Mounting on a Mast

[VK2HCC]

Hi Guys, I've just put up stage one of my mast which is just a 2" galvanised pipe. Its only 7m at the moment and once I am happy with the mounting I will extend it another 4-6m. I have used a 1m long ground screw as the base and it seems pretty stable (with a few other mounting points)

Anyway my question concerns the mounting of antenna's onto the mast. Stage 1 I will put a metal cross bar onto the mast and then mount the antennas on that cross bar. The antennas will be a Dual band jpole (2m & 70cm) and probably a 2m yagi of some description both with metal bases/booms.

And finally the question/s , Do I need to insulate the booms of the antenna's from the cross bar?

If I get a vertical that needs ground/radials would the connection via the galvanised mast and ground screw provide that earthing?

Thanks for any suggestions

Craig

[VK2GOM]

Hi Craig,

Your installation sounds good.

As far as mounting a vertical on there goes, a lot of verticals (eg. the Diamond X series 'base' range) rely on the bond to the mast to assist with grounding. The radials help further in generating a ground plane.

As far as mounting your Yagi goes - is this a horizontally polarised Yagi? If I am picturing this right, you want to mount this on a horizontal bar, which would be attached the the Yagi boom in line with the elements? This would not help the antenna pattern at all. If you can make some sort of stand-off such that the only ingress into the antenna's pattern by metal supports is at right angles to the elements, this would help. You might be better mounting the Yagi towards the top of the mast (without any cross bars) and leave a bit of mast poking out above and mount your vertical on that.

I am interested in your 1m long ground screw... have you got pictures, and where did you obtain this?

73 - Rob VK2GOM / G0MOH

[VK2HCC]

Thanks for the info Rob, The yagi (when rebuilt) will be horizontal and on a rotator so will have a vertical stand-off/support to connect to.

The ground screws are used in building things such as pergola's and available from Bunnings, I have found the top stirrup section, that would normally hold a 4"x4" piece of timber is a bit to flexible so I will reinforce it with some steel plate..

I have a couple of pictures which I just tried to upload but they are to big, I'll shrink them a bit later today and upload them.

Craig

Photos added

[VK2GOM]

Hi Craig,

Interesting.... I wonder what the inside diameter is of one of those, if I angle grind the top U stirrup bit off?

I bet that would support a mast OK, and then perhaps some sort of supplementary strut a couple of foot above that to further help.

73 - Rob Vk2GOM / G0MOH

[VK2HCC]

Hi Rob, At $25+ a pop I'lll let you take one apart (for science of course). and that is exactly how I have it supported, about 2m off the ground I have a 1" solid steel beam connected to it and the other side of the beam is connected to a 4" verandah post.

Craig