Bias cell

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Bias cell

Post by Motorola man on Sat Mar 02, 2013 10:50 pm

While working on my Howard 418, I came across a part that I was not familiar with. It looked kind of like a metal acorn. I found it on the schematic, but it wasn't clearly labeled as to what it was. After some digging through a few other schematics, I found the mystery part again and it was labeled as a bias cell. I did a quick search and found a full description of the part, as well as a few rejuvenation / replacement ideas. It's basically a one volt battery used to bias the tubes. Of course after 75 years, it was dead. With nothing to loose, I opted to try the rejuvenation technique. I drilled a small hole through the carbon top, injected some distilled water and sealed the hole with some silicone. To my surprise, it worked! It now reads 1.2 volts, so back into the radio it went. Hopefully it will live on for many years to come. If not, I'll simply be replacing it with a watch battery.
Dave
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Re: Bias cell

Post by Dr. Radio on Sat Mar 02, 2013 11:14 pm

Wow, now that's something I think is safe to say it won't be that easy to rejuv a cell phone battery in 50-75 years! Razz
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Re: Bias cell

Post by chrisc on Tue Mar 19, 2013 1:45 pm

That's amazing - who would have thought it ?

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Re: Bias cell

Post by Bill Cahill on Tue Mar 19, 2013 2:50 pm

Thanks for the tip. I've also used low microfarad low voltage electrolytics to make it work. But, I am amazed that it can be brought back to life.
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Re: Bias cell

Post by sprman on Tue Mar 19, 2013 7:49 pm

Ahh they built it good back then huh? Sprman

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Bias cell used in G.E. 250 and 260

Post by dan88king on Fri Oct 18, 2013 4:39 pm

I have run into the use of a bias cell in the G.E. 250 and 260 portables that can run on a 2 volt storage battery, using a vibrator power supply. Their chassis also has that strange shaped component, like a round fat disk with a little dome on one side and two wire leads. I didn't know they could be reactivated. Your idea of using a watch battery sounds good, and they don't leak and corrode.

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