[time-nuts] Quieting the HP-113AR Clock/Frequency Divider

Jeremy Nichols jn6wfo at gmail.com
Sat Mar 17 22:38:45 EDT 2018


Those of us with the 1960-vintage HP-113AR/BR Clock/Frequency Divider know how noisy they are. The mechanical clock movement of my 113AR is loud enough that I really don't want to be in the same room with it. I don't know if the clocks are noisy from brand-new or if the mechanism gets noisier as the various parts wear with age.

Here's how I quieted mine:
• Wrap the outer cabinet of the 113AR in stick-on automotive sound deadener.
• Put the 113AR in a fully enclosed 4U rack cabinet.
• Stuff insulation into the cabinet so the 113AR is completely surrounded except for the front panel.

Should anyone be interested, I can provide detailed notes, a shopping list, and pictures. Total cost was about US$150 and would have been a lot less if I could have found a used cabinet at the surplus store. 

Jeremy



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