The Mojotone Bias Checker Kit by Hoffman Amps is the best of both worlds when it comes to ease of assembly and cost effectiveness. This kit is easy to build, and comes with assembly instructions in the link below.
Kit builds one bias probe to be used with a multimeter
Materials list for each Bias Current Checker:- 1 - 8 pin tube base with hole and sticker
- 1 - 8 pin PC board tube socket
- 1 - Dual banana plug
- 1 - Bias checker PCB
- 1 - Bias checker Ring
- 1 foot of 18 gauge zip cord
- 2 feet of buss wire
ASSEMBLY INSTRUCTIONS