I have discovered the secret to eternal bulb life in the 238. You
can't beat eternal.
http://lists.contesting.com/archives//html/TenTec/2003-12/msg00217.html
73,
Barry N1EU
On Thu, Feb 14, 2008 at 1:10 AM, Jim Brown K9YC
<k9yc@audiosystemsgroup.com> wrote:
> I do several things to make these bulbs last longer and get more
> brightness from lower current (long life) bulbs. First, I put white
> tape on the inner black panel below the dial and around the bulbs
> (all the black paint that isn't visible through the glass) to better
> reflect the light up to the tuning dial. That improves brightness.
> Second, I use 756 bulbs, which draw only 80 mA at 14V and are rated
> 15K hours. (The "standard" 1815 bulb draws about 300 mA and is rated
> only 3K hours.) Third, to further improve life, I run them at
> slightly lower voltage by adding one or two forward-biased 1A diodes
> in series with the DC feed from the RCA connector.
>
> If you don't have 756 bulbs, you can still add multiple diodes in
> series with the standard 1815 bulbs. That will also reduce brightness
> a bit, and improve life quite a bit.
>
> FWIW -- I've tried multiple LED's in each opening with series R to
> limit current in one 229 tuner. LED's last OK, but I have not been
> happy with the result visually.
>
> 73,
>
> Jim K9YC
>
>
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