Kirk, thanks for the great explanation! I had understood that the article was describing the reference electrode and you needed a separate one for the salt but didn't quite understand the role of the Ag/AgCl inside the reference electrode. You have helped to clear this up.
Now the Ion-Specific Electrode (ISE) is the next part to investigate. Soldering silver wire to a piece of coax should be simple enough. What is the purpose of the glass? Sounds to me like it is to give a bit of stiffness and durability to the assembly plus protect the soldered connection and prevent it from contaminating the emulsion? I don't know anything about glass tubing but I suppose you can get it from a chemistry supplier or the big auction site.
I had found the other posts you mentioned and along with PE's book have started to fill in the shopping list for the two electrodes plus the salt bridge. This has all been very, very helpful.