Power to the Peanut Whistle

Grab your batteries! It’s on! (With apologies to Southwest Airlines.)

Earlier this year, I finished off an Elecraft KX-1 (40 meters and 20 meters). I bunged up the tiny crimp connectors on the wires that carried juice from the internal batteries to the radio. So I took the courageous route: I decided to leave the batteries out of the KX-1′s little black box (at least for now).

But I also didn’t want to haul around a small 7 amp-hour battery for long outings. A brief consultation with Dr. Google led me to engineer Alan Wilcox’s website and a neat little external battery pack he put together for a Small Wonders Lab “Rockmite” transceiver.

[Aside: One of the neat things about ham radio is the largely open-source-like pool of ideas hams are willing to share with each other. End aside.]

After studying his approach and tweaking for additional batteries, here’s what my power pack looks like:

Just about everything came out of my junk box except the battery holders — enough for two sets of eight AA batteries, the two sets connected in parallel en route to the radio — and the plastic box. The box is the smallest of the “Really Useful Box” collection at Staples. I’ve also seen some at WalMart, although not the same variety of size. And purple isn’t my color either.

Anyway, the stacked battery holders fit fairly snuggly into the box in two of their three dimensions. But that leaves some room for sliding.

So that space instantly became the storage space for the cable connecting the battery pack with the KX-1.

The good news: With that cable stuffed in there, the batteries have no place to slide.

In an email exchange with Alan in anticipation of building this, he indicated an interest in seeing how long a dual eight-pack would last. The 1.5-volt lithium batteries I picked out are rated at 2.8 amp-hours, according to the folks at Elecraft (and the package!). So that yields roughly 5.6 amp-hours with the two 12-volt collections wired in parallel.

Figure duty cycles and all that, and one could envision getting perhaps 12 hours of operation out of a battery pack like this. We’ll keep you posted (if I remember to log the op time!)