From: "Finn Lassen finn.lassen@verizon.net" <flyrotary@lancaironline.net>
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Subject: Re: [FlyRotary] Re: Update on EMI problem.
To: Rotary motors in aircraft <flyrotary@lancaironline.net>
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Date: Wed, 15 Jan 2020 15:47:33 -0500
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A ground issue somewhere. At battery, ground buss, ground strap to 
engine, ...
Corrosion or a loose bolt/nut.

Just guessing. But if it used to work and no changes were made before 
the symptoms appeared...

Yes, I know, easy to second guess the approach of someone else. :-)

Finn

On 1/15/2020 10:00 AM, Stephen Izett stephen.izett@gmail.com wrote:
> Hi Bobby
>
> I had no symptoms in the engine on tx until the last few weeks and only on controller A.
> It misses as the mixture goes very lean.
> In looking at the engine miss I realised the vertical speed was jumping on tx.
> Not sure what brought about the change that started the symptoms.
>
> Steve
>
>> On 15 Jan 2020, at 10:33 pm, Bobby J. Hughes bhughes@qnsi.net <flyrotary@lancaironline.net> wrote:
>>
>> Steve,
>>   
>> I don’t recall if you are just seeing odd instrument readings or actual engine changes when you key the mic. At idle and ground ops I could almost kill my engine when transmitting on an SL30. The capacitors eliminated 90% of that problem. When I swapped the SL30 for a 430W it improved a little more.
>>   
>> Bobby
>>   
>>   
>>   
>> From: Rotary motors in aircraft [mailto:flyrotary@lancaironline.net]
>> Sent: Wednesday, January 15, 2020 8:06 AM
>> To: Rotary motors in aircraft
>> Subject: [FlyRotary] Re: Update on EMI problem.
>>   
>> Hi Finn
>>
>> I only went for them as I understood others had suffered a similar symptom and this was Tracy’s recommended fix.
>> I’ve got more ferrites coming and I’ll be putting these on all inputs to the EC2 and ADHARS and at the feed point of the antenna.
>> I’ll feedback what I discover.
>>
>> Cheers
>> Steve
>>
>>> On 15 Jan 2020, at 9:02 pm, Finn Lassen finn.lassen@verizon.net <flyrotary@lancaironline.net> wrote:
>>>
>>> Did you trace the circuit? Any chance there's already caps on the board on your version of the EC2?
>>>
>>> Again, I don't see the need for the caps. Especially because your problem was only with controller A.
>>>
>>> I would start with temp input or serial input.
>>>
>>> Finn
>>>
>>> On 1/14/2020 11:23 PM, Stephen Izett stephen.izett@gmail.com wrote:
>>>> A frustrating few hours
>>>>
>>>> I got down to the hanger this morning to look into the EMI in both the engine controller and EFIS.
>>>>
>>>> First thing I did was reroute the radio coax so that instead of being in close proximity to many cables down the centre of the aeroplane instead down the very right hand side.
>>>> This increased the distance to various wire looms by ~450mm.
>>>>
>>>> Prior to this change the symptom outside the hangar was from memory about a 300ft/min vertical speed on tx in the Skyview EFIS.
>>>>
>>>> First test with radio tx after the reroute of coax inside the hangar yielded a "4 times worse" symptom in the EFIS! ~1300ft/min reading on tx.
>>>>
>>>> I then tried the test outside and away from the metal hangar by 10m and the symptom was reduced to ~600ft/min and increase in symptoms of about 100% on original problem.
>>>> I then applied a clamp on ferrite to the cable loom entering the ADHARS unit from where the symptom originates.
>>>> On tx outside the hangar again the symptoms are far reduced by over 1/2.
>>>>
>>>> So if I had left the radio coax where it was, the ferrite may have fixed the problem in the EFIS.
>>>> I have more ferrites on order and they appear to be very effective, so will use these to attenuate the RF entering the various pieces of equipment.
>>>> EMI trouble shooting is indeed a black art!!
>>>>
>>>> I also removed the Engine Control unit and soldered 0.1uF ceramics across the outputs to earth of the MAP sensors of both A and B computers as specified by Tracy.
>>>> On reinstalling the Engine Control unit I was not able to start the engine!
>>>> It would fire but not run on either controller.
>>>> So spark and fuel are present, but not to remain running.
>>>>
>>>> So the mod appears to have messed up the MAP sensing.
>>>> My initial thought was that the caps were actually resistors packaged wrongly but they measure open circuit.
>>>>
>>>> So the few hours of mods and testing has been exceedingly frustrating, going backwards at every turn except for the 1 ferrite showing itself to be very effective.
>>>>
>>>> I’m hoping my next outing will be very much more fruitful.
>>>> In the mean time I’ll ponder what could possibly cause both Computers in the Engine Controller to be u/s.
>>>> If I cannot discover my deliberate mistake. I’ll remove the caps and retest the Controller on Friday.
>>>>
>>>> Cheers
>>>>
>>>> Steve
>>>>
>>>>
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