A Tale of Poor Engineering


Or, “One More Improvement to the Improved SWA !”


Jeff  , VE1ZAC


Yesterday was a blowout weather wise for a planned dive, so I spent the day in the shop and performed a complete rebuild of the control unit for the SWA. I admit the MK1 unit got pretty ratty. Embarrassing actually.  I might actually want to show this thing to other prospective low band aficionados, and that unit just wouldn’t cut the mustard. It worked fine, but my normally solid building methods deserted me towards the end. What convinced me to start over, however, was a paint failure ! I had sprayed the box with a gloss lacquer I had lying around, and it was just to shiny for my shack.  So, I ran up to my local hardware store ( yes, Canada Tire) and got a can of semi gloss Krylon. I normally am a big fan of fast dry Krylon, but I can’t recommend you spray this stuff over another gloss coat. Basically, after 5 days, the paint still seemed ‘soft” and even a little sticky. It didn’t set properly. That was the trigger for my construction dissatisfaction, and to the shop we went !


I had another slightly larger case and lots more copper clad circuit board. Normally I would have made one board with this technique, but the L&C switch assembly really seemed fine the way it was, so I re-used it. Everything else started over.

This is more of a picture story, so I will let the photographs tell the story. Needless to say, this was a big improvement.  The unit even performs better, probably due to a lack of pesky cross coupling and interaction. I added a preamp off-on switch as well.