I use a propane torch for silver brazing. There are a few times when I
use more than one of those hand held torches with the small attached
tank, but usually using some insulating firebrick will confine the heat
enough.

For copper try using what is referred to as Sil-phos. It is a copper
alloy with some silver and phosphorus. I have the best results with
the 15% silver. No flux is needed.
It makes a strong joint and comes close to matching the copper in
color.

You might google for info on a hi-heat torch. It is a propane
compressed air and is suppose to be really good. I have not personally
seen one. Runs about 40 to 50 USD.

I am currently contemplating building the smallest propane torch
described in
"Gas Burners for forges, furnaces and Kilns ' by M. Porter. Check
Amazon for a longer description of the book. The torch might be
exactly what you are looking for.
Probably big enough for Jim to recommend for two or three cubic inches
of material.


Dan