Hacking & Overhauling a VTVM (Heathkit IM-18 and similar)

I bought a used Heathkit model IM-18 Vacuum Tube Volt Meter (VTVM) on eBay and did repairs and calibrations necessary to bring it up to full operational status and "factory" specifications. Along the way, I got an alternate set of VTVM test leads, replaced some worn components, and 'hacked' the circuit so the Ohmmeter battery is no longer required. In the video, I cover all aspects of the project. I especially think that my hack of the simple battery eliminator, although not an original or unique circuit, will be helpful to others. I included not just the final design of this hack, but also the thoughts and experiments that led up to the final design.

• #howto_style
• #heathkit
• #im_18
• #vtvm
• #vacuum_tube_volt_meter
• #battery_eliminator
• #voltmeter_hack
• #vtvm_hack