Re: [Elecraft] K3: Power cable question
--- David Cutter <[EMAIL PROTECTED]> wrote: > Glad you raised that point, Brian. In my Sunday > school classes I ask the > question: "what does the fuse protect?" It's a > revelation to all when I > give the right answer. > > On our 240V distribution system, a melted cable can > lead to a severe shock > hazard and I'm guessing that in the 110V > centre-tapped system since the > shock hazard is so much less, the next major hazard > is fire, so, I've often > You are right David. 110 VAC is much safer than 240V, it can just barely kill you. Cookie, K5EWJ Willis 'Cookie' Cooke K5EWJ ___ Elecraft mailing list Post to: Elecraft@mailman.qth.net 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
Re: [Elecraft] K3: Power cable question
Glad you raised that point, Brian. In my Sunday school classes I ask the question: "what does the fuse protect?" It's a revelation to all when I give the right answer. On our 240V distribution system, a melted cable can lead to a severe shock hazard and I'm guessing that in the 110V centre-tapped system since the shock hazard is so much less, the next major hazard is fire, so, I've often thought that we are protecting against 2 hazards, each with a different emphasis in each case. In a 14V dc distribution system there is no real shock hazard (SELV), so the remaining hazard has to be fire, so, a slow fuse is not a problem, since heating effect in the wiring is so much slower. Anyone care to comment/add? David On Jun 16, 2008, at 9:59 PM, <[EMAIL PROTECTED]> <[EMAIL PROTECTED] > wrote: 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... Most people don't know that the purpose of a fuse or circuit breaker is to protect the power distribution wiring, not the electronic component itself. Wire will carry a surge without too much temperature rise. The idea is that the fuse will blow or the breaker open before there is any chance of damage to the wire. This means that a fuse or breaker cannot protect your active devices. If you want that level of protection you need something like a power supply with fold-back current limiting. Brian Lloyd ___ Elecraft mailing list Post to: Elecraft@mailman.qth.net 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
Re: [Elecraft] K3: Power cable question
On Jun 16, 2008, at 9:59 PM, <[EMAIL PROTECTED]> <[EMAIL PROTECTED] > wrote: 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... Most people don't know that the purpose of a fuse or circuit breaker is to protect the power distribution wiring, not the electronic component itself. Wire will carry a surge without too much temperature rise. The idea is that the fuse will blow or the breaker open before there is any chance of damage to the wire. This means that a fuse or breaker cannot protect your active devices. If you want that level of protection you need something like a power supply with fold-back current limiting. Brian Lloyd Granite Bay Montessori School 9330 Sierra College Bl brian AT gbmontessori DOT com Roseville, CA 95661 +1.916.367.2131 (voice)+1.791.912.8170 (fax) PGP key ID: 12095C52A32A1B6C PGP key fingerprint: 3B1D BA11 4913 3254 B6E0 CC09 1209 5C52 A32A 1B6C ___ Elecraft mailing list Post to: Elecraft@mailman.qth.net 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
[Elecraft] K3: Power cable question
Hi Ron, Thanks for the analysis. You pointed out several things I was unaware of related to these types of fuses. Nice to learn something new! I'm in the process of redoing the power distribution in my shack, so will take this info into account. Fortunately, it's been a while since I've blown any fuse. Cheers, Julius Julius Fazekas N2WN Tennessee Contest Group TnQP http://www.tnqp.org/ Elecraft K2/100 #3311 Elecraft K2/100 #4455 Elecraft K3/100 #366 ___ Elecraft mailing list Post to: Elecraft@mailman.qth.net 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
Re: RE: [Elecraft] K3: Power cable question
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'" > 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: Elecraft@mailman.qth.net > 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: Elecraft@mailman.qth.net 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
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: Elecraft@mailman.qth.net 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
[Elecraft] K3: Power cable question
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 Julius Fazekas N2WN Tennessee Contest Group TnQP http://www.tnqp.org/ Elecraft K2/100 #3311 Elecraft K2/100 #4455 Elecraft K3/100 #366 ___ Elecraft mailing list Post to: Elecraft@mailman.qth.net 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
RE: [Elecraft] K3: Power cable question
Me too, but I realized that the K3 draws somewhat more current than the K2/100. Depending upon the band antenna, etc., the total current can exceed the rating of the rating of the 20-amp fuse in the K2/100 power cord. Ron AC7AC -Original Message- > ...whether the K2/100 power cable is interchangeable with the K3/100 > (i.e. do the Andersons have the same orientation on K2 and K3)? Yes, they have the same orientation. I initially ran my K3 with my K2/100 cable. 73, Lyle KK7P ___ Elecraft mailing list Post to: Elecraft@mailman.qth.net 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
Re: [Elecraft] K3: Power cable question
...whether the K2/100 power cable is interchangeable with the K3/100 (i.e. do the Andersons have the same orientation on K2 and K3)? Yes, they have the same orientation. I initially ran my K3 with my K2/100 cable. 73, Lyle KK7P ___ Elecraft mailing list Post to: Elecraft@mailman.qth.net 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
[Elecraft] K3: Power cable question
I haven't been able to locate this information in the documentation, so perhaps a kind soul could oblige? In anticipation of a K3/100 kit's arrival, I would like to know the length of power cord supplied and also whether the K2/100 power cable is interchangeable with the K3/100 (i.e. do the Andersons have the same orientation on K2 and K3)? Many thanks. DaveL G3TJP ___ Elecraft mailing list Post to: Elecraft@mailman.qth.net 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
