[time-nuts] HP 5370B low frequency modulation

Dr Bruce Griffiths bruce.griffiths at xtra.co.nz
Sun Jul 22 22:31:37 EDT 2007

Mike Feher wrote:
> ); SAEximRunCond expanded to false
> Errors-To: time-nuts-bounces+bruce.griffiths=xtra.co.nz+bruce.griffiths=xtra.co.nz at febo.com
> I believe it is almost impossible to have an intermittent thermal fuse due
> to their very clever design. Although over age they can open up. Once open,
> however I do not believe they can connect again. The fuse is simply to
> metallic contacts that are force to be in contact during assembly. Their
> normal desired resting state would be to be not connected. When closed, the
> fuse cavity is filled with wax, which mostly determines when the fuse opens
> (temperature). With too much current through the fuse, the wax heats
> allowing the contact to spring apart to their normal resting position. Now,
> with no more current flowing, the wax hardens almost immediately, never
> allowing the two contacts to meet again. - Mike 
> Mike B. Feher, N4FS
> 89 Arnold Blvd.
> Howell, NJ, 07731
> 732-886-5960

Whilst the fuse itself may not be the problem, it is a plugin component 
and the contacts may be problematic.


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