---------------------------------------------------------- AeroElectric-List Digest Archive --- Total Messages Posted Sat 08/04/12: 3 ---------------------------------------------------------- Today's Message Index: ---------------------- 1. 06:13 AM - Re: Re: Extending thermocouple leads (Robert L. Nuckolls, III) 2. 01:28 PM - Starter contactor leaking voltage (Mickey Coggins) 3. 07:25 PM - Re: Extending thermocouple leads (Radioflyer) ________________________________ Message 1 _____________________________________ Time: 06:13:43 AM PST US From: "Robert L. Nuckolls, III" Subject: Re: AeroElectric-List: Re: Extending thermocouple leads At 01:51 PM 8/3/2012, you wrote: > >Bob, thanks for your reply. You asked what the spade terminals were >attached to. They are crimped on to the J wires of the thermocouple >sensor. The wires are red and white and one of them was magnetic. Do the terminals terminate to a 'sensor' under the cowl or to an instrument behind the panel? >You are right that a few degrees of error would not much matter for >CHT readings. I don't have a sense for how much error my >"J-spade-J-spade-instrument" setup would introduce, but if within >say ten degrees then it would be ok. I just want to be sure I can >reliably tell that my cylinders are not exceeding max allowable temperature. Sure. One way to check your instrument's calibration with as-installed thermocouples is to get one of those in-the-cup immersion heaters for travel-coffee/tea and use it to raise a cup of distilled or R/O water to boiling. You can do this right next to the engine where you've removed a cht sensor bulb and immerse it in the water. Wait several minutes while the reading stabilizes. Compare with boiling point of water at your present atmospheric pressure conditions: http://tinyurl.com/bmptwag and you can see just how close the instrument is to reading true at about 200F. Bob . . . ________________________________ Message 2 _____________________________________ Time: 01:28:38 PM PST US From: Mickey Coggins Subject: AeroElectric-List: Starter contactor leaking voltage Thanks Bob, Gents, for the feedback on this. I have done it the way the plans show, and you suggested, and put the starter contactor on the FW. New question (yes, I'm building very slowly) - I have the Van's starter contactor (Part Number = ES 24021) and when I apply 12v to the battery connection, I get about 0.4v on the starter connection. This is before it is energized. When I apply the 12v to the 'S' terminal, I get the full 12v on the starter terminal. Is it normal for some voltage to "leak" even when the device is "idle"? My battery contactors don't do this, and I don't have another starter contactor to test with. Thanks, Mickey ________________________________ Message 3 _____________________________________ Time: 07:25:16 PM PST US Subject: AeroElectric-List: Re: Extending thermocouple leads From: "Radioflyer" The extension (thermocouple) wire pair would eventually connect to an instrument on the panel in the cabin. So, Engine side: thermocouple--spades--J wire pair extension--thru firewall. Then Cabin side: extension cont'd--spades--copper--instrument on panel. The extension is 12 feet long because this is in a pusher aircraft. Spades to copper to instrument because I can't connect the J type thermocouples wires directly to the DB15 on the instrument. What I'm thinking is that the parasitic couple between spades and thermocouple wire pair in the hot engine side, and the other parasitic couple of thermocouple wire pair and spades in the cooler cabin will not much affect the absolute temp readings. --Jose Read this topic online here: http://forums.matronics.com/viewtopic.php?p=380062#380062 ------------------------------------------------------------------------------------- Other Matronics Email List Services ------------------------------------------------------------------------------------- Post A New Message aeroelectric-list@matronics.com UN/SUBSCRIBE http://www.matronics.com/subscription List FAQ http://www.matronics.com/FAQ/AeroElectric-List.htm Web Forum Interface To Lists http://forums.matronics.com Matronics List Wiki http://wiki.matronics.com Full Archive Search Engine http://www.matronics.com/search 7-Day List Browse http://www.matronics.com/browse/aeroelectric-list Browse Digests http://www.matronics.com/digest/aeroelectric-list Browse Other Lists http://www.matronics.com/browse Live Online Chat! http://www.matronics.com/chat Archive Downloading http://www.matronics.com/archives Photo Share http://www.matronics.com/photoshare Other Email Lists http://www.matronics.com/emaillists Contributions http://www.matronics.com/contribution ------------------------------------------------------------------------------------- These Email List Services are sponsored solely by Matronics and through the generous Contributions of its members.