Thursday, 18 April 2013

Show Antenna Designs

The paint for the Larkspur mast arrived yesterday. Theres still plenty of work to be done on it, but now I can get one with more than one task at a time!

The Doncaster Show will also need an antenna that will give us access to the WARC bands. Ive decided on a vertical system for this. I was intending to make something that would work on the fishing pole mast, but have decided instead on a Fan Vertical design that will utilise the 5.4m Clansman mast, there are several good reasons for this -

1. The 5.4m mast is much sturdier and will withstand the wind loading of the extra antenna wires better
2. It is already designed to be used as a vertical and has suitable fixings for the 20m element to run up the mast
3. I have spare mast sections that can be used to form a sturdy horizontal cross member support for the other four bands antenna elements
4. It will also be capable of supporting a VHF lightweight antenna at the top
5. Its guying radius is 3m, add on a 2m safety zone, and you have 5m. The required ground radials are to be 5m 30cm. A bit extra safety margin and its all contained.

My worry is being able to fit the 40m inverted V dipole into the antenna field, and having sufficient coax available if the shack has to be a distance from the antennas.

Ive also taken a punt, for a few quid, on a little digital voice recorder unit. The reason for this, is i'd like to do more CQ calls while mobile, but find it a bit tedious! If this sounds decent, and I can suitably modify it to feed into the mic audio and PTT system of the FT-857D, then it should just be a touch of a button to put out a CQ. I know its just a promotional toy, but it is from Cisco, so with any luck its half decent audio.

No comments: