[Elecraft] Manhattan-style pad capacitance

[Jack Smith]

Geoff, GM4ESD, has asked the relevant question "how much shunt 
capacitance is present in a PCB island" when cut with a core drill?

I've tried to answer that question with a combination of theory and 
measured data, which are in close agreement. The details are at 
http://www.cliftonlaboratories.com/Prototyping.htm#Island_Pad_Prototyping. 
You can read the entire page, or jump to the capacitance discussion via 
the in-page link.

The short answer to the questions is "some" and whether "some" is too 
much depends on a variety of things discussed in the analysis. I will 
say, however, that the data has caused me to reconsider using the very 
thin 0.029" PCB stock for work at higher frequencies, as convenient as 
it may be for cutting and hole punching.

Jack K8ZOA