The phonograms CH and TCH both represent /ch/ or /ʧ/ using the International Phonetic Alphabet. Logic of English Spelling Rule 27 tells us when to use TCH for spelling:
TCH is used only after a single vowel which says its short or broad sound.
Spelling Rule 27 does not address words where CH is used after a single short or broad vowel. Interestingly, there are only a few words where CH is used after a single vowel which says its short or broad sound:
However, there are many words spelled with a TCH after a single short or broad sound. These are fantastic words to add to your Spelling Journal: