10 Pieces 3 Meters K Type Mini-Connector Thermocouple Temperature Probe Sensor K Type Thermocouple Wire Temperature Sensing Line Measure Range -50 to 400 Celsius, Compatible with TM902C/ TES1310

I bought these because one of my multimeters has a temperature measurement function and uses K-type thermocouples with this type of plug. I only had one thermocouple for it and, though I rarely use it, I don't like the idea of being without it if the thermocouple breaks. Sometimes an infrared thermometer just isn't good enough and you need to stick an actual thermocouple onto what you're measuring. I received the set of 5 and plugged them in. All of them seemed to read the ambient temperature in my garage (65ish degrees F) correctly. All of them heated up to 80-something degrees between my fingertips. That was the extent of measuring that I did so I can't vouch for their accuracy. A better way to do this is to measure boiling water (212F at sea level) and ice (0F). These two data points should tell you if things are relatively close, or at least if something is drastically wrong. For bonus points, you can measure the temperature of other cooling baths to get more data. Something like acetone and dry ice (-108F) or liquid out of an air duster can (roughly -4F to -12F for difluoroethane) will give you some interesting data points. Someday I might do that. Not too long ago I'd probably have been buying these things from Omega Engineering or someplace similar. The quality would have been good but I would've paid more for one thermocouple from them than I paid for all five of these. For non-critical measurements, having inexpensive ones like this around is fantastic.

I use these for measuring everything from heated floors and HVAC systems to 3D printer bed temperatures with my Agilent and Siglent DMMs. I have not had any issue with the probes. They seem accurate (as accurate as any K-type thermocouple) and are well made. With the 5 supplied, these should last me for many, many years.

This may be nit-picky, but the photo shows the thermocouples wrapped in a circle. When you get them they are neatly packaged in a folded "hank", as is common with most cords for electronics. Why does it matter? I have used these for years. No matter how careful you are, unfolding and straightening the wires, they want to get a tight kink in them, exactly where they were previously folded for packaging. That shortens their life. Considering the reasonable price, and good temperature resistance, I guess they last long enough. Accuracy is good for the price. Not calibration grade, but good for almost all but the most demanding measurements.

If you've worked with these kinds of sensors at all you know they are fragile as heck. I had one that came with an expensive multimeter fail out of the box. I bought these to verify the problem was the probe and not the meter itself. Plugged it in and got nearly instant readings. Temp readings were accurate. By buying this bulk pack now I have some in reserve for when another one breaks. Side note - How these devices work is by using two dissimilar metal wires which are soldered or bonded together at the probe end. When the dissimilar metals are exposed to changing temperatures they create an electrical reaction which a meter can measure. The wires are tiny, and if exposed to a lot of mechanical stress they will separate electrically (i.e. break) which causes the probe to fail or become unreliable. Just FYI.

We have a very old TC welding machine that we used to make Thermo Couples. It works well and is very handy. I purchased these TCs as a test to see if we could use purchased TCs, if our welder failed. The purchased TCs from this vendor are equal in every way to those we make. I compared the temperature reading with a quality Fluke, handheld meter. The TCs we make (that I trust) read identical to those from the vendor. The only question might be the quality of the insulation. I say “question” because I have not tested the resistance to burning of their fiberglass insulation but it appears to be authentic fiberglass sheathing. I will test heat resistance and update this post.

Good affordable product.

The whole reason I bought this particular set of probes is because they are pictured as being rolled into round loops rather than tightly kinked. That is the proper way to roll wires so the sheath doesn't break down and so the wire inside is not weakened by sharp bends. The probes I received are NOT rolled like in the picture - they are tightly kinked and break easily at those sharp kinks. JUNK! Why not roll them up like in the picture? The first wire broke within minutes of trying to use it - I returned them to Amazon.

They were initially flaky. It seems to work okay once I untwist the end near the welded ball. Based on one video I saw, twisting the two bare wires together is part of the manufacturing process; however, you have to untwist, after spot welding the end, so you don't have a short. The cables were not coiled like the picture. They were hard fan-folded. I don't have a datasheet for this wire; however, most cables have a minimum bending radius that you should not exceed for various reasons. And, since the fiberglass sheathing seems to fit loosely around the conductors I have a little concerned about conductor migration in a cable with sharp bends. However, I have not seen any problems. For hobbyist use, this works fine. The price was right for this hobbyist's budget. I would have concerns if using it in a business application.

When compared to the one that came with my test equipment these measure very close to same temp I was getting from the original one.