Test Equipment Buying FAQ: Keithley Multimeters, Sensors, Thermometers, and Calipers

At our lab, I'm the one who manages test equipment and supply orders—roughly $150,000 a year across 20 vendors. I report to both operations and finance, so I'm the person stuck between "we need it yesterday" and "make sure it's compliant." This FAQ covers the questions I get asked most often about bench multimeters, temperature sensors, and calipers.

Is the Keithley 2000 or the Keithley 2015 THD Multimeter Better for Us?

Both are 6.5-digit multimeters. The big difference is the Keithley 2015 THD multimeter includes a built-in total harmonic distortion analyzer, which makes it useful for audio amplifier testing and low-level AC signal work. According to Keithley's product documentation (available through Tektronix), the 2015 is positioned as an audio-grade DMM. The Keithley 2000 multimeter is the classic general-purpose bench meter for DC and AC voltage, current, and resistance, and it's often enough for everyday lab work.

From a purchasing perspective, I would ask your engineers what they are actually going to measure. If the answer is "we build and repair audio gear," the 2015 is worth the extra cost. If you mostly need trustworthy DC measurements, the 2000 will do the job without paying for features that sit unused.

If you are wondering which one to request on a first order, I would start with the 2000 unless a project specifically calls for THD. In our case, the 2000 handles 95% of daily work. The 2015 is for the one project that measures distortion in power supplies. If no one can name a specific signal path that requires THD, a standard 6.5-digit meter is probably the right call.

Are Keithley Instruments Worth the Cost for a Small Lab?

It took me about four years and 150 purchase orders to understand that the cheapest quote is not always the lowest total cost. Back in 2021, I let a procurement manager talk me into trying a less expensive meter from another well-known brand. The unit came on time, but readings drifted during temperature cycling; the test results could not be trusted. We had to send it back, wait for a replacement, and rerun a whole validation batch. The savings disappeared quickly.

Here's the thing: the lowest quote is easy to calculate but hard to defend when it fails. Keithley is not the cheapest brand, but for precision measurements, the reliability and long service life make it a defensible buy. That doesn't mean you need a full suite of instruments from day one. I have placed orders for a single meter without any pushback. Small doesn't mean unimportant; it means the supplier needs to earn your larger orders later. When I was starting out, the vendors who treated a $300 order seriously are the ones I still use for $10,000 orders. (Yes, this is a pitch for treating every purchase like a long-term relationship.)

What Calibration Paperwork Should I Check Before Anything Ships?

Three things: calibration certificate, serial number matching that certificate, and a valid date. In that order. I didn't fully understand this until a shipment in 2023 arrived with a certificate for a different instrument. Our quality engineer caught it, but only after the package had been opened and logged in.

Ask whether the calibration is ISO/IEC 17025 accredited, because many high-precision buyers require that. Also ask if the certificate is NIST traceable. When I do the final check, I look for the uncertainty statement. If the certificate doesn't include it, I go back to the vendor before approving payment. A certificate with no lab name or no uncertainty statement is almost as bad as none. And keep a copy on file. This is one of those boring but expensive details that can save you in an audit.

Starrett vs Mitutoyo Calipers: Which Brand Should I Order?

This decision kept me up for a week. I went back and forth between Starrett and Mitutoyo calipers: Starrett has the American heritage, while Mitutoyo tends to be easier to get from our distributors and comes with more options for digital output. Ultimately, I chose based on the person who would actually use them — the machinist preferred the feel of one over the other. That mattered more than the brand name.

For everyday work, a caliper is a tool, not a trophy. Look for IP rating, battery life, data output, and whether the distributor can provide a NIST-traceable calibration certificate. If you buy from a reputable dealer, both brands are solid. The better question is what your local repair cycle looks like. Also, compare model to model, not logo to logo; the lower-priced caliper from either name can be very different from their higher-end models.

What Should I Know When Buying Temperature Sensors and a Thermometer for Fever Temperature Screening?

If you are buying a thermometer for fever temperature screening, don't treat it like an industrial process sensor. Clinical screening requires tighter accuracy—typically around ±0.2°C over the range of 35 to 42°C. Standards like ASTM E1965 cover infrared forehead thermometers. So check the spec sheet for the clinical accuracy, not just the "measure-to-100°C" claim.

For temperature sensors in general, the right answer depends on the temperature range and environment: thermocouples for wide ranges, RTDs for stability, thermistors for high sensitivity. What I mean is that buying a sensor without knowing the process is like buying a caliper without knowing what part you're measuring. (Ugh, we learned that by ordering a thermocouple that was too fragile for a motor housing.) Also, if a thermometer will be used near an air vent, place it in a stable environment; readings from a drafty spot will be harder to rely on.

How Do I Buy Keithley Gear as a Small Company Without Getting Ignored?

Look, some suppliers assume a one-unit inquiry is not worth their time. The good ones don't. I have had excellent luck using authorized distributors and simply asking for a formal quote with lead time, calibration, and warranty. If a vendor won't answer basic questions because you are buying one multimeter, that tells you how they will act when you have a problem later.

We have also ordered Keithley instruments through online distributors, sensors from specialized industrial suppliers, and calipers from a local cutting-tool dealer. Each order was relatively small—sometimes just two sensors or one meter. Good suppliers still processed the paperwork correctly, and those are the ones we trust with bigger purchases now. One vendor that answered a $400 quote the same day now gets our quarterly orders.

How Do You Compare Quotes for Keithley and Sensors Without Getting Stuck?

I use a simple spreadsheet: line-item price, shipping, expected calibration cost, lead time, warranty, and return policy. "Cheapest" on paper is not cheapest if the unit arrives without calibration paperwork and a second invoice for a certificate. What I mean is, price is the starting point, not the decision.

For a Keithley 2000 or a set of sensors, I ask for the total delivered price, not the base price. Then I verify supplier reputation by asking for a recent reference or checking their response time. Slow email replies usually mean slow support later. If a vendor won't put calibration on the quote, that's a red flag. It doesn't matter if it's a Keithley 2015 THD multimeter or a batch of thermocouple sensors.