With switches, I was worried about lead length since the one side is only 0.5pF and that represents almost 12kohm at 27MHz, and that's only 69nH in the inductance realm, so I thought any excess wire, even if short with respect to 69nH would throw off the balance.
I did, however, finally realize that PCB traces, when above a ground plane (transmission line), do not have the 24nH per inch that a free wire has, its more like 4-5nH, so maybe DIP switches would be ok since it is close to the ground below. That 0.5pF has me thinking that even the slightest change in parasitics will throw this thing off, but if they were individual switches, maybe that would work better.
Last nights thought was to throw some pin headers on the board between each cap and sensing resistor, and another to break the current pickup wire between them, and then use some of those little jumpers that are often seen on old HDD slave select pins. Bought a kit last night with finger grips molded into them. But now after reading your DIP switch suggestion, I was able to find single dip switches on amazon so I will try those first and see what happens. It would be a lot easier than fumbling with those tiny jumpers. Thanks!
edit: I just hope the open switch capacitance is nowhere near 0.5pF...
edit2: and I now realize that I will not be doing this with a 10x probe either. Crap.
