News

Jan 27, 2014
Category: General
Posted by: m0cke

I've finally done it, M0CKE/m again !!

CMS - 1.11.1 - Baltra
 

HF Monoband Beams Project

The first of the new mono-band HF beams was installed for CQWW 2013 today (20/10/2013).

The design is my own using MMANA and spending many hours playing with lengths and spacing’s I finally opted for a 5 element design on a 10m boom, not wide spaced by any means but I was looking for consistent F/B ratio with good 50R impedance with direct coax feed and reasonable forward gain across the whole of 20m.

The antenna will be used in various contests from CW through RTTY to Phone and once we get the second tower installed will become a permanent fixture.

The design took many weeks with MMANA, then the antenna was drawn up in a CAD package along with components required to complete the build, then I ordered all the raw materials from 3 suppliers and submitted the component drawings to a water jet engineering company for the components to be cut.

After another 3 weeks all the components were ready and it was time to start manufacturing the antenna, we first made jigs for drilling all the telescopic elements, and element mounting plate clamps, drilled everything and dry assembled the antenna over 3 days.

Happy with the mechanical structure we assembled everything with conductive grease and installed on the tower and raised to 30ft.

Initial tests were carried out showing 1.0:1 VSWR across the band and some huge 5/9 +50DB signals coming from Europe, a quick F/B check was made showing around 25db which is similar to the modelled ratio.

Time to put a call out, 4pm in the afternoon I wasn't expecting much but after working a few Europeans we were called by West Malaysia, then Vietnam and Afghanistan, all giving good solid reports.

Needless to say I was satisfied with the first test and next weekend will see me trying to claim 1st place in CQWW 20m single band for the 3rd year running, hopefully I can improve my placing in Europe and Rest of World also.

Look forward to hearing you on the air.

Jim M0CKE

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