On 40m at last… (Part I)

Using a Buddipole antenna (BP) for my SOTA activations leaves me high and dry when it comes to the 40 m band. I was never able to build an efficient BP for these frequencies and received many ‘complaints’ that I never activate on 40m, thereby leaving out the ‘local’ chasers. This is going to change now…

RG174 based double Bazzoka

RG174 based double Bazooka

Yesterday I received a package from my buddy and SOTA Mountain Goat Herbert/OE9HRV, containing a home brew double Bazooka for 7 MHz based on RG174 coax. Herbert is my go-to guy when it comes to antennas. On our joint SOTA activations in OE he always carries an  impressive assortment of home brew antennas to the summits, and due to this weight I  would NOT want to carry his backpack – seriously. To see some examples of his creations, check out his FLICKR stream and/or QRZ page.

I had not known about double Bazookas before being educated by Herbert. It’s an efficient and quiet single band antenna based on 50 ohm coax cable, with the shield split at the center and feed line attache to it.  It can be used in a flat top or inverted vee configuration – the latter more suitable for SOTA. To save on weight, Herbert made it out of RG174 with a BNC connector, and used a wire-winder to create a small and easy to manage package. The final antenna is around 310 g (~ 11 ounces) and about 25 cm x 8 cm (~ 9.5″ x 3″ ).

Here are some pictures taken during the building process (click onto the picture for a larger version and slideshow):

Building process: Slide-1

Building process: Slide-1

 

Building process: Slide-2

Building process: Slide-2

 

 

 

 

 

Building process: Slide-3

Building process: Slide-3

 

 

 

 

 

 

 

 

 

 

 

Building process = Slide-4

Building process = Slide-4

The final product

The final product

Tuning the antenna: Feedpoint at 3m (9ft)

Tuning the antenna: Feed-point at 3m (9ft)

Tuning the antenna: Feedpoint at 6m (18 ft)

Tuning the antenna: Feedpoint at 6m (18 ft)

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

Can’t wait to try it out and see how it performs in action. The fresh snow (~45 cm or 1.5 ft) over the last three days cut me off from most SOTA summits right now. Stay tuned…


ATTENTION !! WARNING !! There are old mountaineers, and bold mountaineers... there are no old-bold mountaineers. Hiking and mountain climbing are potentially hazardous activities particularly in Colorado with its extreme elevations. I am not accepting responsibility for any death or injury resulting from activations based on my trip reports. Proper training, experience, and personal capability assessment is required - enjoy!


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On 40m at last… (Part I) — 1 Comment

  1. Pingback: สายอากาศ Double Bazooka « Kunawut's knowledge blog

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