, 2017 at 12:58:25 PM UTC-6, Darryl Ramm wrote:
On Sunday, December 31, 2017 at 10:03:37 AM UTC-8, Scott Williams wrote:
On Sunday, December 31, 2017 at 7:33:39 AM UTC-6, wrote:
AC 43.13B 308d says you need a backing ground plane.
But I didn't see any special details for CF versus other composites?

Following the instructions from the glider manufacturer seems smart.

  #33  
Old December 31st 17, 11:13 PM posted to rec.aviation.soaring
Dan Marotta
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Posts: 4,601
Default ASW27 Trasponder Antenna Installation Inside Fuselage.

If it's not too much trouble, try a coax cable length of 21 11/16 inches
which would be 2 wavelengths at 1090 MHz (assuming my arithmetic is
correct).Â* You may have reflected power in your coax which will reduce
performance.

On 12/31/2017 2:22 PM, Scott Williams wrote:
On Sunday, December 31, 2017 at 2:08:17 PM UTC-6, Darryl Ramm wrote:
On Sunday, December 31, 2017 at 11:25:42 AM UTC-8, Scott Williams wrote:
On Sunday, December 31, 2017 at 12:58:25 PM UTC-6, Darryl Ramm wrote:
On Sunday, December 31, 2017 at 10:03:37 AM UTC-8, Scott Williams wrote:
On Sunday, December 31, 2017 at 7:33:39 AM UTC-6, wrote:
AC 43.13B 308d says you need a backing ground plane.
But I didn't see any special details for CF versus other composites?

Following the instructions from the glider manufacturer seems smart.
My std Cirrus has a schempp-Hirth TN that clearly spells out the installation
of the blade antenna. but it allows either aluminum or copper for a ground plane.
I chose a copper plate 0f .043 thick.
Trigg 22 has good output, but the 'sensitivity' was right on the low tolerance.
Any thoughts or insights?
thanks,
Scott
What did the technician doing the test recommend? If there was a doubt why did they not direct connect test the transponder?

These measurements are not highly precise. If its within tolerance then go fly. If not then get a different avionics technician to repeat the test if possible and if its bad then direct connect test the transponder to see it is likely the transponder or cable/antenna..
in short,
New trig tt22, new only 14 inch antenna coax, new antenna, copper ground plane, trig authorized shop doing test, fresh battery with good voltage.
Tech reports using two different 'test rigs' , also report "sensitivity is on the low tolerance, but I'll pass it" with no other suggestions.
I followed up with Trig factory tech line, maybe have to send it in for a factory check. Factory rep had on suggestions.
I have no idea just what 'sensitivity is. factory was helpful, but I think maybe "sensitivity" may be outside of the influence of installation variables.
I was hoping for someone to have an insight.

Thanks,
Scott

Did they direct connect test the transponder?

Sensitivity is the transponder sensitivity to interrogation. A poor antenna or coax install will affect that the same as it will affect the transmitted power. You can compare the radiated power measurements and guess the loss, but you don't know with much precision what that is if measured by a radiated test. The radiated tests are pretty imprecise, they are not done in free space, they have reflections and lots of stuff going on. If a direct connect test to the transponder with a different coax shows a marginal result then the Trig agent/test shop would hopefully be discussing that for you with mid-century.

The proper thing to do here if in doubt was just direct connect the transponder to a test kit. Did the technician do that? If not was the test kit not capable?? (I can't recall one that isn't but could be wrong)? He didn't have a coax or adapters with him? He really though it was just not an issue to waste time on? The shop/technician should have been able to answer all the questions you seem to have here questions and do more troubleshooting (maybe for a fee) especially after discussion if you still had concern.

the tech did not directly connect, he also admitted that the steel hangar door and wall 18 feet away "could influence" the tests, he had never done a glider and was really friendly, but only did tests with a tripod mounted radiated device. The first device only reported "failed" the second device reported the Sensitivity as a number, 68 or 69 I believe. all other aspects passed.
Initially he was willing to do a "benchtop"? but said he did not have the correct harness.

This is my first experience with transponders and I am just learning.
Scott


--
Dan, 5J
  #34  
Old January 1st 18, 01:13 AM posted to rec.aviation.soaring
Steve Koerner
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Posts: 430
Default ASW27 Trasponder Antenna Installation Inside Fuselage.

On Sunday, December 31, 2017 at 3:13:42 PM UTC-7, Dan Marotta wrote:
If it's not too much trouble, try a coax cable length of 21 11/16 inches
which would be 2 wavelengths at 1090 MHz (assuming my arithmetic is
correct).Â* You may have reflected power in your coax which will reduce
performance.


Dan: I'm not jumping into the real technical matters here but its pretty obvious that you're neglecting the fact that waves travel slower in coax.
  #35  
Old January 1st 18, 02:12 AM posted to rec.aviation.soaring
Scott Williams
external usenet poster
 
Posts: 198
Default ASW27 Trasponder Antenna Installation Inside Fuselage.

