Hewlett Packard 5301A Counter Plug-on Module

Cleaning up and pho­tograph­ing a Hewlett Packard 5301A 10 MHz counter plug-on mod­ule for the 5300 series mod­u­lar mea­sur­ing system.

Hewlett Packard 5301A counter plug-on mod­ule front panel

The HP 5301A counter mod­ule is com­pat­i­ble with both the 5300A and 5300B mea­sure­ment sys­tems. It can han­dle fre­quen­cies up to 10 Mhz and can dis­play 6 dig­its on the 5300A dis­play mod­ule and 7 dig­its on the 5300B dis­play module.

HP 5301A Counter back panel

It is a basic no frills counter with an exter­nal gate input, auto gate selec­tion, three man­u­al gate ranges, sen­si­tiv­i­ty adjust­ment, wave­form selec­tion, and check function.

HP 5301A cir­cuit board bot­tom view

Compared to the oth­er 5300 mea­sure­ment sys­tem plug-on mod­ules, the cir­cuit board is sparse­ly pop­u­lat­ed. There are 6 IC’s, and 9 tran­sis­tors on the board, along with some oth­er high qual­i­ty pas­sive components.

HP 5301A cir­cuit board top view with plug-on connector

Most com­po­nents on the board are dat­ed from 1970, so that sets this mod­ule at just over 51 years old in ear­ly 2022. For it’s age the mod­ule works well, and just need­ed a gen­er­al cleanup and some DeoxIT D5 on the front pan­el switch con­tacts to restore it to full functionality.

HP 5301A cir­cuit board and back of front pan­el view

Unfortunately all of the front pan­el knobs are miss­ing their cen­ter inserts and are cracked, but still func­tion as need­ed.
I haven’t been able to source an online man­u­al and schemat­ic for this mod­ule yet, but will include it or a link if one becomes available.

One Reply to “Hewlett Packard 5301A Counter Plug-on Module”

  1. Hi, I liked your site for the HP5301A. I recent­ly found an old bench unit from my murky past, I am 82 and been retired a long time now. I noticed that you did­nt have a Manual. I did­nt either. A FREE abre­vi­at­ed ho-hum pho­to copy is avail­able at (davmar.org) ‑https://www.google.com/url?sa=t&source=web&rct=j&opi=89978449&url=https://www.davmar.org/Spec/HP5301A.pdf&ved=2ahUKEwiCkcamz9SIAxVR7skDHblMHyw4FBAWegQIFxAB&usg=AOvVaw2pzVCcemIIACMmqEfkVtce . I am sure they will oblige you.
    Have a great day Cliff Hall (Canada)

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