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Thermocouples connected to Dynon EGT CHT

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Sam

Joined: 18 May 2008
Posts: 135

Posted: Fri Nov 21, 2008 5:08 am Post subject: Thermocouples connected to Dynon EGT CHT

Please help me work through this.



1.  I am reusing my old Westach EGT/CHT thermocouples, type J & K.  They appear to be shielded and have 48" leads and will need new terminals.

2.  I have a pre-fab TC harness from Stein Air (for Dynon), which is made from a non-copper wire.  It seems to be pretty stiff.  The EGT lead wires, under the sheath, are rust/yellow.  The CHT wires are rust/white.  This harness wire is way too long and needs to be shortened.

 

My questions are:



A.  Due to the crazy airframe, it is not uncommon to pull the engine at annual inspection time.  What would be the best connector to use?  Could I use a D-sub? The connection to the D180 is a 25 pin D-sub.

 B.  For temperature accuracy purposes, would it be better to position the connector forward or aft of the firewall?  The most convienient would be forward.



Thanks, in advance.



Sam

www.samhoskins.blogspot.com

 [quote][b]

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Sam Hoskins
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rampil

Joined: 04 May 2007
Posts: 870

Posted: Fri Nov 21, 2008 8:58 am Post subject: Re: Thermocouples connected to Dynon EGT CHT

Hi Sam,



If you are talking about a connector on the firewall, use a metal

circular connector i.e., AMP. Do not use a a db submini for three

reasons: They are not deep enough to pass through most firewalls,

they provide no thermal insulation and are not rated for constant hi temp environment, and they are not gas tight against carbon monoxide etc.



AMP makes special pins for TC connections, but I have never seen

anyone ever use them.  Just live with the relatively tiny errors due to

the extra junction

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Ira N224XS

mrspudandcompany(at)veriz
Guest

Posted: Fri Nov 21, 2008 9:05 am Post subject: Thermocouples connected to Dynon EGT CHT

[quote]My questions are:



A.  Due to the crazy airframe, it is not uncommon to pull the engine at annual inspection time.  What would be the best connector to use?  Could I use a D-sub? The connection to the D180 is a 25 pin D-sub.

B.  For temperature accuracy purposes, would it be better to position the connector forward or aft of the firewall?  The most convienient would be forward.



Thanks, in advance.



Sam



                The 25 pin d-sub is a good choice.  Use the ones with the crimped pins, since soldering of thermocouple wires is not recommended.    You can use these forward of the firewall with very little degradation of accuracy.  The important thing with using a nonthermocouple material connector is that both sides of the connector should be at the same temperature, otherwise greater error will be introduced. Roger[b]

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nuckolls.bob(at)cox.net
Guest

Posted: Sat Nov 22, 2008 8:42 am Post subject: Thermocouples connected to Dynon EGT CHT

At 11:04 AM 11/21/2008, you wrote:



 	  Quote: 	
		  My questions are:



A.  Due to the crazy airframe, it is not uncommon to pull the

engine at annual inspection time.  What would be the best

connector to use?  Could I use a D-sub? The connection to the

D180 is a 25 pin D-sub.


	


    A d-sub with MACHINED crimped pins is fine.



http://www.aeroelectric.com/Pictures/Connectors/D-Subminature/D-Sub_20AWG_Pin.jpg



http://www.aeroelectric.com/Pictures/Connectors/D-Subminature/D-Sub_20AWG_Socket.jpg



http://www.aeroelectric.com/Pictures/Connectors/D-Subminature/D-Sub_4-quad-crimp.jpg



 	  Quote: 	
		  B.  For temperature accuracy purposes, would it be better to

  position the connector forward or aft of the firewall?

   The most convienient would be forward.


	


    Forward is fine. Just don't mount the connector

    THROUGH the firewall with an expectation of

    maintaining firewall integrity. I'd recommend

    you wrap the mated pair of connectors with silicone

    self-fusing tape to help keep them clean in service.

    These are NOT environmentally robust with respect

    to dirt, oils, etc.



    Alternatively, you could consider a mil-spec

    connector like the MS3470 series. These can be

    installed with the same crimp tool as the d-subs

    if you manually position the pins in the tool.

    But a mated set in low quantities will cost you

    about $50. The d-subs wrapped with silicone tape

    is the more economical.



    Effects on thermocouple readings will be

    small and insignificant.

        Bob . . .



        ----------------------------------------)

        ( . . .  a long habit of not thinking   )

        ( a thing wrong, gives it a superficial )

        ( appearance of being right . . .       )

        (                                       )

        (                  -Thomas Paine 1776-  )

        ----------------------------------------

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Iberplanes

Joined: 10 Dec 2007
Posts: 174
Location: Igualada - Barcelona - Spain

Posted: Sat Nov 22, 2008 10:16 am Post subject: Thermocouples connected to Dynon EGT CHT

si claro. Si Marta me deja sacar fotos pues lo haré, sino no pasa nada. Rercuerda que no tengo ganas de crear problemas ni mucho menos lastimar sentimientos de esta gente, que es bastante trajico todo. 



un abrazo

 



2008/11/21 rampil <ira.rampil(at)gmail.com (ira.rampil(at)gmail.com)>

 	  Quote: 	
		   --> AeroElectric-List message posted by: "rampil" <ira.rampil(at)gmail.com (ira.rampil(at)gmail.com)>

 

 Hi Sam,

 

 If you are talking about a connector on the firewall, use a metal

 circular connector i.e., AMP. Do not use a a db submini for three

 reasons: They are not deep enough to pass through most firewalls,

 they provide no thermal insulation and are not rated for constant hi temp environment, and they are not gas tight against carbon monoxide etc.

 

 AMP makes special pins for TC connections, but I have never seen

 anyone ever use them.  Just live with the relatively tiny errors due to

 the extra junction

 

 --------

 Ira N224XS

 

 

 

 

 Read this topic online here:

 

 http://forums.matronics.com/viewtopic.php?p=215559#215559

 

 

 

 

 

 

 

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-- 

Alberto Martin

www.iberplanes.es

Igualada - Barcelona - Spain



----------------------------------------------

Zodiac 601 XL Builder

 Serial: 6-7011



Tail Kit: Finished

Wings: Not Started

Fuselage: Ordered

Engine: Jabiru 3300

  [quote][b]

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601 XL - Jabiru 3300
http://www.iberplanes.es
Igualada - Barcelona - Spain

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