Lee your K3 is protected from over current in a number of ways. The worst case I can imagine in your shack is a heavy metal object falling across and shorting the unprotected power leads to the K3. I have had this happen. To protect against this you place fuses at the battery. Your Astron has foldover current limiting so it is also self-protecting but if it is connected directly to the battery you will need a second set of fuses at the battery to protect the charging circuit from reverse feeding a shorted cable. I think the Astron primary is already fuse protected.
You have already indicated you have grounded everything in your shack. If that includes the negative of your battery then there is no need to fuse the negative since you have provided a shunt path around the negative fuse. A word about fuses and fuse holders. Buy the best quality available and that usually means buy American. Fuse holders are probably the least reliable component in your system. Fuse are the second least reliable. Use only spade type fuses (that's called a faston connector). Protect the assembly from heat and moisture. Clean up any corrosion with a baking soda paste and a toothbrush. Remember a bad fuse is one that doesn't fuse at its rated current. A good fuse is one that fuses at its rated current. No wonder there is so much confusion about fuses. 73, Fred, AE6QL -----Original Message----- From: [email protected] [mailto:[email protected]] On Behalf Of Lee Buller Sent: Tuesday, June 26, 2012 1:57 PM To: Elecraft Reflector Subject: [Elecraft] Fusing the K3 Power Line Reading the manual....it says that two 25 amp fuses should be in both the positive and negative leads going to the K3 from the battery. Now, what about AC supply like and Astron 35M. Should you also have the same thing - two fuses inline from the PS to the K3. The manual talks about a "battery" but doesn't address that specifically (or you could infer) for a AC power supply. Or, am I just loosing my mind? Lee In our day and age it seems that Common Sense is in short supply. If you don't have any Common Sense - get some Common Sense and use it. If you can't find any Common Sense, ask for help from somebody who has some Common Sense. Is Common Sense divine? Common Sense is the image of the Creator expressing revealed truth in my mind. - John W. (Kansas) Never interfere with anything that isn't bothering you. ______________________________________________________________ Elecraft mailing list Home: http://mailman.qth.net/mailman/listinfo/elecraft Help: http://mailman.qth.net/mmfaq.htm Post: mailto:[email protected] This list hosted by: http://www.qsl.net Please help support this email list: http://www.qsl.net/donate.html ______________________________________________________________ Elecraft mailing list Home: http://mailman.qth.net/mailman/listinfo/elecraft Help: http://mailman.qth.net/mmfaq.htm Post: mailto:[email protected] This list hosted by: http://www.qsl.net Please help support this email list: http://www.qsl.net/donate.html
