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  #1  
Old 02-08-2021, 09:42 PM
Sam_B Sam_B is offline
 
Join Date: Apr 2016
Location: Boyceville, Wi
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Default Thermocouple wire

Hello all, Iím working on wiring the FWF stuff. From what Iíve been seeing, it doesnít seem like a lot of the thermocouple extension wire out there is shielded. Seems like the engine compartment would be an electrically noisy place with alternators and ignition systems, and thermocouples run down in the micro volt range IIRC. Have people been using shielded thermocouple wire, and if so where do you buy it?

Chances are Iím uninformed about something, so if there is no shielding, can someone explain why?

Thanks,
Sam
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  #2  
Old 02-08-2021, 10:02 PM
BobTurner BobTurner is online now
 
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Location: Livermore, CA
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Because all the probes have some ‘thermal inertia’, their outputs are nearly dc signals. It’s easy to design thermocouple amplifiers that reject ac signals.
Edit. Also, just keeping the two wires twisted together produces a large amount of ‘shielding’; signals induced on both wires tend to be identical, and are easily rejected by the amplifier.

Last edited by BobTurner : 02-08-2021 at 10:11 PM.
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  #3  
Old 02-08-2021, 10:03 PM
00Dan 00Dan is offline
 
Join Date: Nov 2016
Location: Atlanta
Posts: 102
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Iím installing a JPI right now and as I understand the manual and speaking to others whoíve done it, apparently the strategy is simply strategic routing of the harness to avoid the starter, alternator, and ignition wiring.
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  #4  
Old 02-09-2021, 07:52 AM
DennisRhodes DennisRhodes is offline
 
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," and if so where do you buy it?"

OMEGA is a large warehouse and on line supplier of about all Thermocouple types and supplies. They are commercial and industrial but their products are totally compatible.

https://www.omega.com/en-us/temperat...B&gclsrc=aw.ds
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Last edited by DennisRhodes : 02-09-2021 at 07:55 AM.
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  #5  
Old 02-18-2021, 10:33 PM
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RV7A Flyer RV7A Flyer is offline
 
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Quote:
Originally Posted by DennisRhodes View Post
," and if so where do you buy it?"

OMEGA is a large warehouse and on line supplier of about all Thermocouple types and supplies. They are commercial and industrial but their products are totally compatible.

https://www.omega.com/en-us/temperat...B&gclsrc=aw.ds
And ditch the insulated tongue-and-spade connectors that the probes usually come with, replace with the Omega mini-connectors. Designed for thermocouple wires. Changed mine out a while back and have been very happy with them so far (knock on wood). The crimped connectors seem to have a knack for loosening on the solid wire and once they do that, it's a booger to get them to ever work right again.

Be sure to get the right connectors for the wire type...J or K (different colored connectors for each)...in the small (mini) size.
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