From: "Stephen Izett stephen.izett@gmail.com" <flyrotary@lancaironline.net>
Received-SPF: pass
 receiver=logan.com; client-ip=209.85.216.41; envelope-from=stephen.izett@gmail.com
Content-Type: text/plain;
	charset=utf-8
Content-Transfer-Encoding: quoted-printable
Mime-Version: 1.0 (Mac OS X Mail 12.4 \(3445.104.11\))
Subject: Re: [FlyRotary] Re: Gremlin Search
Date: Mon, 6 Jan 2020 15:55:53 +0800
References: <list-13368018@logan.com>
To: Rotary motors in aircraft <flyrotary@lancaironline.net>
In-Reply-To: <list-13368018@logan.com>
Message-Id: <1D96CA42-D660-4055-B489-5839654D529F@gmail.com>

Hi Bobbly and Andrew

Thanks for the feedback guys.

I was just surprised as it had been fine previously. I=E2=80=99ll =
retrace some of my steps and see if I can pin point the culprit, I am =
afraid these can be a really curly problem to fix.

Cheers

Steve


> On 6 Jan 2020, at 11:18 am, Andrew Martin andrew@martinag.com.au =
<flyrotary@lancaironline.net> wrote:
>=20
> Hi Steve
> I feel your pain, I had similar to your No.1 problem a few years ago, =
had RF getting into CAS wire, was really hard to trace as only happened =
in flight and scared the crap out of me every time I had to go up and =
test for it, as motor would stop on each TX, ended up just being the =
quality of CAS wire I used was not up to the job. I had tried all sorts =
of things prior to this with no avail, replacing the CAS wire with =
industrial sized Beldon shielded cable was a last ditch effort before =
completely rewiring the plane, luckily it worked. Mixture was affected =
by the RX getting in the CAS wire. I just cant remember if it was going =
extreme lean or rich as at that stage I didn't have the wideband AFR =
gauge installed.
>=20
> Andrew
>=20
>=20
>=20
>=20
> On Mon, Jan 6, 2020 at 10:40 AM Stephen Izett stephen.izett@gmail.com =
<flyrotary@lancaironline.net> wrote:
> Hi Guys
>=20
> I wonder if you guys have come across this fault or can help with my =
search for the culprit.
> Having made some alterations to our Dynon Skyview EFIS we went to fly =
only to have a problem and so aborted the flight.
> Previously the engine has been rock solid with none of the new =
symptoms.
> I have an Electronics/Communication systems background.
>=20
> The problem/symptoms:
>         1. During taxiing we noticed that every time we keyed the mic =
of the Garmin GTR225 we experienced significant mixture variations and =
stumbling of the Engine (Renesis 4 Port - EC2)
>         2. We then sought to clearly establish the symptoms and =
discovered that along with the very repeatable interference to the =
Engine/EC2, the Skyview EFIS was also effected by tx. The vertical speed =
would go +250ft/min then -100ft/min on keying the mic.
>=20
> The changes we had made:
>         1. Changed the Pitch Autopilot Servo to a heavier duty unit =
(no wiring change)
>         2. Installed the Dynon Auto Pilot & Knob Panels - this meant a =
new connection to the the Skyview bus and shifting the trim control =
(inputs from sticks, Power and output to Electric Trim motor) from a =
relay deck to the Dynon AP Panel (Build in trim controller).
>=20
> My thoughts are two fold:
> 1. RF getting into somewhere it shouldn=E2=80=99t. No changes have =
been made to the antenna or feed. However, I may have shifted some =
cables in close proximity to the antenna coax. I had just washed and =
left wet the Glasair's (fibreglass) vertical fin which has the 1/4 wave =
dipole antenna inside of it.
> 2. Earthing issues. There were no changes to the Earth system.
>=20
> Path forward:
> 1. Replace antenna feed with dummy load to isolate RF while still =
drawing current from the GTR225. (Where to borrow a dummy load around =
here?)
> 2. Check wiring to see if it is apparent that some have shifted in =
relationship to the antenna coax.
> 3. Check Earth buss for good connections.
>=20
> I do recall hearing someone with a similar fault on an EC2/3 years =
ago.
>=20
> Would really appreciate your feedback. I have little experience with =
RF interference and its rectification(no pun intended).=20
>=20
> Sincerely
>=20
> Steve Izett
> Perth Western Australia - Glasair Super IIRG - Renesis 4 Port EC2 EM3 =
RD1C
>=20
>=20
>=20
>=20
> --
> Homepage:  http://www.flyrotary.com/
> Archive and UnSub:   =
http://mail.lancaironline.net:81/lists/flyrotary/List.html