Fluke 789 Process Meter Review: Is This the Best Loop Calibrator?

I’ve been testing the Fluke 789 ProcessMeter lately, and it’s clear why this tool has earned such a strong reputation among technicians. This device combines a digital multimeter with loop calibration features in one handheld unit, making it much more convenient than carrying separate tools.

What impressed me most was the accuracy of the current measurement and sourcing capabilities. The 24-volt loop supply eliminates the need for a separate power source during offline transmitter testing. The built-in Hart resistor is another nice touch that saves space in my tool bag.

The dual display with adjustable backlight brightness works well in various lighting conditions. I found the quick span check feature useful, allowing me to toggle between 4 and 20 mA with dedicated buttons.

Battery life is decent for measurement tasks, though it drains faster when sourcing current. The external battery compartment makes replacements quick and easy. At just over a pound, it’s not too heavy for daily use.

The main downside is the price point, which puts it out of range for casual users. The interface can also feel overwhelming initially if you’re not familiar with process calibration tools.

Bottom Line

The Fluke 789 ProcessMeter delivers reliable performance for instrumentation technicians who need accurate loop calibration capabilities.

Its combination of DMM and calibrator functions in one tool justifies the investment for professional use.

Table of Contents

Overview Of The Fluke 789 ProcessMeter

After using this meter for several weeks, I found it combines two essential tools into one device. The 789 works as both a standard multimeter and a loop calibrator, which saves space in my toolbox.

Key Capabilities:

Measures and sources 4-20 mA signals with high accuracy
Built-in 24V loop supply for offline transmitter testing
Standard DMM functions for voltage and resistance

The dual display shows clear readings, and I appreciate the two backlight brightness settings. Battery life impressed me – around 50 hours for basic measuring and 12 hours when sourcing current.

What makes this tool stand out is the built-in 250-ohm HART resistor. I no longer need to carry a separate resistor for HART communication testing.

The rugged build feels solid in my hands, though it weighs about 1.3 pounds. Some users mention the selector switch feels less crisp than other Fluke meters. You’ll also need a Torx driver to change the batteries, which is slightly inconvenient.

For process technicians, this meter eliminates the need for multiple separate tools.

Key Features

After testing this meter for several weeks, I found it packed with useful features that make process work much easier. The 789 combines multiple tools into one device, which saves space in my toolkit and reduces the need to carry separate instruments.

Integrated Digital Multimeter and Loop Calibrator

The dual functionality impressed me right away. I can measure standard electrical values like voltage and resistance, then switch to loop calibration mode without grabbing a different tool. The meter handles 4-20 mA signals well, letting me both measure and source current loops.

The measurement accuracy stayed consistent during my tests. I appreciated having 1000V overload protection on most functions, though the mA inputs are limited to 150V protection with a 440 mA fuse backup.

24V Loop Power Supply

This feature saved me countless trips back to the control room. The built-in 24V supply powers two-wire transmitters directly from the meter. I tested it with pressure and temperature transmitters, and it provided stable power throughout my work.

Battery life varies based on usage. I got about 50 hours when just taking measurements, but only 12 hours when sourcing 12 mA continuously. The meter runs on a 9-volt alkaline battery, which is easy to find and replace.

Built-In 250-Ohm HART Resistor

The selectable HART resistor makes HART communication testing simple. I can switch it in or out as needed without external resistors or adapters. This feature alone eliminates extra components from my bag.

When working with HART devices, the resistor performed exactly as expected. It integrates seamlessly with the meter’s other functions, so I can measure loop current and enable HART communication at the same time.

Dual Display With Enhanced Backlight

The large dual display shows two readings simultaneously. I found this helpful when comparing input and output values or monitoring multiple parameters. The screens are easy to read even in bright sunlight.

The enhanced backlight has two brightness settings. The dimmer setting works well in normal conditions and saves battery life. The brighter setting helps in dark spaces like control cabinets or equipment rooms.

One minor issue I noticed is that the selector switch feels somewhat soft compared to other Fluke meters. It still works fine, but lacks the crisp click I expect. Also, you’ll need a Torx driver to change the battery, which might be inconvenient in the field.

The auto-step and auto-ramp functions work smoothly for testing control loops. The 0% and 100% buttons quickly jump between 4 and 20 mA, making span checks fast and easy.

