[Elecraft] K2 backlighting brightness

[AA5CK]

Hi Ron

I went through this a few weeks ago. After trying several different 
value resistors in parallel with R 10 I ended up with a 39 ohm one. This 
dropped the the total resistance to about 18 ohms and increased the 
current from the original 24 mA to 34 mA. Still not as bright as #5523 
but close. Further increase in current didn't seem to increase the 
brightness much so I went with the 39 ohm resister but YMMV.

I don't know about LEDs dimming but an increase in current may shorten 
their life. Hopefully 5 mA per pair won't have a significant effect. 
Maybe we'll get a more definitive answer from  the list.

This is really not a big problem and I am certain I would have never 
noticed the difference in brightness had the two rigs not been setting 
side by side and even then it took several days before I noticed it.

Good Luck....Ted...aa5ck


ron_w wrote:
>  
> Both K2's go remarkably the same, but the older K2 has a noticeably 
> dimmer display than the new one which raises the questions :-
> (1) Do the back light LED's dim with time?  ......the older K2 *has* 
> had a lot of use.
> (2) Would changing R10 to (say) 22ohms have any detrimental effect  on 
> the life of the back light LCD's?
>  .
> Cheers.......Ron ZL1TW