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billhuntersemail(at)gmail
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 Posted: Thu May 02, 2019 4:08 pm Post subject: GRT EIS Issues When Transmitting |
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Greeting,
I am posting for a friend who fly a Velocity…and I will get him to sign up for the Aeroelectric.
His Question:
I need help with further troubleshooting an anomaly. When I key the radio, all EGT & CHT temps drop about 25 degrees and stay there until the transmission is released at which time they return to normal. This is repeatable with the engine running or not. The EIS has been replaced with a brand new one. I have swapped radios on the antenna. Whichever radio is using the stbd antenna causes the anomaly. I inspected the antenna wire (RG-400) as much as possible without removing it. No wear or nicks. System, both EIS and radios have been flawless since installation in 2016. Have even installed a ferrite sleeve on the cht/egt wire bundle. No change. Transmission and reception on the radio is loud and clear.
I have a GRT EIS mounted [at the back of the copilot side of the airplane] on the floor. The wires run through the [fiberglass conduit] to the engine.
The closest the antenna gets to the EIS is about 18 inches.
…
Thanks,
Bill Hunter
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jjshultz
Joined: 19 Apr 2009
Posts: 3
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| Posted: Fri May 03, 2019 6:51 am Post subject: Re: GRT EIS Issues When Transmitting |
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I had an identical issue with my GRT EIS and an older NARCO comm radio. I surmised that the radio antenna cable was affecting the EIS EGT/CHT probe thermocouple wires leading into the EIS. I installed about 8-10 ferrite beads over the antenna cable and the EIS data wire bundle, and it helped reduce the effect. However, the ultimate solution was to reroute the radio antenna wire completely away from the EIS wires. This solved the problem completely.
Although it may not be convenient to separate the antenna cable and EIS wires, I suggest that is the best approach here.
Jeff
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nuckolls.bob(at)aeroelect
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| Posted: Sat May 04, 2019 7:32 am Post subject: GRT EIS Issues When Transmitting |
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Greeting,
I am posting for a friend who fly a Velocity?and I will get him to sign up for the Aeroelectric.
His Question:
I need help with further troubleshooting an anomaly.
When I key the radio, all EGT & CHT temps drop about
25 degrees and stay there until the transmission is
released at which time they return to normal. This is
repeatable with the engine running or not. The EIS
has been replaced with a brand new one. I have swapped
radios on the antenna. Whichever radio is using
the stbd antenna causes the anomaly. I inspected
the antenna wire (RG-400) as much as possible without
removing it. No wear or nicks. System, both EIS and
radios have been flawless since installation in 2016.
ALL instrumentation-grade electro-whizzies
have SOME vulnerability to strong local
radio energy. When design goals target
installation in aircraft, the prudent
designer will consider building
a certain level of tolerance to radio
energy. If the device is destined to
fly in TC aircraft, then legacy qualification
testing will have been conducted to verify
the designer's successful achievement of
design goals.
I was unable to quickly locate any info
on GRT claims for environmental robustness
but they've been in the game for a long
time. It seems likely that their products
demonstrate adequate robustness to EM
radiation.
Further, the difficulty you're citing
is a new condition which suggests a
profound CHANGE in conditions between
the antagonist/propagation-path/victim
triad.
As a general rule, electro-whizzies once
demonstrated to meet design goals do
not suddenly go "weak" with respect
to electro-magnetic compatibility.
This is why the FIRST line of investigation
involves researching the propagation-path
which generally consists of things 'hung
out in the breeze' with respect to
potential for damage or failure. The
fact that one of two antennas is unique
to the symptoms strongly suggests some
CHANGE in the pathway between connector
at the radio and the antenna itself.
The first thing I do in these cases is
check antenna SWR (and compare with
other antenna). I think it likely that
you'll find the 'bad' antenna has a
much higher SWR. Damaged coax is the
LEAST likely cause. Disconnection of
either the center conductor or shield
at the connectors is most likely.
A very reasonable test tool for pursuing
this investigation is seen here:
https://tinyurl.com/y64t9nse
[img]cid:.0[/img]
(caution, there are both VHF/UHF and
HF versions . . . get the VHF/UHF
device)
You'll probably also need a two-pak
of these adapters:
https://tinyurl.com/y66wn6ua
and a short BncM to BncM jumper cable
https://tinyurl.com/y3b7lvfp
Have even installed a ferrite sleeve on the cht/egt
wire bundle. No change. Transmission and reception
on the radio is loud and clear.
Ferrite sleeves are marginally effective
in meeting original design goals for
EMC . . . we used to see these included in
computer interconnect cables . . .
[img]cid:.0[/img]
. . . but in the aviation world, they're
considered an un-acceptable 'band-aid'
to a problem that should be taken care
of INSIDE the electro-whizzies. I don't
even have such things in my inventory.
I have a GRT EIS mounted [at the back of the copilot
side of the airplane] on the floor. The wires run through the
[fiberglass conduit] to the engine.
The closest the antenna gets to the EIS is about 18 inches.
I presume your talking about the ANTENNA COAX
here . . . which should never be a factor
in preventing/fixing an EMC problem.
In the TC aircraft world, coax cables are
routinely routed in bundles with the most
vulnerable and antagonistic of wires
on the aircraft. The coax itself can
become problematic when it's improperly
terminated as discussed above.
Bob . . .
