[BC] recommended fluxes for silver soldering ground system/radials?

[Timothy West]

title says it all - I am going to install a new safety + rf ground  
system prior to installation of my RA 250.  I have 30 ft of solid  
wire silver solder, 4 8-ft copper-clad rods and (so far) about 24 ft  
of tinned 1" copper strap in 6 ft chunks. also planning on some hefty  
solid wire.

What's the best flux on the market to use to bond this stuff  
together? I dont want my joints looking like that 'ground' connection  
Barry published the other week. Have Weller 275 watt gun, propane  
torch, but I dont know a thing about what flux I need for a good  
flowed joint using solid silver wire solder that will hold up to  
outdoors. I'll also be using this for a future radial system on 160  
meters.

Tim