The GW Instek GDM-397 is a 4000-count handheld digital multimeter from the GDM-300/400 Series, designed as a compact, battery-operated instrument for service engineers working away from the bench. The series is positioned around mobile-oriented features: automatic power-off to preserve battery life, a backlight display, a rotary selector with push-button operation, and temperature measurement for outdoor use. Within the series, the GDM-397 sits as the auto-ranging model with RS-232C connectivity and an analog bar graph.

The GDM-397 is built around the core measurement set required for field service and general electronics troubleshooting: DC and AC voltage to 1000 V and 750 V respectively, DC and AC current to 10 A through a fuse-protected input, resistance to 40 MΩ, capacitance to 4000 µF, and frequency to 10 MHz. Continuity testing with an audible beeper, diode testing, data hold, and relative mode round out the functions an engineer expects when diagnosing circuits in place. The 41-segment analog bar graph adds trend visualization to the digital reading, which is useful when watching a value drift or settle.

ValueTronics has been supplying test and measurement instruments since 1992, and every unit we ship — new or pre-owned — moves through our 20,000 sq ft secure warehouse at 1675 Cambridge Drive in Elgin, Illinois. The same facility handles inbound inspection, functional verification, and outbound fulfillment, which is the operational difference between a verified instrument purchase and an unverified marketplace listing. When you buy a GDM-397 from ValueTronics, the instrument has been handled by people whose job is to know what it is supposed to do.

Brand Heritage

GW Instek is the international brand of Good Will Instrument Co., Ltd., a Taiwanese test and measurement manufacturer founded in 1975. The company has operated continuously under the same corporate identity and has not been acquired or rebranded.

Compare Other Models in This Series

The GDM-300/400 Series is a family of seven handheld digital multimeters from GW Instek, sharing a common design philosophy oriented around portable service work: rotary range selector, push-button operation, 9 V battery power, fuse-protected 10 A current input, and continuity testing with an audible beeper. The family spans entry-level 3 ½ digit instruments through 22000-count true-RMS models with RS-232C connectivity, allowing a single product line to cover hobbyist, field service, and bench-adjacent measurement needs.

Models within the series differ primarily on display count, ranging behavior (auto vs. manual), true-RMS support, interface options, and the presence of specialized functions such as hFE transistor testing, EF detection, temperature measurement, and analog bar graph display. The physical enclosures fall into three sizes, with the higher-count and RS-232C-equipped models sharing a common 87 × 180 × 47 mm chassis.

Each new GDM-300/400 Series model listed below has its own dedicated product page with condition-matched pricing and availability. Specifications are presented for comparison so that the model best suited to the application can be identified before purchase.

Within the family, the GDM-397 is positioned as an auto-ranging 4000-count meter with the RS-232C interface, analog bar graph, MAX/MIN capture, and auto power-off, but without true-RMS AC measurement, hFE testing, EF detection, or temperature measurement. It is the choice when auto-ranging convenience and PC connectivity matter more than true-RMS accuracy on distorted AC waveforms.

The most consequential differences across the GDM-300/400 family are display count, true-RMS support, and interface. The GDM-461 leads on display count (22000), true-RMS, RS-232C, and analog bar; the GDM-452 offers 4 ½ digit manual ranging with AC current true-RMS but no interface; the GDM-360 combines 6000 counts with true-RMS and RS-232C; the GDM-397 and GDM-398 are 4000-count auto-ranging meters with the GDM-398 trading the RS-232C interface for hFE and EF functions; the GDM-357 and GDM-350B are entry-level 3 ½ digit instruments.

The comparison table that follows shows display count, ranging behavior, true-RMS support, voltage and current ranges, resistance and capacitance ranges, frequency range, and the presence of diode, continuity, temperature, hFE, RS-232C, and analog bar features across all seven models. Selection within the family should be driven by the highest-frequency measurement requirement (true-RMS for non-sinusoidal AC, RS-232C for logging, hFE or temperature for specific service work).

Additional differences in specifications beyond the few shown above are not listed here — see each model's full specifications below.

Accessories Supplied

• User manual x 1
• Test leads
• Battery

Product Core & Specifications

Please review the Manufacturer's Data Sheet to verify published specifications. Feedback on this webpage is always welcome — please reach out to your Test Architect at any time for questions or concerns. Thank you, we truly appreciate you being our customer.