Hello Ethan
https://www.light-sources.com/wp-con...ead_info_0.pdf
If you are to print BW photopaper then cold cathode light requires a calibration procedure:
http://www.jbhphoto.com/wp-content/u...ljbharlin1.pdf
Because of spectral nature of the cold cathode light Ilford contrast filters will have a shift, see "Cold cathode enlarger heads" section in page 3:
https://www.ilfordphoto.com/wp/wp-co...Multigrade.pdf
Me, what I'd do is directly replacing the tubes by a "Do It Your Self" LED illumination, probably it would take less effort, you won't need antique spares in the future and also you won't need a calibration procedure if you take the right LEDs.
If you use warm white leds of about 3000K color temperature of (say +90) high CRI (color reproduction index) you will have a "standard" illumination that will work fine with Ilford Contrast Fiiters and papers.
I the past tungsten light was provocating a lot of heat and a cold cathode had a thermal advantage at the cost of having a non standard spectrum, today with LEDs you have both the Tungsten bulbs spectrum and no reheating.
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Instead using warm white LEDs, you may also substitute the tubes by RGB LEDs, using a separated power control for each channel, with that you would have a variable contrast head with no need for filters, you may do split grade printing by making two consecutive exposures, one with Green light and another one with Blue light, by adjusting power/time for each exposure you have different grades, this also allows to burn highlights with lower contrast and shadows wit a higher one. In both the green and the blue exposure you also throw red to see better (for burning/dodging), red it's not seen by the paper, so you expose with yellow (green+red) and purple (blue+red) like with Ilford contrast filters.
But using RGB LEDs may require a calibration work, while using warm white LEDs of high CRI is straighter.
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So my personal recommendation is that you consider investing in the effort to retrofit the illumination with LEDs rather than fixing the cold cathode gear.
Regards
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