doorknob caps

I have a question about doorknob caps. I am still very new to tesla
coils and I am trying to learn as much as possible before I try to put
one together. My question is, would some 1200 pf/5KV doorknob caps be ok
to use on a small to medium sized coil? I am using a 15KV/30mA NST. Any
help would be appreciated. Forgive me if this is a question best left
for another list like the Tesla-2 mailing list, but I cannot seem to get
on that mailing list.