Wilcox Engineering

Every now and then the issue of solder has been discussed (in great detail) on the Elecraft Reflector; there are also recommendations on the Elecraft site as well. Here's where I came out on the whole thing:

In early 2000, I started using the 0.031" Kester #24-7150-8800 '245' No-Clean 1.1% Flux (Sn62/Pb36/Ag02). The product description states that ... "the residues from the 245 [flux] are designed to be left on with no post-soldering cleaning." At one time early on, the silver solder was the Elecraft choice. It might be difficult if you need to do rework, but it worked fine for me for years and made a clean finished board.

Later, I went to the 0.025" Kester #24-6337-8809 '245' No-Clean 1.1% Flux (Sn63/Pb37). It makes a very nice solder connection, and it seems a little bit easier to work with. As to cleaning boards, I've had no need, nor request for that matter, to clean any of my boards after soldering them with this solder. I've used this solder now for several years and have had no problems with it at all.

My final favorite is the 0.015" Kester #24-6337-8806 '245' No-Clean 1.1% Flux (Sn63/Pb37). The smaller diameter makes it easier to control the quantity of solder on a connection. 

For toroid wires, I sometimes use the 0.025" Kester #24-6040-18 3.3% Flux (Sn60/Pb40). The "44" rosin is a more-active flux and makes for good wetting on difficult wire. 

I use a Hakko 936-12 soldering station, usually set to around 800-degrees F with a 1-mm tip or smaller. I run it near max 900 degrees for toroid wires to burn off any remaining enamel. For large areas, like the finals in the KPA100, I use either a larger tip or my old high-power Wall 214 LTN (like the current Wall LG-400C).