19-03-2019, 11:50 PM
Wow lots to read and making headway through it all now. Got the laser out today and measured the trees and distances. If I run a standard dipole (unsupported in the middle) I can get each end of the dipole to about 9m AGL and I can support a maximum length of ~ 30metres. If I bend (drop straight down) the last 5m of the dipole closest to the shack then I can fit a 80m dipole but it will be unbalanced - one end will be turned down and the other end flat.
I was thinking of building a 80/40/20 fan dipole and just folding one end of the 80m element but with no centre support for the balun this tends to sag a bit and the centre is sitting at about 6m instead of 9m so it isn't ideal.
If instead I centre support the balun I can get it up to 13m in the tree and use an inverted V approach but the centre point would not be in the middle of the 30m length I have to play with - the tree is close to the end of the block so no way I can fit the 20metre legs for the 80m element. I can probably fit the 15m legs of a G5RV though and this would seem to be a good compromise option.
Q: With an inverted V (either dipole or G5RV) I know the included angle in the V needs to be greater than 100 degrees but how critical is it that the angle is even? Because the tree I am using is close to the back of the block, I would need the northern leg of the dipole to be a fair bit steeper than the southern leg. The included angle would be about 120degrees but it wouldn't be symmetrical.
Is that likely to work?
I was thinking of building a 80/40/20 fan dipole and just folding one end of the 80m element but with no centre support for the balun this tends to sag a bit and the centre is sitting at about 6m instead of 9m so it isn't ideal.
If instead I centre support the balun I can get it up to 13m in the tree and use an inverted V approach but the centre point would not be in the middle of the 30m length I have to play with - the tree is close to the end of the block so no way I can fit the 20metre legs for the 80m element. I can probably fit the 15m legs of a G5RV though and this would seem to be a good compromise option.
Q: With an inverted V (either dipole or G5RV) I know the included angle in the V needs to be greater than 100 degrees but how critical is it that the angle is even? Because the tree I am using is close to the back of the block, I would need the northern leg of the dipole to be a fair bit steeper than the southern leg. The included angle would be about 120degrees but it wouldn't be symmetrical.
Is that likely to work?