Jul 6, 2008

HB0-summer 2008 preparation; 50MHz 7el PA3FGA design

Design 50MHz long-yagi by PA3FGA

From 7th july onwards PC5A, PA3FGA and PA5MW will be QRV from HB0 (www.sareis.li).
We have decided to use 2 different 50Mhz yagi's in order to maximize our performance; one 5el/5mtr boomlength DK7ZB design and a 7el/9mtr boomlength PA3FGA design.

Rens PA3FGA designed this long yagi, starting from a basic 7el/28Ohm DK7ZB version. He optimized the pattern, using a boom length of max 9mtr for reasons of transportation restrictions (max.3 mtr). The F/R specs have been optimized at only minor gain loss. See radiation plot.

Building the antenna

During these last 3 weeks Rens has been busy building this 'portable' 7el/9mtr(30 ft) boomlength long yagi. The whole package should be easy transportable on a car roof. However; Rens is not the kind of guy to produce just any 'temporary light- weight easy-to-go' construction. This meant balancing the various criteria, stretching all mechanical possibilities.

The single elements are mounted with help of customized 'perspex' plates which clamp on the boom.

Matching to the '28 Ohm' radiator is done via a 2x 1/4 wave 75 Ohm coax in parallel, according original DK7ZB design. Boxes are type IP66 and 100% waterproof.

The completed 30ft/9m antenna just fits in the backyard garden:

This is us, positioning the 28/50Ohm transformer section on the boom (PA3FGA, PA5MW).

Any practise results yet?
That is a defenitely no. We have no time left and just count on our luck ( and perhaps Murphy?).
There are still other things left to do before our departure tomorrow.

Meanwhile, while packing my stuff I managed to work from my shack:

6m today:

earlier this week:

1 comment:

Mark, PA5MW said...

OK, of course the element mounting plates were not made from perspex, but TRESPA.