Ben Jackson wrote:
I would like to pre-calculate an approximate match to Z=50ohms which
I can put directly at the feed point and shrink-wrap with the balun.
Is there a way to do that, or is it too touchy to do without measuring
the actual antenna?

If you were within 20%, you would be lucky. Best to fine
tune it before shrink-wrapping it.
--
73, Cecil http://www.qsl.net/w5dxp