HP1 HP2 The red framed element is on a PCB of a 1973 Hewlett Packard 5300A Measuring System, Digital Multimeter Board. The double wire seems to have normal resistance. What is the screw for?

  • \$\begingroup\$ Maybe a current shunt ? Or a fuse ? \$\endgroup\$
    – Mike
    Commented Mar 27, 2021 at 23:20
  • \$\begingroup\$ @Mike The analog part with shunts and voltage dividers is near the switches and test lead sockets. Anyway a shunt/fuse with 2 parallel wires seems unlikely. \$\endgroup\$
    – xeeka
    Commented Mar 28, 2021 at 0:37
  • \$\begingroup\$ it looks like an antenna \$\endgroup\$
    – jsotola
    Commented Mar 28, 2021 at 1:32
  • \$\begingroup\$ @xeeka: If it is the multimeter, then it is the HP5306A. The HP3000A is the base unit. The add ons make the function. The 5306 with the 5300 makes a multimeter. The site I linked to has schematics and photos. You might have to join the site to see the full versions. I couldn't get them on my phone, at any rate. \$\endgroup\$
    – JRE
    Commented Mar 28, 2021 at 2:02
  • \$\begingroup\$ @JRE Yes, I did download these documents last year. But this strange element is nowhere to be found. The PCB part containing that element is missing. \$\endgroup\$
    – xeeka
    Commented Mar 28, 2021 at 23:12

1 Answer 1


it appears to be having 4 connections if i'm not mistaken? if so it might be an inductive current sensor? I'm not entirely sure but that would be my best guess...

  • 1
    \$\begingroup\$ It has only 2 connections to the PCB. The 2 wires coming out of the white plastic ring just under the screw are touching each other midair and are soldered in one point to the PCB, as shown in the picture. \$\endgroup\$
    – xeeka
    Commented Jun 21, 2023 at 2:20

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