Or simply fuse externally with a reasonable fuse holder and fuse. Over the years I have seen fuse fail due to simple age. Nothing more.
On Fri, Jan 15, 2010 at 9:36 PM, Tom Holmes, N8ZM <thol...@woh.rr.com>wrote: > HI Rick... > > That helps a lot. It also tells me the real reason why the fuse is open > ;-(. > > > Thanks! > > Regards, > > Tom Holmes, N8ZM > Tipp City, OH > EM79xx > > -----Original Message----- > From: Rick Karlquist [mailto:rich...@karlquist.com] > Sent: Friday, January 15, 2010 8:48 PM > To: thol...@woh.rr.com; Discussion of precise time and frequency > measurement > Subject: Re: [time-nuts] HP10811 losing EFC > > Tom Holmes, N8ZM wrote: > > While on the subject of 10811's, I have one which appears to have a blown > > fuse. Bypassing same, it seems to work OK, so suspect that tiny filament > > or > > whatever simply succumbed to some shock or vibration, or maybe just old > > age. > > I don't recall the current draw now, but it seemed reasonable at the > time, > > and it came up on frequency and appeared to be controlling the oven temp > > OK. > > > > > > Would like to replace the fuse with something more correct than a #22 > > before > > I let it go online full time. > > > > Any ideas for where to get replacement, or a suitable substitute? > > > > Thanks. This is a fun list to monitor. I learn more in a day here than > > anything else I've ever done. > > > > Regards, > > > > Tom Holmes, N8ZM > > Tipp City, OH > > EM79xx > > The fuse in an interesting topic. It is a thermal fuse, not an electrical > one. It deals with oven failure. It does not prevent the oven from > failing, but rather limits the amount of damage and smoke if the > oven runs away. The main purpose is to limit toxic outgassing, > rather than to protect the oscillator, although it may > accidentally do that. I have never heard of a case > of an oven running away, although it is theoretically possible, > for example, if the thermistor is open or disconnected. > (I have never heard of a thermistor failing either for that matter.) > The fuse cannot be soldered in for the obvious reason that it > cannot tolerate solder temperatures. It is instead inserted into > a non gold plated socket. In 99+% of "fuse failures", the fuse > has not blown (as can be confirmed with an ohmmeter) but instead > is not making contact. You might see if your fuse is still good. > In any event, I recommend bypassing the fuse with a jumper and > not worrying about it. There is far more chance of the fuse > "failing" than the oven running away. > > Rick Karlquist N6RK > > > > > _______________________________________________ > time-nuts mailing list -- time-nuts@febo.com > To unsubscribe, go to > https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts > and follow the instructions there. > _______________________________________________ time-nuts mailing list -- time-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there.