[Elecraft] KX1 on AAAs or Lithium Polymer?

[Fred Jensen]

One Ham's Experience:  Good News:  The LiPoly I got (local RC hobby 
shop) was just great!  I did not deplete it on our cruise thru the 
Panama Canal, maybe 6 hours operating time (mostly listening and no 
CQ's), but I did rag chew a bit with a number of SA stns.  Ran a Spartan 
Sprint after return without recharging just to see if I could.  Voltage 
stayed nearly constant until full discharge, at which point it dropped 
quickly.  As quickly, I recharged it on a MAHA 77.

Bad News:  It worked again very well in the next Spartan.  Then I got 
busy, and didn't check it for perhaps 5 months.  At N6A (Alpine County, 
CQP), I tried it our before the contest, and it was toast.  They are 
extremely light (a factor in Spartan, but I wonder in a back pack), they 
seem good, but they are expensive, and I've heard they die in a year or 
so, regardless of how you use them.

WAYNE:  To your basic questions -- I wouldn't spend much (or any) time 
adapting the KX1 to LiPo.  Mine came with tinned leads on which I put a 
coax plug.  The expense is a real downer.  The difference in power 
between 6 and 8 AA NiMH's seems minimal.  Yes, Alkaline dry cells do 
have a non-flat discharge curve, but you can get an bunch of them at 
Costco or Sam's and they're what I generally use.  I think the weight of 
the additional batteries is overshadowed by the weight of the solar 
panel and regulator for those who really do back-pack (I did but I don't 
anymore -- too old).

I know you have to keep up with technology and the ever-increasing 
demand for "one more feature," but I would caution against messing 
around with a success, which my KX1 is right now.  Besides, we're 
"amateurs," and you have to leave us something to mess around with!

73,

Fred K6DGW
Auburn CA CM98lw


wayne burdick wrote:
> We've located a 4-AAA cell battery holder that would fit inside the KX1 
> (one at each end of the bottom cover, as with the present AA holders). 8 
> cells would provide 10 or 12 volts, giving you significantly more power 
> output than 6 of the same cells (as much as 4 watts). The tradeoff would 
> be in battery life. AAA-size NiMH, alkaline and lithium cells provide 
> around 1000 to 1250 mA-hours, or around half as much as similar 
> high-capacity AA cells.
> 
> Another option would be to use a small lithium polymer battery. 11 volts 
> at up to 1450 mA-hours or so might be possible, although these batteries 
> are very expensive. AAAs might be preferable in a pinch because you can 
> buy them anywhere. In the field, you can borrow triple-As from 
> flashlights or other portable electronic devices. The difference in 
> weight between 8 triple As and a LiPo battery is probably only couple of 
> ounces, so weight is not likely to be the primary criteria.
> 
> You'd probably get five to eight hours of casual operation with NiMH, 
> LiPo, or lithium cells, which are preferable to alkalines because of 
> their flat discharge curve. Of course you could recharge NiMH or LiPo 
> cells in the field with a small solar panel. (Has anyone tried using 8 
> AAA cells with the KX1?)
> 
> We could (in theory) create a new bottom cover option for the KX1 that 
> would include two 4-cell AAA holders or a LiPo battery, plus a charge 
> controller that would run from the KX1's DC input jack. The battery 
> holders and charge controller components could be soldered to a thin PCB 
> module that runs the full length of the bottom cover. In the case of 
> AAAs, we'd include a switch to select rechargeable or non-rechargeable 
> batteries. You might be able to recharge while operating, although this 
> would have to be tested, since some charge controller generate 
> significant noise.
> 
> Any input on such a product would be appreciated. If there were 
> significant interest, we'd try to have it ready early next year.
> 
> 73,
> Wayne
> N6KR