[Amps] Tank Coil spacing

[Steve Flood]

As I begin to experiment with component layout on an amp ("playing chassis-chess"), the biggest hurdle is trying to maintain the requisite space around the pi and L coils.  I wound them 3" diameter 10 AWG.  My reading has informed me to keep the coils 'half the coil diameter' away from the RF compartment walls and tuning/loading capacitors.  This really eats up some space in the RF compartment!   When I look at photos of commercial amps or even other homebrew amps, I notice this spacing is not adhered to.  I could save sapce by using just a pi tank, but again my reading indicates that the pi-L is better engineering pracitce.  So now my questions...

1.   How critical is this spacing guideline?  How close can you actually place the coils before Q is affected or other bad things happen?  How do the commercial amps get away with it?

2.  It seems most of the homebrew and Handbook amps I see are Pi tanks.  Is the Pi-L really necessary?


Thanks, 
Steve KK7UV