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Mast Material

R

rfoverlord

guardian of freedom
Jun 1, 2005
752
5
28
daegaba system
Okay i'm cheap trying to figure out what a good substitute for chrome moly is. will be stacking 10.1sq. 24 ft. boom 38ft.ele. HF 3 sq. 12 ft. boom (2mtr.) & 2sq. 8ft, boom (70cm.) with a vertical stick 6 ft of seperation between the HF and the 2mtr/70cm. ants on a cross boom and the the vert. will be at least 3ft above those. so thats at least 10ft. coming out of the tower would like the rotor at least 4 ft. in.
Just trying to find out what everyone with the biguns are getting away with. :unsure:
 

I thought there was/is a specific formula for stacking antennas. I read an article recently, but I can't seem to remember where now.

Oh yeah, there was a good article on this subject at the ARRL website. Definitive and complete - might check there. Can't seem to find it now...
 
Either 1" or 1 1/4" galvanized water pipe, buy a 20' length and cut it to what you need.
The 1 1/4" will be stronger, but you need to check if your "U" clamps will fit around it, and if it'll fit into your rotor, if not then get the 1" pipe.

Just remember that galvanized water pipe....also known as iron pipe....goes by inside diameter, so the outside diameter runs larger than the stated size.
1" pipe will have an outside diameter of 1 1/4", and 1 1/4" will run about 1 1/2".
 
WX2MIG said:
Either 1" or 1 1/4" galvanized water pipe, buy a 20' length and cut it to what you need.
The 1 1/4" will be stronger, but you need to check if your "U" clamps will fit around it, and if it'll fit into your rotor, if not then get the 1" pipe.

Just remember that galvanized water pipe....also known as iron pipe....goes by inside diameter, so the outside diameter runs larger than the stated size.
1" pipe will have an outside diameter of 1 1/4", and 1 1/4" will run about 1 1/2".
Click to expand...
actually i would need 1 1/2 in. for outside diameter of 1 15/16 or close to 2 in. which is what i would need for close to the correct diameter. looking more for past practice users with big antennas.
 
With a total windload of 15 sq ft I would not even consider 1 1/4 or 1 1/2 water pipe. Black iron pipe with an OD of 2 inches will handle it IF the big HF antenna is mounted just above the top of the tower.It is the leverage caused by a tall mast that is your worst problem.Black iron pipe will have a little "bendability" to it without it breaking.I presently use a piece of 2" OD black iron pipe with my tribander at the top of the tower with a six element 6m yagi above it and an 11 element 2m yagi above that.
 
OK then.....if you need something closer to 2", then 1 3/4" iron pipe should do the trick, I was basing my guesstimates on the fact that my Ringo Ranger comfortably slips right over 1" pipe with an outside diameter of approx 1 1/4"......

In retrospect, stacking a couple of beams and a stick on top would create a hefty wind load that would bend 1" pipe right over, 1 1/2" pipe would stand a better chance, but it too would probably not take much of a stiff breeze before it would fail to hold up that much antenna.....

I've always said I'm not the sharpest tool in the shed......:blink:
 
QRN said:
With a total windload of 15 sq ft I would not even consider 1 1/4 or 1 1/2 water pipe. Black iron pipe with an OD of 2 inches will handle it IF the big HF antenna is mounted just above the top of the tower.It is the leverage caused by a tall mast that is your worst problem.Black iron pipe will have a little "bendability" to it without it breaking.I presently use a piece of 2" OD black iron pipe with my tribander at the top of the tower with a six element 6m yagi above it and an 11 element 2m yagi above that.
Click to expand...

So how big is your tri-bander (boom length) and your six mtr.? Basically I'm going to have the hf within 1ft. of the top of the tower a tennadyne T 10. the 2mtr. and 70cm. will have vertical elements so i would like to keep them at least one wave length (2mtr.) above it.
I'm just trying not to have to truck in a mast still have to check some of the local metals yards.

