I have started construction of my new 11 meter 5/8 wave named the Super 58 Magnum…or S&M for short
… will have a 5/8 radiator and four ¼ wave horizontal ground radials, insulated from the mast and have a built in coax choke.
It is also going to be tested with the ¼ wave horizontal radial swapped out with steeply sloping 5/8 wave wire radials
The design I have come up with is down to the members of this forum
My thanks go to Marconi who recently model a 5/8 wave with 8 ¼ wave radials which show that they had very slightly less gain than just 4, hence its got 4
Marconi Perversely modelled a 5/8 wave for me with steeply raked radials a full 5/8 wave long and found the gain was promising but had very heavy CM currents on the mast and feed line
So hence my big insulator and built in choke
Also I thank W5LZ for some comments on chokes which made me decide 100% to have a choke
And Northern 35 for posting a link to G3TXQ choke charts
Progress so far
Looking at the Photos from the ground up you can see a length of 2 inch stainless pipe this will be the mounting point to clamp to my mast . in the pipe it has a fiberglass shaft bonded into it, This shaft started out as a 14lb fibreglass hammer shaft. Which I rapped with fiberglass matting and resin to increase the diameter to 47 or 48 mm to fit inside the stainless mounting tube and the radiator. Yes the radiator is going to be a huge 2 inch in diameter(hence the magnam moniker) tapering of to 1nch and a ½ (40mm) at the top…massive wind loading I know but the tubing is hi quality as it came from a portable scaffold system, although its thin walled at 1.6mm it is very springy when trying to bend it. The diameter, should help with bandwidth
Clamped to the fiberglass stub (hardly a stub its 3 feet long ) is the hub for the radials that I fabricated from stainless steel, the stubs are 16mm / 5/8 of an inch .I made it hefty as if I end up with the 5/8 wave 25 degree wire radials they may be used as guy ropes
The radiator as you can see is slid over the fiberglass stub to be clamped on, clamp not fitted as yet
The matching device is going to be the ring type, 1 end connected to the clamp that clamps the radiator on and the other end to the radial hub
Just below the hub around the fiberglass stub will be a piece of 4 inch plastic tube with the choke will be wound around , and the ISO socket mounted to the underside
Well that’s the progress so far .. I still need to find the stuff to make the ring, I will probably have to buy some 10mm solid aluminium bar for it
To get a sense of scale you can see in my hand a old 5/8 wave silver rod
Let me know what you think or any improvements that can be made
Dave
