I think you're correct. Well observed!
Is this some personal rule of yours that consonants can't be preceded by the indefinite article an? You should patent it!
I'm just guessing, and I don't remember any specific rule, but I believe one says "an" when the next word begins with a soft consonant, like "honor", rather than a hard consonant like "ham". It's just an auditory distinction between words that might otherwise sound a little funny when spoken, i.e. uh onor.
In addition, when acronyms are used, you go by the sound of the first letter, so it would be "an HDTV" versus "a BRD"...the letter H when pronounced starts with what we would recognize as a vowel sound, like "aitch", so you use "an"