Pros and Cons

After spending time with this process meter in the field, I can see why it’s become such a popular tool for technicians and engineers working with control systems.

Pros

The 789 really shines when it comes to versatility. I found myself carrying just one device instead of multiple separate tools. It handles standard electrical measurements while also working with 4-20 mA signals.

The dual display makes my work much faster. I can see multiple readings at once without switching between functions. The backlight has two brightness settings that work well in different lighting conditions.

Key strengths I noticed:

Built-in 24V loop supply eliminates need for external power
0% and 100% buttons let me quickly jump between 4 and 20 mA for span checks
Manual and auto step functions make calibration tasks smoother
Rugged construction holds up well in industrial environments

The battery life impressed me too. I get around 50 hours of normal use from one 9V battery.

Cons

The selector switch feels mushy compared to other Fluke meters I’ve used. It doesn’t have that crisp, confident click I expect from this brand.

Battery access requires a Torx driver, which is annoying when I need to change it in the field. Most meters use standard screws or no tools at all.

The price point puts it out of reach for casual users. This is definitely a professional-grade investment.

Main drawbacks:

Selector switch lacks tactile feedback
Torx screws for battery compartment
Higher cost than basic multimeters
Learning curve for all the process functions

The display, while functional, could be larger given the meter’s size. When working in bright sunlight, I sometimes struggle to read the numbers clearly even with the backlight on.

Customer Reviews

After checking what other users said about the Fluke 789, I found some clear patterns in their feedback. Most buyers work in automation and controls, and they love having one device that does multiple jobs.

What People Like:

Reliability – Multiple reviewers trust the Fluke brand name
All-in-one design – Replaces several separate tools for 4-20mA work
Build quality – Users call it durable and rugged
Display – Easy to read in field conditions

Common Complaints:

Selector switch – Some users find it feels “squishy” compared to other Fluke models
Battery access – Requires a Torx driver to change batteries
Price – Several mention it costs more than basic meters

The 4.6-star rating from 91 reviews shows most buyers are happy with their purchase. Field technicians especially appreciate carrying one meter instead of multiple devices for process control work.

User Experience In The Field

After testing this 789 for several weeks on different job sites, I found it handled most automation tasks without needing extra tools. The 4-20mA simulation feature worked well for troubleshooting loop systems quickly. I could test transmitters and check valve responses in one go.

The display stayed easy to read even in bright sunlight. The meter felt solid in my hands and survived a few drops on concrete floors. Battery life lasted through long work days without issues.

What worked well:

All-in-one design reduced tool bag weight
Quick loop diagnostics saved time
Rugged build handled rough field conditions

What could improve:

Selector switch feels mushy compared to other Fluke meters
Need special Torx driver for battery changes
Price point is high for occasional users

The 789 proved most useful for daily process control work. Technicians doing frequent 4-20mA testing will appreciate having everything in one device.

Battery Life and Portability

After weeks of testing, I found the power situation quite practical for fieldwork. The meter runs on four standard AA batteries that came in the box. I didn’t need to hunt down special battery types at the hardware store.

Battery performance exceeded my expectations. During my testing, the batteries lasted through several long work days without dying. The meter doesn’t drain power quickly when measuring signals.

The size and weight work well for portable use. At just over one pound, I could carry it in my tool bag without strain. The dimensions make it easy to hold with one hand while working.

Portability gets high marks. The compact design fits in tight spaces where I needed to take measurements. I took it to different job sites without issues.

One small downside is battery replacement. You need to carry spare AAs for longer projects. The meter will drain faster when using the built-in loop supply feature.

Conclusion

After spending time with the 789, I can say it lives up to Fluke’s reputation for quality. This meter eliminates the need to carry multiple tools when working with control systems. The ability to measure, source, and simulate 4-20 mA signals in one device makes troubleshooting much faster.

What works well:

Reliable performance you expect from Fluke
Clear, easy-to-read display
Durable construction for field work
Built-in loop supply saves time

Areas for improvement:

Higher price point than basic meters
Selector switch feels less precise than other Fluke models
Requires Torx driver for battery access

The 789 is best suited for professionals who regularly work with process control systems. While it costs more upfront, it replaces several separate tools. The investment makes sense if you need its specific capabilities regularly.