Today's Message Index:
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1. 08:32 AM - Re: Trio Avionics ProPilot 130 Mhz interference problem (was noise problem on radio) (Robert L. Nuckolls, III)
2. 12:46 PM - Re: Trio Avionics ProPilot 130 Mhz interference problem (was noise problem on radio) (Henador Titzoff)
3. 06:08 PM - Through-Hole Wire Metal (user9253)
4. 09:20 PM - testing a coax lead (MLWynn@aol.com)
Message 1
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Subject: | Re: Trio Avionics ProPilot 130 Mhz interference problem |
(was noise problem on radio)
At 05:33 PM 5/27/2014, you wrote:
>Glad to hear you solved your problem, Sacha. So much for vendors
>meeting standards like DO-160G. This Trio product is designed
>incorrectly to meet this standard, and their switching frequencies
>to move it away from 130.00 MHz is only a band-aid.
>
>We had a discussion earlier about how an open antenna cable could
>cause damage to a transmitter, and I explained how the wave's
>voltage can double as it bounces back to the transmitter. Bob said
>that today's avionics are protected against such damage. I claim
>not all electronics are designed to DO-160 and if they are,
>sometimes engineers make mistakes or the product is manufactured
>incorrectly. As Bob said, it's a very small probability but it can happen.
We're talking about two different critters here . . .
DO-160 is not a requirement but a validation guide
for design goals. It's sorta like the covenants you
sign with the homeowner's association that says you
both understand and agree to certain behaviors. It
gives you and your neighbors a level of confidence
for friendly co-existence in a close knit community.
Wrapping SWR protection around the final amplifier
of a transmitter is a common sense recognition of
risk followed by a behavior to design for SWR robustness
-or- automatic reduction of drive to the final amplifier
when excessive SWR is detected. Both approaches have been
part of the best we know how to do for decades. Neither
one is difficult. For writers in technical matters
to make blanket statements warning against test
operations into open transmission lines suggests
that they simply choose not to avail themselves
of pretty common knowledge. Consider the hand-held
transceiver that can be keyed into a constellation
of antennas presenting SWR values the hand-held
designer has no control over . . . but it's no
big deal . . . protection against such hazard
is rudimentary to the contemporary design process.
Not designing around the risks for high
SWR is like opening the hood of a modern car
to find a carburetor sitting on top of the engine
. . . everybody looks at each other and asks
"why would anyone do that?"
On the other hand, my first contact with Trio
suggests that they've treated DO-160 as a 'requirement'.
Given that they do not sell into the TC aircraft
market, they seem to think DO-160 is not applicable/
useful to their design efforts.
I'll see if I can help them deduce the
feature of their product that lets the interfering
energy get outside their box . . . and hopefully
there is a relatively painless solution. We'll
see. It would be useful for them -AND- their
customers to understand that DO-160 guidelines
are recipes for blissful living in the
community of airplane owners no matter where
the airplane was built.
Bob . . .
Message 2
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Subject: | Re: Trio Avionics ProPilot 130 Mhz interference problem |
(was noise problem on radio)
Thanks, Bob, for understanding that DO-160 is a verification standard that
lists and specifies requirements for:=0A* temperature effects=0A=0A*
altitude effects=0A=0A* humidity effects=0A=0A* shock and vibration e
ffects=0A=0A* explosion susceptibility and water proofness =0A=0A* fl
uids susceptibility, sand and dust intrusion=0A* fungus resistance=0A
* salt and fog resistance=0A* magnetic effect on ship compass=0A* pow
er input variations effects=0A=0A* voltage spike effects=0A=0A* audio
frequency conducted susceptibility=0A* RF susceptibility and emissions
=0A* lightning susceptibility=0A* icing effects=0A* ESD susceptibi
lity=0A* flammability analysis=0ASince the above parameters are verified
, it stands to reason that the avionics designer must design for them in or
der to pass the DO-160 standard.- In Trio's case, they violated RF emissi
ons requirements.=0A=0AIf you do talk to them, please note that the most li
kely culprit is the PCB design.- Proper design here will contain the ener
gy that leaks out the sides of the board and also- minimizes radiated RF
energy by using microstrip and stripline designs.- There are tools such a
s Mentor Graphics Hyperlynx that can simulate the design and thus minimize
it by offering standard solutions as well as making changes and iterating t
he simulation to see what effect the change made.- I've seen designs go f
rom obnoxiously loud to very quiet by using proper design techniques and si
mulation. =0A=0A=0AHenador Titzoff=0A=0A=0A>_______________________________
_=0A> From: "Robert L. Nuckolls, III" <nuckolls.bob@aeroelectric.com>=0A>To
: aeroelectric-list@matronics.com =0A>Sent: Wednesday, May 28, 2014 11:29 A
M=0A>Subject: Re: AeroElectric-List: Trio Avionics ProPilot 130 Mhz inter
ference problem (was noise problem on radio)=0A> =0A>=0A>=0A>At 05:33 PM 5/
27/2014, you wrote:=0A>=0A>Glad to hear you solved your=0Aproblem, Sacha.
