Sender: <marv@lancaironline.net> (Marvin Kaye)
To: lml@lancaironline.net
Date: Fri, 31 Oct 2003 01:42:08 -0500
Message-ID: <redirect-2704031@logan.com>
From: "F. Barry Knotts" <bknotts@buckeye-express.com>
Subject: Dynon EFIS EMI
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Marv...
picked this up from a friend of a friend.  Beta testing continues, as it
should.

I haven't bought any avionics yet.  I feel like I've made the best
choice so far. 

Barry Knotts
LIV-P, Conti-TSIO 550, 20% Toledo, Ohio

-----Original Message-----
From: Tom Walsh [mailto:duckquack4@earthlink.net] 
Sent: Thursday, October 30, 2003 10:18 PM
To: bknotts@earthlink.net
Subject: Re: Dynon EFIS EMI


This email was sent to you by Tom Walsh at duckquack4@earthlink.net
because they thought you might be interested in this article from
http://go.phpwebhosting.com/~khorton/rv8.  This is not SPAM and the
email addresses involved in this transaction were not saved to a list or
stored for later use. Tom Walsh wrote: Barry, 
Saw this on EMI the Dynon D10. Sent it to you and Tony since we are all
probably going to use the D10. Tom
------------------------------------------------------------

Dynon EFIS EMI
Sunday, 26 October 2003 @ 20:49 EST
Contributed by: kwh

It seems that Dynon is fighting an electro-magnetic interference problem
(EMI).  Hopefully it won't be too hard for them to solve.  The following
message was posted on the RV-List (the first part is a question from a
list-member - the second part is a response from Sam Buchanan):

>>I recently flew my RV7 from Fl to Spokane and back and still
>>love my Dynon D-10. I do however have a problem that concerns 
>>me: the D-10 emits enough RFI to render the VOR/LOC receiver 
>>inoperative unless within approx 7 miles of the station. The 
>>VOR voice is nothing but static. Turning the D-10 off 
>>rectifies the problem and the VOR will receive up to 100 NM 
>>away. I have a wingtip mounted VOR antenna.
>>
>>Dynon said they have had several complaints on this problem
>>and are working on it. I was wondering if anyone on the list 
>>has had a similar problem and fixed it and if so how.

Yes, I have been dealing with the EMI issue with the Dynon. Like you, I
am very impressed with the D-10, but the initial install was a bit
challenging. One problem had to do with a bad magnetometer and has been
successfully resolved. The other issue which is still present but now
very manageable, is the EMI emitted primarily via the EDC remote
magnetometer serial connection. I doubt that antenna location, radio
stack location and other such physical items are going to have much
impact on whether or not EMI is present in a particular Dynon
installation.

It appears the EDC is transmitting considerable RFI back up to the D-10
via the EDC power feed. The noise then is passed along by the D-10 out
the main power and keep-alive feeds to the avionics bus. EMI is a very
strange and unpredictable animal that often flaunts logic. In my case,
the noise was very noticeable through the com radio, even to the point
of often breaking the squelch. But, it wasn't consistent; even though
always present, it varied depending on the frequency in use, the time
zone I was in, and what I had eaten earlier in the day. In other words,
there was little pattern to the madness. The nav side of the radio was
completely unaffected.

After some basic troubleshooting (disconnecting the EDC while the D-10
was running) it was determined that the EDC was indeed the culprit. Doug
at Dynon was working through the problem and suggested I power the EDC
via a different point on the avionics bus. That I did, and the noise was
drastically reduced. As a part of Dynon's troubleshooting, I also
installed some capacitors in the D-10 and the EDC and that lowered the
noise level a bit more.

Bottom line, at this point in time there is still a very low amplitude
noise in the my com radio which is only noticeable when receiving very
weak signals. The separate power feed for the EDC "solved" most of the
EMI problem. But the Dynon guys realize this is not a true solution
since now the remote mag is isolated from the back-up power features of
the D-10, and the EMI is still being generated. Also, the separate power
feed can create some weird issues when using the support program to
customize the EFIS. It is necessary to interrupt the power to the EDC
when the D-10 is rebooted or the support program can hang since the EDC
is still in a "Loader" mode.

I suspect there are many Dynon installations that have the noise issue
but the builder doesn't know because the source of the noise is buried
in the chaos of getting a new panel up and running and the builder is
chasing all sorts of shielding ideas trying to figure out where the
static is coming from. By the way, one of the first steps I took was to
replace the CAT-5 cable I was using for the remote mag with
four-conductor shielded cable, but that had no impact on the problem. I
also shielded the main EFIS power cable but that likewise had no impact.


So shielding does not seem to be the answer, and the EMI bug will affect
some installations and not others until Dynon gets a handle on the
problem. If nothing else, the remote mag can be disconnected and the
"problem" goes away (along with a *very* accurate heading indicator if
the mag installation is carefully done!).

In my opinion, this in no way should be a discouragement to buying a
Dyon EFIS. The unit works as advertised, and I am very confident the
Dynon crew will squash this bug and do what is right to rectify the
situation for those who find it necessary.


John, try the separate power feed for the EDC and your nav will probably
again be usable. Sam Buchanan 


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