Recently, I hauled an old handheld down off the shelf and discovered,
not surprisingly, that the battery pack was deader than the proverbial doornail. I like my old HT even though it does only
one band (2 meters). I had one just like it back in my Civil Air Patrol days so I decided to see if I could build an external
battery pack to power it. (Kind of like the old Quantum Ham Pack, now long gone, that I used for the HT in the old days.
A little persuasion separated the back of the pack from the rest of the enclosure
and I found 10 cells about 2/3 the size of an AA cell welded together to provide 12 volts to the HT. Of course they no longer
were capable of doing that. The cost of having a local battery store rebuild the pack was not unreasonable, but they did not
have the cells in stock and it would take several weeks to get them in.
I decided, as I mentioned before, to try my hand at building an external pack and converting the stock pack to include
a power connection after removing the cells that it contained.
In my radio room I have several file cabinets that contain a whole lot of various
parts, enclosures and other devices that I keep around just because I might need them someday. With a little searching, I
came up with a suitable enclosure, two 8-cell battery holders and a coil cord with two conductors. A quick trip to my
local Radio Shack and I had the male and female coaxial power connectors.
I started the project by removing the stock cell stack from the batery pack of the
HT. The stack was held in with a little double sided tape, so slight prying with a small screwdriver got them out easily.
A suitably sized hole was drilled in the side of the battery pack for the female power connector and it was installed. I then
soldered wires from the connector to the two contacts on the cover of the pack that make contact with the rest of the HT.
A little adhesive to keep the cover in place and the repurposed battery pack was installed back on the HT.
The external pack started with an ABS project enclosure that measured about 6" x 3" x
2". I got mine from Radio Shack some time ago just to have it on hand, but they are available from many sources. As it turned
out, that was the perfect size to fit the two 8-cell battery holders side by side. With AA cells in place in both holders
and the two holders wired in parallel, I get a nominal 12 to 13 volts from the combination. You may ask why I chose to use
non-rechargable AA batteries instead of ni-cads. My thought process was that in a time of emergency one may have difficulty
finding 110 Volt AC to run the charger but any retailer of any size will have more AA batteries in stock. A hole was
drilled in the side of the enclosure for the coil cord and a salvaged belt clip from some unknown project or device from
long ago was bolted to the outside of the cover of the enclosure.
The coil cord was soldered to the wires from the battery holders after first passing the
end of the cord to the inside of the enclosure. At the other end of the cord, the matching male coaxial power connector was
soldeered on and the joint covered with heat shrink tubing. This did require a little pre-planning to get several short lengths
of heat shrink over the correct wires and cables in the correct order.
To keep the battery holders from rattling around in the enclosure, a piece of scrap
rigid packing foam was carved to be a snug fit inside the enclosure and the cover with the belt clip was then screwed
into place with the four screws provided.
The coil cord was plugged into the female connector on the side of the HT and testing
commenced. Because the HT had been idle for so long, the memories were all gone, but the HT powered up on the first try.
A brief test transmission on 146.52 showed that the radio was putting out a full 5 watts and further testing showed that all
of the functions of the radio were A-OK. I then programmed the radio with a few of our local repeater frequencies,
offsets and tones. I was able to hit all of them without difficulty.
With the external power pack on my belt where it weighs no more than other HT's I
have used, the HT it powers can now be kept in a shirt pocket or clipped to my ARES vest. Since there are no batteries in
the HT itself, it is much lighter and easier to handle. In use, I just lean my head slightly toward the HT and push the PTT
button without actually having to unclip it from my clothes.
If you have an old HT whose battery pack has gone west, you may want to try building an
external pack for it and bring it back to life.