Topband: Preamp power supply

[N1BUG]

Fellow Topbanders,

I've run into a glitch!  The local switchers have found a 
new way to harass me!    :-)

I am looking for suggestions on *aggressive* power supply 
decoupling / filtering for my W7IUV preamp.  The preamp 
works great when powered from a battery but is totally 
useless on the power supply I built for it.  Experiments 
thus far have not led to an acceptable solution.

The preamp is the latest revision W7IUV circuit from Larry's 
web site, using a 2N5109.  It is very well shielded.  The 
power supply consists of transformer, full wave bridge, 
LM317T regulator plus output filtering (the filtering is 
what I am now experimenting with).  Incidentally, I used a 
Corcom EMI filtered power entry module for the AC line to 
the power supply.

By all available evidence, the preamp is being killed by 
noise from local switching power supplies (and/or other 
crap!) entering via its power source.  Again, all is well 
if I power the preamp from a battery.

Thanks & 73,
Paul  N1BUG