On Sunday, December 31, 2017 at 6:13:39 PM UTC-6, Steve Koerner wrote:
On Sunday, December 31, 2017 at 3:13:42 PM UTC-7, Dan Marotta wrote:
If it's not too much trouble, try a coax cable length of 21 11/16 inches
which would be 2 wavelengths at 1090 MHz (assuming my arithmetic is
correct).Â* You may have reflected power in your coax which will reduce
performance.


Dan: I'm not jumping into the real technical matters here but its pretty obvious that you're neglecting the fact that waves travel slower in coax.


Hey Dan,
I think you may be correct about Too short,
I googled this and there is a couple of opinions that seem to originate
with Garmin, I doubt very many transponders are installed with coax runs
less than 15 inches, maybe this particular problem is rare?
I'm using rg400, and may try a longer coax run.
Thanks,
Scott.
  #36  
Old January 1st 18, 02:22 AM posted to rec.aviation.soaring
Scott Williams
external usenet poster
 
Posts: 198
Default ASW27 Trasponder Antenna Installation Inside Fuselage.

On Sunday, December 31, 2017 at 7:12:51 PM UTC-6, Scott Williams wrote:
On Sunday, December 31, 2017 at 6:13:39 PM UTC-6, Steve Koerner wrote:
On Sunday, December 31, 2017 at 3:13:42 PM UTC-7, Dan Marotta wrote:
If it's not too much trouble, try a coax cable length of 21 11/16 inches
which would be 2 wavelengths at 1090 MHz (assuming my arithmetic is
correct).Â* You may have reflected power in your coax which will reduce
performance.


Dan: I'm not jumping into the real technical matters here but its pretty obvious that you're neglecting the fact that waves travel slower in coax.


Hey Dan,
I think you may be correct about Too short,
I googled this and there is a couple of opinions that seem to originate
with Garmin, I doubt very many transponders are installed with coax runs
less than 15 inches, maybe this particular problem is rare?
I'm using rg400, and may try a longer coax run.
Thanks,
Scott.


In addition,
So does anyone willing to suggest a coax length if not 21 11/16 inches?
maybe tree foot? is there a non critical length range?
Scott.
  #37  
Old January 1st 18, 02:57 AM posted to rec.aviation.soaring
Dan Marotta
external usenet poster
 
Posts: 4,601
Default ASW27 Trasponder Antenna Installation Inside Fuselage.

You're correct, Steve.Â* Better knock off a millimeter or two from the
length although the length I quoted was not precise.Â* Maybe 3 mm... :-D

Happy New Year!

On 12/31/2017 5:13 PM, Steve Koerner wrote:
On Sunday, December 31, 2017 at 3:13:42 PM UTC-7, Dan Marotta wrote:
If it's not too much trouble, try a coax cable length of 21 11/16 inches
which would be 2 wavelengths at 1090 MHz (assuming my arithmetic is
correct).Â* You may have reflected power in your coax which will reduce
performance.

Dan: I'm not jumping into the real technical matters here but its pretty obvious that you're neglecting the fact that waves travel slower in coax.


--
Dan, 5J
  #38  
Old January 1st 18, 03:02 AM posted to rec.aviation.soaring
Darryl Ramm
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Posts: 2,403
Default ASW27 Trasponder Antenna Installation Inside Fuselage.

Just leave it alone and go fly.

  #39  
Old January 1st 18, 03:25 AM posted to rec.aviation.soaring
Scott Williams
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Posts: 198
Default ASW27 Trasponder Antenna Installation Inside Fuselage.

On Sunday, December 31, 2017 at 8:02:08 PM UTC-6, Darryl Ramm wrote:
Just leave it alone and go fly.


Fundamentally I agree with you, but if my new expensive transponder installation fails recert in the future, I would have wished to correct it being only a couple of months old. rather than close to the end of the warrantee period. And I must admit to being pretty obsessive compulsive on subjects like this.
thanks,
Scott
  #40  
Old January 1st 18, 05:45 AM posted to rec.aviation.soaring
Darryl Ramm
external usenet poster
 
Posts: 2,403
Default ASW27 Trasponder Antenna Installation Inside Fuselage.

On Sunday, December 31, 2017 at 6:25:04 PM UTC-8, Scott Williams wrote:
On Sunday, December 31, 2017 at 8:02:08 PM UTC-6, Darryl Ramm wrote:
Just leave it alone and go fly.


Fundamentally I agree with you, but if my new expensive transponder installation fails recert in the future, I would have wished to correct it being only a couple of months old. rather than close to the end of the warrantee period. And I must admit to being pretty obsessive compulsive on subjects like this.
thanks,
Scott


C'mon you are wasting time, you didn't even know what the guy was talking about but that did not stop you trying to talk to the manufacturer... . He's signed off on the install. These tests are very imprecise (third time I've said that), as you should have taken away from the technician's comments and very likely don't show anything worth worrying about. If you don't trust the avionics tech who signed off on it then go elsewhere. I've already told you what the test to ask for... but given how busy shops are with ADS-B installs I expect many of them would have low tolerance for things that look like they might be wasting time, or maybe they'll be willing to charge you well for farting around with somebody else's transponder install. You are wasting time...

 




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