Connectors for PT100s?

I use PT100s as my controlers temperature sensors, 2 wire Class A from China and I've found then to be very linear if I get a reading of 2°C at zero then I get 102°C at the boil.

I'm having problems with the connectors, I've tried phono plugs, mini xrf and now gold plated banana plugs. I'm not happy with them they all seem to introduce inconsistent resistance and/or not last.
I want to be able to calibrate and auto tune my system knowing that if I disconnect and reconnect a sensor it will still be right.

I've yet to try RJ45 connectors or screw strip connectors (chock blocks) can you recommend anything better?

Thanks. Aamcle

To solve your problem, I look at other signals that have similar requirements to your RTD-100. The answer I see is the microphone connection.Start with the good old fashion XLR connector. They have been used to connect microphine level signals for decades. Mechanically robust, easy to terminate properly and can accomidate a variety of cables. Nuetrik brand enjoys a reputation of making high quality XLR connectors.

For cables, the popular "best" cable among pro-audio is the star-quad design. Every maker of microphone cables has their own version of this design. It is low capacitance, low inductance, low impedance, low yada-yada, high noise imunity, high CMMR, high blah-blah, etc. Star-quad cable is available from a variety pro-audio distributors and can be purchased by the foot. If your star-quad experiment turns out not to be an improvement, it will not be such an expensive experiment.

If you go with Neutrik XLR and star-quad cable, You have (from a practical standpoint) maxed out on cable/connection perfomace.

RJ45. I do not understand why so many important connections use the RJ45. Your connection relies on the bent wires in the female connector and the plastic clip on the male connector. IMHO - It has no place in a home brewers system. Save a literal network (IP style) connection.

A second choice is a DB style connection. It is mechanically sound, the pin-to-pin connection is solid. You can terminate a DB connection using a solder cup, so doing a proper job is not difficult. Plus the connectors are cheap and the density of conections is attractive.

There are other esoteric connectors available. Lemo, Switchcraft, Tyco, Amphenol, etc make various types of connections. Same goes for cables. There are high end performance cables available. I seriously doubt any of these theoreical improvements will translate into more accuracey on your PID display. IMO, not worth the expense and trouble.

Thanks Rufus.

Aamcle

Omega makes a lot of thermocouple and RTD connectors and parts:

http://www.omega.com/section/thermo...-system.html?gclid=CMPjo6DdgMcCFSTncgodJAgOiA

Probably already knew this but you have to match the materials of the cable conductors to the connectors/plugs etc.....

I don't consider $3 each too bad.

For the big $$ stuff check out their sanitary style stuff.

burnthesheep said:

Probably already knew this but you have to match the materials of the cable conductors to the connectors/plugs etc....

Click to expand...

For thermocouples yes, RTDs no. You can use pretty much any connector for RTDs.

I have an Omega PID as it happens, I think I'm going to abandon elegance and go with good old ugly screw connectors.

Aamcle