AeroElectric-List Digest Archive

Wed 05/28/14


Total Messages Posted: 4



Today's Message Index:
----------------------
 
     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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    Time: 08:32:34 AM PST US
    From: "Robert L. Nuckolls, III" <nuckolls.bob@aeroelectric.com>
    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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    Time: 12:46:02 PM PST US
    From: Henador Titzoff <henador_titzoff@yahoo.com>
    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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    Time: 06:08:51 PM PST US
    Subject: Through-Hole Wire Metal
    From: "user9253" <fransew@gmail.com>
    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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    Time: 09:20:26 PM PST US
    From: MLWynn@aol.com
    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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