[Milsurplus] A BA-1293 solution

[Hue Miller]

Tim, N6CC,  replied with this:

"Hi Hue - I rigged up a bias battery with 3 cells from a common 9 volt
"transistor radio" battery. 3 cells are held together in series with the
stainless steel ribbon straps and I just soldered to those and to the pins
on the BA-1293 base, positive grounded. A bit of heat shrink tubing
overall and it fits inside the original battery clamp. Works great, lasts
forever.
The radio will work without the battery but you can see the resulting
distortion on a scope and I can hear a little difference with/without as
well. That AF tube will be happier not drawing excessive plate current if
biased properly...If the original battery has 'gone fuzzy' there's no
telling what the grid voltage would be."

This is the same thing I was working on. Use AAAA batteries. Not so
common, but you can even find them in some stores now. Or, you can
rip apart industrial-grade 9 volt standard batteries and remove the 6
AAAA cells inside. These are linked with metal tabs. You can solder
to raw AAAA cells if you have to go and buy a pack. You take a bundle
of 3, they fit right in the original BA plastic, but more practical I think,
to just recover the plug base and use that only. Building up the diameter
of the AAAAs with a band of electrical tape makes the bundle fit more
snugly in the batt clamp. As long as you don't leave the taped assy there
til the tape becomes yucky and sticky, but that's a number of years.
I would think using new AAAA cells, the thing should last 5 years or so.
If you don't use the heat shrink as Tim did, I would put a small insulating
disk below this bundle of cells. In my case, the orig batt plug is damaged,
so I will have to take a couple pieces of stranded wire and solder right
to the batt socket and bring the wires up thru the pin holes.  The only
? remaining for me is which 9 volt battery brands are assembled this
way, with 6 AAAAs inside and not the usual original sandwhiched
layer stacked cells.
-Hue Miller