[tig] New PEC's

[Dave Corbitt]

At 09:08 PM 12/1/2004, lunarfilms wrote:

>I am thinking of replacing the PEC's in my turbo I was assuming that the 
>hamamatsu part numbers which are in there are the ones I want to replace 
>them with, is there any better suggestions for replacements?
>
>The Hamamatsu part numbers are
>
>R2154  (2)
>R3356 (1)
>
>I think the way my machine is setup the Green and Red are the same and the 
>Blue is different,
>
>Fairly standard?
>
>-Rob-


That's not the way they usually are. I think you have the model numbers 
mixed up. The usual numbers are R3256-02 in the Red and Green sensors, and 
R2154-02 in the Blue. In my work on those machines in years past, I never 
found an advantage to using the R2154-02 in the Blue channel. In fact, the 
2154 is spec'd as a scintillation counter PMT and has a fixed gain first 
dynode. There is no signal to noise advantage to this in a telecine, just 
higher gain. These PMTs can overload on high lights because of that fixed 
gain first dynode so be careful. The better choice is to use the R3256-02 
type in all three channels, you eliminate the risk of blue channel overload 
when you use a brighter CRT or more efficient lens which can occur with an 
R2154-02 in the Blue channel. The -02 suffix indicates an HA  coating 
(anti-reflection) to increase efficiency slightly.

Good luck

Dave Corbitt
Post Logic NY
http://www.postlogic.com/