HUGH
10-23-2023, 11:05 AM
I have a horizontal delta loop of some 220ft x 158ft x (82ft across the far end). The wire was stranded copper of 4mm cross-sectional area (0.006 ins) with PVC coating. The height is 50ft so the feeder was about 40ft long of the same wire (coarse stranded for electrical wiring) and 8 inch spacing. The whole had about 6 ohms resistance.
This worked well for about 20 years but stretched considerably requiring hoisting up on the support pulleys each year. I was a little lax about the concentric fibreglass support pole at the shack end of about 2.5 inch diameter, only using one guy rope and a half-hearted "stiffener" halfway up to stop bowing. The copper was considerably heavy so naturally the pole eventually disintegrated in a storm so I thought of Kevlar-reinforced only to find that here it's only available in 50m lengths and it's quite expensive.
I bought some ultra-flexible steel wire with a PVC coating, it is much lighter but the antenna resistance is about 20 ohms and the feeder spacing (copper wire) is now 6 inches. I find the antenna current to be about half and the results comparatively inferior. Enquiries of some local hams showed some had tried galvanised steel fencing wire but I suspect these were not principally current fed like mine.
The new pole is the same 2.5 inch with 2 guy ropes in the proper place plus a "stiffener" (no comments please) about half-way up. Any comments welcome.
This worked well for about 20 years but stretched considerably requiring hoisting up on the support pulleys each year. I was a little lax about the concentric fibreglass support pole at the shack end of about 2.5 inch diameter, only using one guy rope and a half-hearted "stiffener" halfway up to stop bowing. The copper was considerably heavy so naturally the pole eventually disintegrated in a storm so I thought of Kevlar-reinforced only to find that here it's only available in 50m lengths and it's quite expensive.
I bought some ultra-flexible steel wire with a PVC coating, it is much lighter but the antenna resistance is about 20 ohms and the feeder spacing (copper wire) is now 6 inches. I find the antenna current to be about half and the results comparatively inferior. Enquiries of some local hams showed some had tried galvanised steel fencing wire but I suspect these were not principally current fed like mine.
The new pole is the same 2.5 inch with 2 guy ropes in the proper place plus a "stiffener" (no comments please) about half-way up. Any comments welcome.