Topband: Beverage question...

[StellarCAT]

I just put up a DXE dual beverage... the manual does not say
(unless I missed it) nor does the ON4UN Low Band book say if it
is important to have the end "boxes" at or near the ground. Not
specifically. It does mention sloping the end for example but it
does not say if the reflection xfmr (essentially the termination
end) needs to be at or near ground level. Or stated another way 
if this is a problem.
I currently have it with the feed box and the reflection box at 
the same height as
the wire - at about 5' height with a ground wire going down the
5' to the ground system (4 ground rods). Is this a problem?

Second I want to "isolate" my feed coax - anyone know the best
(read lowest cost) place to get the ferrites for doing this? I
will need 100 plus so a reasonable cost is hoped for. Also if
you know a part number or description.

thanks

Gary K9RX