Re: Ageing components


Kevin Oconnor
 

Another insidious failure mode is aging of rotary wafer switches. Older HP & Tek gear used these a lot. I had a spectrum analyzer once, HP modular I think, where span switching was erratic or non-functional. After disassembling the mechanical gearing junk behind the panel to get to the wafers, I found that the wipers were attached to the plastic wafers by melting a post projecting thru the Beryllium copper wipers. The plastic was embrittled and the posts were shearing off. Some of the wipers were lost within the instrument. A basket case I concluded. I ended up scraping the plugin and eventually the mainframe when I found most all plugins had the same problem.

kjo

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