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Date: Fri, 18 May 2007 10:24:46 -0600
From: Bob White <rlwhite@comcast.net>
To: "Rotary motors in aircraft" <flyrotary@lancaironline.net>
Subject: Re: [FlyRotary] EC2 probe grounding.
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Hi Dave,

Why not use the sensor Tracy provides with the unit?  All of them I've
seen are two wire and Al's description of the connections are correct.
The EM2 comes with a 3 wire OAT sensor.  Some very early EC2's may have
had a 3 wire sensor but Tracy would have to confirm that.

Bob W.


On Fri, 18 May 2007 00:06:28 -0500
David Staten <Dastaten@earthlink.net> wrote:

> Just pinging the group on this.
> 
> Chris (and every once in a while I) are to the stage of wiring up 
> goodies to the EC2. We have the injectors, resistors and most of that 
> stuff done. Next is the inlet air temp sensor for the EC2 (to be 
> followed by all the other sensors for the EM2).
> 
> There are two wires for the EC2 air temp sensor. There are conflicting 
> instructions and diagrams with regards to a new and old scheme that 
> involve 2 of 3 possible pins on the plug (I think it was 1, 11 and 31, 
> but not positive - you can look at the EC2 diagrams regarding this.
> 
> Anyways, the VDO air temp probe I am using is a 1/8" NPT 300 degree F 
> with a terminal on top that can receive a female spade connector.
> 
> The top terminal is clearly insulated from the rest of the probe, and 
> the body of the probe is the ground.
> 
> What is the best method for wiring this type of probe.. obviously one 
> wire to the top terminal, the positive if so designated. But do we put a 
> ring terminal on the body of the probe and hook up the second EC2 wire 
> to it? Or do we consider the engine block the ground, which the intake 
> will be firmly attached to, and connect the second wire to our forest of 
> tabs grounding block on the firewall.
> 
> It seems that grounding the probe with a ring terminal can introduce a 
> ground loop because now there are two potential paths back to the EC2. 
> Are the air temp leads electrically isolated (transformer coupled, for 
> instance) or is a ground loop possible.
> 
> More than anything else, I would like to hear from those of you who are 
> flying with the EC2, because at this point I need practical, not 
> theoretical help. I know Tracy is off the grid, so I may wait a while to 
> hear from him, but the rest of you with EC2 rotary time, please tell me 
> how your set-up is set up.
> 
> Dave (and Chris)
> 
> --
> Homepage:  http://www.flyrotary.com/
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