B&K's 375 is part of the 'Dynamic' VTVM line that succeeded the earlier all-tube 177 / 277. It provides the ~10 MΩ DC input impedance that tube-circuit work demands (grid-bias, AVC, screen-supply nodes that a 20 kΩ/V VOM would crush), with the classic taut-band analog meter movement and the 1.5 V / 5 V / 15 V / 50 V / 150 V / 500 V / 1500 V range cascade. Ohms function uses an internal 1.5 V battery and reads from ~0.1 Ω to ~1 GΩ on a logarithmic scale.
VTVMs (Vacuum Tube VoltMeters — even the late solid-state ones kept the name) are the standard high-Z voltmeter for tube-era service work. The 375 is the workhorse counterpart to the [Simpson 311-2 VTVM](../Simpson%20Model%20311-2%20VTVM/CLAUDE.md). Where the Simpson 260 VOM (20 kΩ/V) is loadable, the 375's 10 MΩ input keeps grid and screen-supply measurements honest. This unit also has an RF probe input for measuring up to 250 MHz — useful for IF alignment in tube-era radio receivers.
A multi-volume deep dive on this instrument is in planning. When the first volume lands in the source project's 02-inputs/volume_sources/, this page upgrades automatically — no website code change required.