[TenTec] Better Bulb Life in TenTec 229, 238 Tuners

[Jim Brown K9YC]

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