VTTC tuned primaries?

[paul@abelian.demon.co.uk (by way of Terry Fritz <twftesla@uswest.net>)]

I notice in a couple of recent posts about valve driven CW
coils, a tendency to resonate the primary with an additional
capacitor. Why is this? It seems to me that a tuned
primary is a liability in this mode of operation. 
--
Paul Nicholson,
Manchester, UK.
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