WX2MIG,
I've always said I'm not the sharpest tool in the shed......:blink:
But at least your a tool, and still have some use. I appreciate yours and anyone elses replies, as it might cause me to look at things differently from another set of eyes on it.
 
I know it doesn't seem like it, but you would be a lot better off making a mast that long out of the best metal you can find. Sure beats having to fix whatever would get broken if it wasn't strong enough. When the cost of that mast gets close to the cost of all the antennas on it, then you might start being a bit more 'frugal', sort of. Not sure if that came out right, been one'a them days.
- 'Doc
 
First of all I would not use any water type or gas line pipe for a mast your just asking for troubles.If your just swinging a few square ft of antenna it might be ok ????looks like
you are up to about 9- 1/2 sq. ft of antenna.you could use s.s well pipe,be much better than plain old galvanized water pipe or blackpipe,you can get this in 1/8-3/16-1/4 in. wall
thickness in whatever length you need,or you can install 1 pipe inside the other.Iam using
a Nello Nicromium 2-1/2 dia. X 1/4 wall thickness X 10 ft L. mast Iam loading it with a
Mosley pro 67-C-3 at 14 sq. ft ,antenna is 138 lbs on a US Towers HDX 70 crank-up-I get
some bad winds off Lake Superior.Needless to say I purchase a " Real" mast and save you a lot of Greaf and $$$$ -work -1 1/2 NC x10 ft X 3/16 around $150-200 from Nello Corp.
Good luck-Take Care-73/DX

K8PG -Paul CW LIVES-CW IS!!!!
 
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If the large HF antenna is mounted directly above the top of the tower almost anything will be suitable for a mast as it will not bend if it is only about a foot long above the tower. It would have to be sheared off and that just won't happen before the tower collapses.The thing to consider in this case is what's above the HF antenna. If the mast is not too long or the loading not large then black iron is more than enough.Waaaaay back in my 11m days I had a Wilson Shooting Star on 15 feet of 2 inch iron pipe on a hilltop exposed to God's amount of wind and it never bent.A simple 2m and 70cm yagi with a verticle on top of a 10 foot mast will never be a problem if, I say IF, the HF yagi is mounted no more than a foot or so above the tower top.I have my A3 about a foot above the tower with a six element 6m yagi about 5 feet above that and an 11 element 2m yagi another 5 feet above that again on 2 inch OD black iron pipe. It survived Hurricane Juan a few years ago without a hitch.
 
rfoverlord said:
The antenna is a tennadyne t 10 10 sq. and 2 gulfalpha's on a crossboom another 3sq. and a vert. tribander. the t 10 will be within 1 ft. from top of tower.
Click to expand...

OK fine. The T-10 is going within a foot of the top so that is not really an issue. What model are the Gulfalpha antennas and how long is the crossboom? Also what model is the vert. tribander and what bands does it cover?
 
just goto your local metal distributor and buy a section of aluminum tube. it ranges in wall thickess from a sheet of paper to inches thick, i use 1/8" wall and you can get any size you want, it comes in 12ft lengths... whats so complicated? Iron pipe? it would weight 50lbs. stop kidding me.
 
linearone said:
just goto your local metal distributor and buy a section of aluminum tube. it ranges in wall thickess from a sheet of paper to inches thick, i use 1/8" wall and you can get any size you want, it comes in 12ft lengths... whats so complicated? Iron pipe? it would weight 50lbs. stop kidding me.
Click to expand...


Yeah, a lot of guys with big wind loads use aluminum masts. :blink: Sorry I just woke up and read what I wrote. :headbang I refuse to use an aluminum mast over a few feet long unless it had ¼ inch wall thickness. I have seen several antennas lost because of either an alumimum mast or using chain link fence top rail as a mast. With ten feet of that stuff you are just flirting with disaster. The weight of an iron or steel mast should not be an issue as far as the tower/rotator goes as the thrust bearing should take care of it but I will admit that getting it up for the first time can be a tad tricky. BTW all the really big guns with stacks use chromolly masts or carbon steel and not aluminum for a reason.
 

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