- So much for vendors meeting standards like=0ADO-160G.- This Trio prod
uct is designed incorrectly to meet this=0Astandard, and their switching fr
equencies to move it away from 130.00 MHz=0Ais only a band-aid.=0A>>=0A>>We
had a discussion earlier about how an open antenna cable could cause=0Adam
age to a transmitter, and I explained how the wave's voltage can=0Adouble a
s it bounces back to the transmitter.- Bob said that today's=0Aavionics a
re protected against such damage.- I claim not all=0Aelectronics are desi
gned to DO-160 and if they are, sometimes engineers=0Amake mistakes or the
product is manufactured incorrectly.- As Bob=0Asaid, it's a very small pr
obability but it can=0Ahappen.=0A>-- We're talking about two different
critters here . . .=0A>-- DO-160 is not a requirement but a validation
guide=0A>-- for design goals. It's sorta like the covenants you=0A>-
- sign with the homeowner's association that says you=0A>-- both unde
rstand and agree to certain behaviors. It=0A>-- gives you and your neig
hbors a level of confidence=0A>-- for friendly co-existence in a close
knit=0Acommunity.=0A>=0A>-- Wrapping SWR protection around the final am
plifier=0A>-- of a transmitter is a common sense recognition of=0A>-
- risk followed by a behavior to design for SWR=0Arobustness=0A>-- -o
r- automatic reduction of drive to the final=0Aamplifier=0A>-- when exc
essive SWR is detected. Both approaches have=0Abeen=0A>-- part of the b
est we know how to do for decades. Neither=0A>-- one is difficult. For
writers in technical matters=0A>-- to make blanket statements warning a
gainst test=0A>-- operations into open transmission lines suggests=0A>
-- that they simply choose not to avail themselves=0A>-- of pretty
common knowledge. Consider the hand-held=0A>-- transceiver that can be
keyed into a constellation=0A>-- of antennas presenting SWR values the
hand-held=0A>-- designer has no control over . . . but it's no=0A>-
- big deal . . . protection against such hazard=0A>-- is rudimentary
to the contemporary design process.=0A>-- Not designing around the risk
s for high=0A>-- SWR is like opening the hood of a modern car=0A>--
to find a carburetor sitting on top of the engine=0A>-- . . .- every
body looks at each other and asks=0A>-- "why would anyone do that?"=0A>
=0A>-- On the other hand, my first contact with Trio=0A>-- suggests
that they've treated DO-160 as a=0A'requirement'.=0A>-- Given that the
y do not sell into the TC aircraft=0A>-- market, they seem to think DO-
160 is not applicable/=0A>-- useful to their design efforts.=0A>=0A>-
- I'll see if I can help them deduce the=0A>-- feature of their produ
ct that lets the interfering=0A>-- energy get outside their box . . . a
nd hopefully=0A>-- there is a relatively painless solution. We'll=0A>
-- see. It would be useful for them -AND- their =0A>-- customers to
understand that DO-160 guidelines =0A>-- are recipes for blissful livi
ng in the=0A>-- community of airplane owners no matter where=0A>--
=========== =0A>=0A>
Message 3
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Subject: | Through-Hole Wire Metal |
Some resistors and capacitors have tinned copper leads and some have steel leads.
Does it matter? It seems to me that copper is better because it does not
rust. What do you think?
Joe
--------
Joe Gores
Read this topic online here:
http://forums.matronics.com/viewtopic.php?p=423932#423932
Message 4
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Subject: | testing a coax lead |
Hi folks,
I am about to fly my RV 8 for the first time. Finished construction and
am now tracking down glitches. I had a guy out to certify my pitot, static
and transponder today. Pretty funny sequence. First, we couldn't get
altitude data to the transponder. Turns out that you have to turn on the
serial data feed in a GRT EFIS. Next, turned out the feed pin on was sub-D
connector into the transponder was in the wrong spot. Finally got a read-out
on the altitude. Last problem, the transponder signal was really weak.
We disconnected the antenna and plugged the transponder directly into his
tester. The unit, a Garmin 327, was working fine. That leaves the
antenna and leads.
I used a right angle adaptor as described in the comic book. One from the
transponder and one into the antenna. Seems highly unlikely that there is
a break in the cable itself. More likely, one of the connectors or the
right angle adaptors is at fault.. Any good ideas about how to test this? I
don't want to have the certification technician come out again until I am
sure I have solved the problem. I also don't want to tear out the entire
cable and start over--really inconvenient at this juncture. I didn't leave
enough slack to cut off the connecters and start over so really, I just
need to diagnose the location of the fault and repair it.
Two questions: how to track down the fault; how to test the line and/or
antenna to make sure it is functioning properly prior to calling out the
technician again.
Suggestions?
Regards,
Michael Wynn
RV 8 Finished
San Ramon, CA
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