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 160m inv. L using Clark 12m mast with 12m Spiderpole on top. 
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Post 160m inv. L using Clark 12m mast with 12m Spiderpole on top.
Going to try and get an inverted L up for 160m in the next few weeks. I have a 12m pump up mast with a 2m stub mast at the top. Was thinking about attaching a 12m Spiderbeam pole to that. Couple of questions - is this a bad idea - i.e. has anyone tried something similar and had it fail? Secondly, any suggestions on how much guying it might need? Need to keep guys to an absolute minimum to reduce the visual impact of the antenna but I do live in an exposed location at the top of a hill.

Cheers

Denis MW0CBC / GW8OQV


Fri Oct 30, 2015 2:26 pm
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 160m inv. L using Clark 12m mast with 12m Spiderpole on top. 
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Post Re: 160m inv. L using Clark 12m mast with 12m Spiderpole on
Is this the Scam 12m mast the type that takes two men to lift erected using a compressor
or the lightweight push up type. either way at least 2 sets of guys at the top and lower down.
You have think on what the weather may have in store.
As for the antennas I'll leave that to those who know.

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Fri Oct 30, 2015 3:54 pm
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 160m inv. L using Clark 12m mast with 12m Spiderpole on top. 
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Post Re: 160m inv. L using Clark 12m mast with 12m Spiderpole on
It's the one that takes two people to lift.

Cheers

Denis


Fri Oct 30, 2015 3:58 pm
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 160m inv. L using Clark 12m mast with 12m Spiderpole on top. 
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Post Re: 160m inv. L using Clark 12m mast with 12m Spiderpole on
If its longterm Denis, consider leaving the top two sections retracted as there's a good chance of bending. Not so much it'd be visible but it could at best end up sticky and worst that it'd wouldn't retract at all.

Wouldn't be a issue with small headloads, but with large surface area beams and running a L off it the side load it'd be wise to bear it in mind.

73
Kelvin

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Fri Oct 30, 2015 4:08 pm
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 160m inv. L using Clark 12m mast with 12m Spiderpole on top. 
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Post Re: 160m inv. L using Clark 12m mast with 12m Spiderpole on
Hi Kelvin,

It will only be supporting the Spiderbeam pole and associated inverted-L. No beams or anything else so not a great head load nor too much wind loading....I hope!

73

Denis


Fri Oct 30, 2015 4:17 pm
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 160m inv. L using Clark 12m mast with 12m Spiderpole on top. 
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Post Re: 160m inv. L using Clark 12m mast with 12m Spiderpole on
I'm in the process of doing something similar.....a SCAM mast extended full height with at least another 35ft of heavy duty fiberglass tubing on top. I intend using the SCAM guy lines to support the mast then have two more guy points further up to support the fiberglass with the top set of guys also acting as supports for the 160m capacitance hat (picture the framework of an umbrella without the covering, I'm doing it that way rather than having it inverted L).
BTW, the vertical section will also be trapped for 80m so it'll be a dual bander.....80m & Topband, reason it's not already in place is I'm waiting for the 80m trap to arrive.

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Fri Oct 30, 2015 4:57 pm
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 160m inv. L using Clark 12m mast with 12m Spiderpole on top. 
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Post Re: 160m inv. L using Clark 12m mast with 12m Spiderpole on
Hi Denis

My English at fault I think, what I was trying to convey was the possible issue arising from the side load of running a wire at one direction from the spiderbeam pole atop the scam would cause a sideways pull which may give you an issue in the long term.

The scam has a substantial head load spec, but when it comes to large beams with high windloading or head loads that are not fairly even around the mast then I've known them to bend the top two sections in strong winds.

The problem in all cases was not visible, but the symptom was either sticky deployment or retraction of the sections, or the sections sticking deployed and not retracting when trying to deflate the mast.
When the sections were stripped out and rolled on a flat surface a bend was clearly evident!

Gerry's idea of a top hat vertical is the way I'd go as it results in an equal loading on the mast, topped with the additional guying I doubt if he'll have any of the possible issues I've mentioned :thumbsup:

When I've used large beams atop a scam I've always either retracted the mast before any forecasted high winds or simply kept the top two sections retracted.
I've not had any issues at all by doing this, the scams I have are as smooth in operation now as the day I re-sealed them.
Like you I've got an exposed location on top of a hill, have even had the bottom section of a guyed Spiderbeam vertical snap on me in a winter storm a few years back.

Hopefully I've conveyed what I was thinking.

ps. Hopefully the wx is keeping decent in Chepstow, I'm coming back in a week.

