Cushcraft A3 back in Action
By, Peter KA1AXY

The beam down at the shack is finally back in working order.   Thanks to Bob, W1RH, and his antenna analyzer, we have a set of curves that prove we have restored the beam to its original specs (SWR below 2:1 over 500 KHz on all 3 bands). Although, it does look like 20m could use a bit of tweaking.

The first photo shows a trap being tested, and the second photo shows the phase versus frequency plot. 

It wasn't all easy, though. We suspected that the 15 meter traps had been "scrambled", but didn't know quite how to prove it.  Dave, K1HT, came to our rescue with a posting which explained how to identify the two varieties of traps, using a network analyzer.  Network analyzers are very expensive pieces of test equipment, but, fortunately, I have one at work.  All of us who work in the lab are hams, so when I wanted to hook the traps up and test them, I had to fight off the helpers!

The resonance point is the frequency where the phase goes through zero (where the sloped line intersects the dotted line).  When you position the cursor at this point, you can read the frequency (and the phase value) at the top of the display.  Director 15-meter traps resonate about 150 KHz higher than reflector and driven element traps.  All traps on both club A3s have been identified and marked.