Rework of EGT thermocouple wiring

Previously I transitioned the Type K EGT thermocuple wires to copper wires at a terminal block mounted on the firewall. This chromel/alumel transition to copper places the cold termperature reference forward of the firewall where the temperatures will be elevated. Given that the Dynon EMS220 has a cold-junction-compensation thermistor within the box, this means that whatever the temp difference at the terminal block and this thermistor, then the presented EGT readings will contain this uncorrected error.

This is clearly not best practise, so I have decided to go down the proper path of extending the thermocouple wires with type K extension lead all the way to the EMS220. I am also dumping the 8 x 2 screw terminal block as a means of transition, as this is a source of mechanical/electrical unreliability due to potentially loosening screws and lack of environmental protection. It also is a source of error due to the chromel/alumel - copper - chromel/alumel transitions. Any temperature gradient across the terminal block will introduce error if one wire is fastened under one screw and the connecting wire is fastened under the other screw. This particular error can be eliminated of the solid wires (the 2,5mm pins on the supplied thermocouples will be cut off) of the thermocouples are wrapped ("wrapped method") around the stranded (7/0.2mm) wires of the extension leads and then clamped. This takes the copper out of the thermoelectric equation. However for the other reasons I am getting rid of it.

Alternative connection methods under consideration include crimping

https://www.dwyeromega.com/en-au/crimp-style-thermocouple-pin-socket-contacts-hollow-core/p/HPC-CONTACTS

but these are super expensive

Alternatively the use of crimpable copper hollow barrels, using the wrapped method might be an option, such as the TE Solistrand range butt splices

https://www.te.com/en/product-2-31818-1.html

Alternatively, the use of OLC-2 connectors, using the wrapped method

https://www.aircraftspruce.com.au/catalog/pnpages/10-54070.php

although there is the concern about screws loosening or cutting into the wires

Alternatively, the use of type K mini-connectors

https://oztherm.com.au/collections/mini-connectors/products/thermocouple-flat-pin-mini-connectors-with-metal-cable-clamp?variant=40435555008684

https://oztherm.com.au/collections/mini-connectors/products/thermocouple-flat-pin-mini-connector-socket-with-cable-clamp

The Type K extension cable should be the teflon type, not fiberglass

https://oztherm.com.au/collections/k-type-thermocouple-cable-1/products/copy-of-k-type-thermocouple-grade-cable-fibreglass-insulated

and the same is true of the sensors themselves, due to resistance to moisture absorption

https://oztherm.com.au/collections/general-purpose-thermocouples/products/k-type-ptfe-teflon-insulated-thermocouple-sensor-250-c?variant=40849581867180

However I had previously purchased fibreglass insulated patch sensors for the battery and regulator monitoring, so will cut the leads of these short and transition to teflon after only a short distance

https://oztherm.com.au/collections/general-purpose-thermocouples/products/k-type-patch-thermocouple-250-c-fast-response