Andre' Kesteloot, N4ICK has recently advised me of the web address for the 3C85 
Data
Sheet (Philips Components).  Many members of this reflector will know that this 
is
becoming a very popular material for use in LF equipment, following its use by 
David
Bowman G0MRF in his 250 W PA.

(I have used 3C85 ring cores in David's PA; LF SWR bridges; antenna matching
transformers; and in the grid and anode circuits of my valve PA with great 
success.)

For others who may be interested, the web address for the Data Sheet (PDF  file
viewer, such as Acrobat Reader, required) is:
http://www.acm.components.philips.com/pdf/3c85.pdf

Details of a UK source for 3C85 ring cores can be found at:
http://www.cableol.net/alg/radio/136/comps.htm

[Andre': Thank you for successfully navigating the Philips web site!]

Regards to all,
Steve GW4ALG