<<<< However, I cannot find a supplier who sells
drone comb foundation anymore.  I tried Dadant, Kelley, A.I.Root, and Mann
Lake and struck out.  Anybody have any suggestions for finding drone
foundation in the U.S?>>>>
 
You don't need it.  Let the bees make their own.  If your brood combs are 
in good shape, all worker cells and no patches of drone, you can
concentrate all the drone brood on to one comb.  I split a brood comb
horizontally in two with a quarter inch strip of wood.  The bottom half is
fitted with worker foundation and the top half is given a half inch starter
strip fixed to the top bar.  Invariably the bees will turn the top half
into drone comb and fill with eggs.  When capped this section is cut out, 
leaving the starter strip for next time, and checked for mites.  The comb 
goes to the bird table and is quickly cleaned out.  I normally use two such
combs for each hive, putting them in at intervals to get continuous
production.  Drone production here is from April to mid July so if your
season is the same you have left it too late for this year.  
If you raise your own queens and select fathers as well as mothers this is
a good way to fill a hive with drones.  You can still check for the
presence of mites by doing a one in ten sampling instead of destroying the
comb.                   Sid P.