Let's see,
pc, tw, thr, fr, fv, sx, svn, ght, nn, tn, jck, qn, kng.
Doesn't work if you drop all the vowels.
unka, dunka, trunka, qunka, cunka, sunka, siunka, ounka, nunka, dunka, junka, queunka, kiunka.
Doesn't work in Davidian either.
Strange...
David