Kelvin

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Fri Oct 30, 2015 7:09 pm
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 160m inv. L using Clark 12m mast with 12m Spiderpole on top. 
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Post Re: 160m inv. L using Clark 12m mast with 12m Spiderpole on
Hi Kelvin,

Everything you say makes sense. I haven't used the SCAM for years but it's been well greased and stored carefully so it should be OK. I Don't intend it to be permanently errected.

I'm not that interested in the lower bands really but when I got my HF licence in 1998 I set a target of nine band DXCC. I've just completed DXCC on 30 - 10m (and rtty) so with a total of only 10 enitites confirmed on 160m I need to sort out a half decent antenna.

Chepstow weather is a little grey this morning but it's dry and mild so nothing to complain about. After some work at home there is a plan afoot which involves a bunch of chaps, Wetherspoon's large TV screen and the rugby world cup final. There may not be too much antenna work first thing tomorrow either!!

Cheers

Denis.


Sat Oct 31, 2015 10:29 am
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 160m inv. L using Clark 12m mast with 12m Spiderpole on top. 
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Post Re: 160m inv. L using Clark 12m mast with 12m Spiderpole on
Good to know I'm not the only one contemplating using the mast/poles in this way Gerry. I can certainly see the benefits of the hat for mechanical stability. I just want to minimise visual impact. Maybe it wouldn't be too bad with thinner guys? Some of the role materials available these days are incredibly strong in proportion to their diameter.

Cheers

Denis.


Sat Oct 31, 2015 10:41 am
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 160m inv. L using Clark 12m mast with 12m Spiderpole on top. 
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Post Re: 160m inv. L using Clark 12m mast with 12m Spiderpole on
I'm using 5mm guy rope bought from the German seller at Newark Hamfest. Its actually been up guying my Hilomast for over a year now and gone through many gales and storms. The other end on two of the guys is just attached to eyelets screwed into the wooden fence adjacent to the concrete fence posts. So far it survived 80MPH gusts without issue.

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Sat Oct 31, 2015 5:02 pm
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 160m inv. L using Clark 12m mast with 12m Spiderpole on top. 
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Post Re: 160m inv. L using Clark 12m mast with 12m Spiderpole on
I'd be interested to see how you would attach a 12M Spider pole to the top of a SCAM 12?
Not that I doubt you can do it, but very interested, as I have two SCAM 12s.

Stewart


Mon Nov 16, 2015 10:17 am
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 160m inv. L using Clark 12m mast with 12m Spiderpole on top. 
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Post Re: 160m inv. L using Clark 12m mast with 12m Spiderpole on
Sorry for the late reply. My plan is the use a 2m stub mast in the top of the SCAM and use a couple of U bolt style brackets to attach the Spiderpole to that. No idea of this is a sensible thing to do but that's the plan!

Cheers

Denis.


Sun Nov 22, 2015 10:55 am
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 160m inv. L using Clark 12m mast with 12m Spiderpole on top. 
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Post Re: 160m inv. L using Clark 12m mast with 12m Spiderpole on
MW0CBC wrote:
Sorry for the late reply. My plan is the use a 2m stub mast in the top of the SCAM and use a couple of U bolt style brackets to attach the Spiderpole to that. No idea of this is a sensible thing to do but that's the plan!

Cheers

Denis.


Food for thought, consider sleeving the Spiderbeam over the stub mast and using something like a rubber mat wrapped around the stubmast to bulk it out the same diameter, that way the fixing point is much more elongated and not relying on metal clamps applying pressure to small areas, the rubber will also absorb some of the abuse it'll get. A set of guys higher up the Spiderbeam pole will prevent it popping off. :)

PS, there'll be a good bed of rubber surrounding it as the SCAM accepts a 40mm mast and the Spiderbeam is much wider than that.

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Sun Nov 22, 2015 11:30 am
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 160m inv. L using Clark 12m mast with 12m Spiderpole on top. 
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Post Re: 160m inv. L using Clark 12m mast with 12m Spiderpole on
How is your antenna coming along Gerry???

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Sun Nov 22, 2015 11:42 am
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 160m inv. L using Clark 12m mast with 12m Spiderpole on top. 
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Post Re: 160m inv. L using Clark 12m mast with 12m Spiderpole on
ei2glb wrote:
How is your antenna coming along Gerry???


You wouldn't put a milk bottle out in this weather so it's at a stand still.
I attempted mounting it on the SCAM a couple of weeks ago using a platform stepladder but chucked it in favour of using a scaffold which I still haven't got.
I'm butt ending 2 lengths of the fiberglass i use for Quad spreaders, heavy duty and not overly heavy to carry but once upright if they move off the perpendicular there's no holding them so a good footing is essential....hence a scaffold around the base of the SCAM.
Everything's here, the fiberglass, the trap, the guy ropes, all fixings....all i need now is time and decent weather to coincide with a weekend.

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Sun Nov 22, 2015 12:18 pm
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