Amateur Radio Station K6JEB

from beyond the horizon

My A3S or A4S

Posted by Jack on August 8th, 2010

So a few years ago I bought what I thought was a Cushcraft A3S Tri-band Yagi, used, on Eham.net classifieds. When I received it, I recall trying to set it up but being mystified since the traps were marked quite differently and the boom diameter was thicker.

Well I finally got around to figuring-out what I have, and here’s my best guess:

The whole thing is definitely a Cushcraft, but it’s an A3S driven-element and director, and the traps for and A3S reflector but the tip sections are longer and seem to be from the A4S. The boom is, as I said, from an A4S. The separate 10m element from the A4S is not present.

In essence, an A3S which can do more spacing.

When I bought this originally I was planning to take it out as just a two-element antenna for portable operations. But now I’m tempted to use this for contest season 2010.

Next step is to put it up on the crank-up tower and test-out gain and front-to-back. First, it seems I should try and get the director and especially the reflector (since it is a bit longer than an A3S reflector) resonant on their particular frequencies.

SO I’m thinking of using the driven-element center piece for the reflector and driven element to test their resonant frequency. I have a vague memory of these being 5% below the driven element for the reflector and 5% above the driven element for the director.