I have used the Battery Tender as well, the smaller one for the K2 and a larger one for external batteries.
You can't use the existing K2 power jack to charge unless you remove some components, as because of the voltage drop, the smart charger will be outwitted and overcharge the battery. So, at least some modification is necessary, and if you leave the resistor in place, your K2 will be consistent with others and can properly handle the 14v slow charge through its DC jack. I believe drilling the hole is the best solution, because it adds a second jack explicitly for charging. I saw Wayne N6KR's K2 and he had mounted an extra plug or two in the back of his K2 as well (though his was for DC out), through one of the old transverter holes. So I think it's A-OK, kinda like replacing the RCA phono jack that Heathkit used to use for antenna connections with an SO-239. Here's how I did it: http://wa5znu.org/log/2005/01/k2-charging-jack.html Since I did it, Unibits have come down in price, and inexpensive competitors from Harbor Freight and Northern Tool are available. I found that I had to stop just shy of the battery to get the hole the right size. Originally I planned to replace the K2 power switch with a double-pole double-throw switch to allow me to have the charging jack active or the battery connected, but not both; however, I eventually decided not to do this and just hook the charging jack up through an internal fuse as Don recommended. I used a mini-blade fuse internally in the plus line, and ran a separate minus line. I do notice some hum if the charger is on red; this could mean my battery is getting old, or it could happen to everyone (although Don hasn't reported it is an issue for him). Having the charger jack also means you can use a Northern Tool 350ma folding solar panel and replenish the battery in the K2 while it's operating! I don't have the Radio Shack part number for the jack I used, but you can see it in the 4th picture. I believe they have a couple of sizes; it's up to you whether you want to use the same as the K2 power plug, or use a different size to more clearly separate them. Leigh/WA5ZNU On Fri, 26 Sep 2008 14:17:28 -0400, Bob <[EMAIL PROTECTED]> wrote: > Hi Bruce, > > I do not have the battery pack in my K2 however for years > I have been using these chargers for various > Gel cells and small lead acid batteries: > > http://batterytender.com/selection_guide.php > > The Plus model at $60 is a 4 step charger for gel cells, > and others, and the JR at $40 is a 3 step charger > that I have used also on very small Gel cell batteries when a lower > charge rate was desired. > > These are very popular in the Motorcycle world. They > are discounted quite a bit and I've seen them > for $35 and $27 each. When the MC's are retired for the winter I just > leave a charger connected and they are > ready to go in the spring. I have 3 Plus models and a JR and they have > never failed me. > > No financial interest just a satisfied customer. > > 73, > Bob > K2TK > > > Bruce James Howes wrote: > >> Hello all, >> >> Is there a simple off the shelf model of battery charger which I can >> buy or build that will properly charge the K2 battery? >> I'd prefer not to drill a hole in the rear apron, so I'm looking for >> a commercial solution, ideally with an adjustable output. >> >> What have you found that works, or how did you solve your K2 battery >> dilemma? >> >> Thanks! >> >> >> 73 Bruce W1UJR >> www.w1ujr.net >> > _______________________________________________ > 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 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
