New Centre Post Test Day
A break in the WX gave me time to do the first bit of testing for the new air coaxial aluminium centre-post. I first had to lower my mast and remove my original Hexbeam and remove the original centre-post. Few cups of coffee and I was ready to tackle it.
The post is inserted into the original hub for the first time, new flanges are slightly higher and will hide the extra height of the GRP insulator
Original wire elements are attached to the air coax centre-post.
Coax attaches directly to the coax centre-post, no need to split the coax any more. I may change this to a N-Type socket in the near future. Note the two eyelets, these perform two functions. The first is to hold the top cap in place and the second is to attach the optional ice support cords to them.
A few alterations had to be made to the positions of the cleats that hold the wire elements in place but all in all it was quite an easy task and only took a few hours to compleate.
SWR test, charts show SWR on band edges, first red line = 1.5
Test equipment Mini VNA
20 Meters
17 Meters
15 Meters
12 Meters
10 Meters
6 Meters
Conclusion
Each element is slightly to short, I can only assume that this is due to the hardware sizes being smaller, EG the nuts and bolts that hold the wire elements on the original centre-post are M6 x 25mm and have two large 10mm nuts on each one. This adds to the length of each element. The new coaxial post only uses M4 machine screws and small 6mm nuts.
When I return from Ramsey Island EU-124 on the 20th of July I will be cutting some new elements to fine tune the SWR on each band. Very pleased with the results so far.
