Hi can you tell me what type of meter i would use,such as a small millivolt or a small milliamp etc? and what kind of phone jack can i substitute,I can not find one like it?? also for everyone's information I found a great company in Nebraska that sells all types of hard to get parts..I got all parts for my metal detector except the coil and case.It is Surplus Sales of Nebraska.www.surplussales.com if interested thanks for info Lloyd