Mammoth Uncensored Word List:
26 words ending with ph, 12 letters long

arithmograph cathodograph chemoautroph electrograph ellipsograph enantiomorph evaporograph flannelgraph harmonograph keraunograph laryngograph magnetograph marconigraph meteorograph multidigraph opisthograph ornithomorph oscillograph phraseograph pythonomorph rephotograph scattergraph spectrograph sphygmograph steganograph subparagraph