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billhuntersemail(at)gmail
Guest
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| Posted: Sat May 04, 2019 8:12 am Post subject: GRT EIS Issues When Transmitting |
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Bob,Â
As always I am grateful for your help.Â
I forwarded your response to my friend on the Velocity Owners Builders Association forum and encouraged him to join the aeroelectric list. A bunch of the VOBA guys are already here and I hope more will join up.Â
I will report back on what he discovered the problem was.
Thanks,
Bill Hunter
On Sat, May 4, 2019, 08:39 Robert L. Nuckolls, III <nuckolls.bob(at)aeroelectric.com (nuckolls.bob(at)aeroelectric.com)> wrote:
| Quote: | Greeting,
Â
I am posting for a friend who fly a Velocity?and I will get him to sign up for the Aeroelectric.
Â
His Question:
I need help with further troubleshooting an anomaly.
When I key the radio, all EGT & CHT temps drop about
25 degrees and stay there until the transmission is
released at which time they return to normal. This is
repeatable with the engine running or not. The EIS
has been replaced with a brand new one. I have swapped
radios on the antenna. Whichever radio is using
the stbd antenna causes the anomaly. I inspected
the antenna wire (RG-400) as much as possible without
removing it. No wear or nicks. System, both EIS and
radios have been flawless since installation in 2016.
  ALL instrumentation-grade electro-whizzies
  have SOME vulnerability to strong local
  radio energy. When design goals target
  installation in aircraft, the prudent
  designer will consider building
  a certain level of tolerance to radio
  energy. If the device is destined to
  fly in TC aircraft, then legacy qualification
  testing will have been conducted to verify
  the designer's successful achievement of
  design goals.
  I was unable to quickly locate any info
  on GRT claims for environmental robustness
  but they've been in the game for a long
  time. It seems likely that their products
  demonstrate adequate robustness to EM
  radiation.
  Further, the difficulty you're citing
  is a new condition which suggests a
  profound CHANGE in conditions between
  the antagonist/propagation-path/victim
  triad.
  As a general rule, electro-whizzies once
  demonstrated to meet design goals do
  not suddenly go "weak" with respect
  to electro-magnetic compatibility.
  This is why the FIRST line of investigation
  involves researching the propagation-path
  which generally consists of things 'hung
  out in the breeze' with respect to
  potential for damage or failure. The
  fact that one of two antennas is unique
  to the symptoms strongly suggests some
  CHANGE in the pathway between connector
  at the radio and the antenna itself.
  The first thing I do in these cases is
  check antenna SWR (and compare with
  other antenna). I think it likely that
  you'll find the 'bad' antenna has a
  much higher SWR. Damaged coax is the
  LEAST likely cause. Disconnection of
  either the center conductor or shield
  at the connectors is most likely.
  A very reasonable test tool for pursuing
  this investigation is seen here:
https://tinyurl.com/y64t9nse
[img]cid:.0[/img]
  (caution, there are both VHF/UHF and
   HF versions . . . get the VHF/UHF
   device)
  You'll probably also need a two-pak
  of these adapters:
https://tinyurl.com/y66wn6ua
  and a short BncM to BncM jumper cable
https://tinyurl.com/y3b7lvfp
Have even installed a ferrite sleeve on the cht/egt
wire bundle. No change. Transmission and reception
on the radio is loud and clear.
 Ferrite sleeves are marginally effective
 in meeting original design goals for
 EMC . . . we used to see these included in
 computer interconnect cables . . .
[img]cid:.0[/img]
 . . . but in the aviation world, they're
 considered an un-acceptable 'band-aid'
 to a problem that should be taken care
 of INSIDE the electro-whizzies. I don't
 even have such things in my inventory.
Â
I have a GRT EIS mounted [at the back of the copilot
side of the airplane] on the floor. The wires run through the
[fiberglass conduit] to the engine.
The closest the antenna gets to the EIS is about 18 inches.
 I presume your talking about the ANTENNA COAX
 here . . . which should never be a factor
 in preventing/fixing an EMC problem.
 In the TC aircraft world, coax cables are
 routinely routed in bundles with the most
 vulnerable and antagonistic of wires
 on the aircraft. The coax itself can
 become problematic when it's improperly
 terminated as discussed above.
 Bob . . .
|
| | - The Matronics AeroElectric-List Email Forum - | | | Use the List Feature Navigator to browse the many List utilities available such as the Email Subscriptions page, Archive Search & Download, 7-Day Browse, Chat, FAQ, Photoshare, and much more:
http://www.matronics.com/Navigator?AeroElectric-List |
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nuckolls.bob(at)aeroelect
Guest
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| Posted: Sat May 04, 2019 9:44 am Post subject: GRT EIS Issues When Transmitting |
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|
At 11:03 AM 5/4/2019, you wrote:
| Quote: | Bob,Â
As always I am grateful for your help.Â
I forwarded your response to my friend on the Velocity Owners Builders Association forum and encouraged him to join the aeroelectric list. A bunch of the VOBA guys are already here and I hope more will join up.Â
I will report back on what he discovered the problem was. |
Please do . . . My missives are always
based on best information I have at the
time . . . but that doesn't rule out
something-new-under-the-sun.
Would be pleased to know the outcome.
Bob . . .
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http://www.matronics.com/Navigator?AeroElectric-List |
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