A regular fuse should blow at 2.6 x the rating within 30s, in other words very slowly. It's only a short circuit that will normally blow a new fuse. Have not seen any data on old fuses which might get metal fatigue. There are faster fuses, but the fastest are rf transistors - on three legs anyway...
David G3UNA > > From: "Ron D'Eau Claire" <[EMAIL PROTECTED]> > Date: 2008/06/16 Mon PM 06:52:16 BST > To: "'Elecraft Discussion List'" <[email protected]> > Subject: RE: [Elecraft] K3: Power cable question > > Hi Julius: > > I measure just over 20 Amps under some bands and conditions running the K3 > at 100 watts. Like the K2, I suspect the current draw varies a bit depending > upon the rig, the actual parameters of some of the transistors, etc. That's > normal, according to the K3 specs, which rate the current demand at 17-22 > amps at 100 watts in transmit > > IMX fuses have a nasty habit of suddenly opening after being cycled a number > of times near their rated limit, even the 'slo-blo' type that are supposed > to offer a little resistance against sudden failure when their current limit > is reached will sometimes open unexpectedly. > > I've seen fuses operating near their current limits develop cracks so they > act like thermal switches, causing power to go off suddenly then, after a > few seconds (while the fuse cools) suddenly come back on, then switch off > again as soon as a higher current is drawn such as for transmitting. > Eventually they fail completely, but in the meantime the symptoms can be > pretty confusing. > > As a matter of practice I try to allow significant headroom between the > rating of any fuses and the actual current draw, and I always have spare > fuses on hand since they can and do fail over time, even if not subjected to > excessive current. > > Ron AC7AC > > > > -----Original Message----- > > Ron, > > I've been using my K2 cable with my K3, including > contests, without an issue. > > Considering what the KPA100 will do with my 160M > setup, in the way of drawing current, I think there is > enough wiggle room not to worry too much. > > The K3 barely gets warm when I run :o) > > 73, > Julius > > > _______________________________________________ > Elecraft mailing list > Post to: [email protected] > You must be a subscriber to post to the list. > Subscriber Info (Addr. Change, sub, unsub etc.): > http://mailman.qth.net/mailman/listinfo/elecraft > > Help: http://mailman.qth.net/subscribers.htm > Elecraft web page: http://www.elecraft.com > ----------------------------------------- Email sent from www.virginmedia.com/email Virus-checked using McAfee(R) Software and scanned for spam _______________________________________________ Elecraft mailing list Post to: [email protected] You must be a subscriber to post to the list. Subscriber Info (Addr. Change, sub, unsub etc.): http://mailman.qth.net/mailman/listinfo/elecraft Help: http://mailman.qth.net/subscribers.htm Elecraft web page: http://www.elecraft.com
