NO! You can't use any soft solder! Only hard solder or silver brazing alloy. There are so many misnomers in th' biz' and it's getting worse by the hour.
Silver soldering to the welder is silver brazing or hard soldering. Temps are well over 1000 degrees F the work pieces glow cherry red!
Soft soldering is usually carried out with the classic tin/lead alloys, and this is radio/electronic soldering with rosin cores for fluxing. Now that all the babies and safety nerds are crying in their beer about lead in solder, most twenty first century solders are made of pure tin with a tiny amount of silver in it and so Radio Shock and others are calling it silver solder. This is not good for grids!
You will still have to get an oxy-acetylene setup, ideally, but some prestolite acetylene setups will work for small pieces.
The absolute best way is to spot weld.
Richard Hull
Created on Friday, February 16, 2001 5:14 PM EDT by Richard Hull