It would seem that a 40+ foot aluminum mast with a grounded bottom
just calls out for a wire from its top, parallel to it, down to a
deck-level feedpoint with a tuner.

Does anyone have any experience trying to do this? Was it any better
than the typical weakening of your backstay with insulators? (I have a
B&R rig, so I don't even have a backstay, anyway. With my very full
roach main, I don't think a copper pseudobackstay will fit, either.)

Fair winds
Al
s/v Persephone

Hi
In doing that how do you provide a more direct path to ground for
lightning protection?
Hmm maybe it wouldnt matter, if the SSB was unplugged during times of
lightning. Then again, could a copper plate thrown over the side for
lightning protection also serve as the ground for the transmitter?


cheers
bruce

On Fri, 09 Apr 2004 13:21:54 +0000, Albert P. Belle
Isle wrote:

It would seem that a 40+ foot aluminum mast with a grounded bottom just
calls out for a wire from its top, parallel to it, down to a deck-level
feedpoint with a tuner.

Does anyone have any experience trying to do this? Was it any better than
the typical weakening of your backstay with insulators? (I have a B&R rig,
so I don't even have a backstay, anyway. With my very full roach main, I
don't think a copper pseudobackstay will fit, either.)

Fair winds
Al
s/v Persephone

In the typical "elephant cage" surveillance/DF antenna array, the
folded monopoles are over a ground plane.

Think of the wire as a ground plane vertical with a vertical shorting
bar (the mast) paralleling it and connecting its top to ground.
(Obviously, the "shorting" only happens at DC.)
_
| |
| |
| |
| |
| |__
| __ 50 Ohm
| |
------ Ground
---
-

It's half a vertical folded dipole, with the wire driven at its bottom
near the mast base by your 50 Ohm coax with grounded shield.

Like any folded dipole vs single conductor dipole, it has broader
bandwidth at its resonant frequency, even without a tuner. Since it
won't necessarily be used around 25 meters, it'll still need a tuner.

It'll also still need to have the mast tied to a good grounding
system. However, most of the mast becomes a thick radiator.

On Sat, 10 Apr 2004 11:26:00 +1200, bruce wrote:

Hi
In doing that how do you provide a more direct path to ground for
lightning protection?
Hmm maybe it wouldnt matter, if the SSB was unplugged during times of
lightning. Then again, could a copper plate thrown over the side for
lightning protection also serve as the ground for the transmitter?


cheers
bruce

On Fri, 09 Apr 2004 13:21:54 +0000, Albert P. Belle
Isle wrote:

It would seem that a 40+ foot aluminum mast with a grounded bottom just
calls out for a wire from its top, parallel to it, down to a deck-level
feedpoint with a tuner.

Does anyone have any experience trying to do this? Was it any better than
the typical weakening of your backstay with insulators? (I have a B&R rig,
so I don't even have a backstay, anyway. With my very full roach main, I
don't think a copper pseudobackstay will fit, either.)

Fair winds
Al
s/v Persephone