Call Search
     

New to Ham Radio?
My Profile

Community
Articles
Forums
News
Reviews
Friends Remembered
Strays
Survey Question

Operating
Contesting
DX Cluster Spots
Propagation

Resources
Calendar
Classifieds
Ham Exams
Ham Links
List Archives
News Articles
Product Reviews
QSL Managers

Site Info
eHam Help (FAQ)
Support the site
The eHam Team
Advertising Info
Vision Statement
About eHam.net

   Home   Help Search  
Pages: [1]   Go Down
  Print  
Author Topic: Mast Material  (Read 1043 times)
AB5EQ
Member

Posts: 4




Ignore
« on: January 04, 2010, 08:58:56 AM »

I am planning to mount a Zero Five 10-40 meter ground plane antenna on a steel pipe. I will put 4` of the pipe in concrete with 10` above ground.  The antenna is 26` in overall length and weighs 18 pounds. The mast will be 1 3/4`` OD. I do not plan to guy the mast, just the antenna itself. What should the wall thickness of the mast be?

Thanks,

AB5EQ
Logged
K0BG
Member

Posts: 9800


WWW

Ignore
« Reply #1 on: January 04, 2010, 10:07:37 AM »

The antenna is designed to be free standing, so you don't need to guy it. If you did, you'd have to use Phillistrand or similar material.

Based on the weight, I suspect standard mast material is adequate, but you will have to guy the mast. You could use heavy-wall masting, but it will cost as much as the antenna.

By the way, don't expect miracles from the Zero Five.
Logged

WX7G
Member

Posts: 5691




Ignore
« Reply #2 on: January 04, 2010, 12:43:16 PM »

If you post the antenna diameter and your maximum wind velocity I will calculate the tubing diameter for aluminum tubing. The maximum wind velocity for your area can be found online.

In liu of this I would use thick (0.120") wall aluminum tubing type 6061-T8. A 6' section of 2.00" with a 6' section of 1.75" on top. This makes a 9.5' mast.

Or go 2.25", 2.00", and then 1.75" tubing telescoped for a 14' length. For more strength at the bottom section slip 2.50" tubing over it. DX Engineering sells this tubing.
Logged
KB6VIV
Member

Posts: 195




Ignore
« Reply #3 on: January 04, 2010, 01:07:35 PM »

"You could use heavy-wall masting, but it will cost as much as the antenna."

Oh give me a break!  You can definitely save some money by buying cheaper mast and use guying.  And I would definitely check the ARRL mast formulas, if you do go without guying.  But the zero five 10-40 goes for $469.  I just checked the metals supermarkets website and you can get a 12' 1.75" 6061 aluminum round rod there for $117.  About a quarter of the antenna cost.  You could not convince me that the round rod that I mentioned would fail in this application.
Logged
K0BG
Member

Posts: 9800


WWW

Ignore
« Reply #4 on: January 04, 2010, 03:35:05 PM »

If you want strength, you do not use solid rod. What's more, the shipping for a 12 foot piece of 6160, is nearly the cost of the piece to start with. Been there, done that.

You can buy standard TV mast at Home Depot, Lowes, and most Ace hardware stores. If you guy it, it is strong enough.
Logged

KX0O
Member

Posts: 49




Ignore
« Reply #5 on: January 04, 2010, 03:36:45 PM »

I also guarantee that a single length or two to make 26' will not be 1/4 as strong as the design of the zerofive.  One of the keys to the design is the length of each section and the overlap.  I personally wouldn't elevate the antenna unless required by the location because: 1) elevated radials are notoriously difficult to keep tuned and symmetric, 2) pain to have radials elevated across the location.  The Zero-five is not a miracle but it is a very mechanically simple and strong vertical.  A large contributor to its strength is it's flexibility.
Logged
W5DQ
Member

Posts: 1209


WWW

Ignore
« Reply #6 on: January 04, 2010, 05:47:30 PM »

I highly recommend that you DO NOT use anything like chain link fence top rail unless it is guyed properly if you have any high winds in your area. If you do, be prepared to replace it very soon. I had used a 11 foot piece of 1 3/8" top rail that was mounted on a roof top tripod and had a 4 foot piece of fiberglas surplus masting as a insulator offset for a simple wire antenna. There was minimal weight on the mast, only the 4 ft section and a small wire antenna across the top. After a sizeable wind storm out here in the Mojave Desert with gust upwards around 70 mph, the top rail pipe simply bent in a arc and was pointing to the side instead of straight up. I actually had this same setup on a matching tripod on another building about 85 ft away and it also bent but no as pronounced. Needless to say, I replaced the pipes with a stronger steel setup and guyed the heck out of it. 2 years, several wind storms and still all in place.

Gene W5DQ
Logged

Gene W5DQ
Ridgecrest, CA - DM15dp
www.radioroom.org
AB5EQ
Member

Posts: 4




Ignore
« Reply #7 on: January 04, 2010, 06:58:12 PM »

"By the way, don't expect miracles from the Zero Five."

Why do you say that? Have you ever used the antenna?

Melvin
Logged
K0OD
Member

Posts: 2454




Ignore
« Reply #8 on: January 04, 2010, 09:53:40 PM »

Many on this group have used the ZF or similar tall aluminum sticks.

If you work 80 and 160, be aware that MFJ has just brought out a $250 base tuning unit to improve the very poor performance of those verticals on those two bands. QST just did a 2 part article by AD5X on how to build your own matcher.  My experiments show that such a unit can improve the performance of a 43' vertical by about 11dB on 160 and 3 dB on 80.
Logged
A9KW
Member

Posts: 102


WWW

Ignore
« Reply #9 on: January 04, 2010, 10:04:01 PM »

Name some
Logged
K0OD
Member

Posts: 2454




Ignore
« Reply #10 on: January 04, 2010, 10:05:19 PM »

Oops, I see you're talking about the 10-40 meter version, not the taller antenna some firms are hawking as having 160 meter capability.

VK1OD has modeled the 43 foot sticks in detail. His study is a must-read for anyone considering such an untuned vertical.

http://vk1od.net/antenna/multibandunloadedvertical/index.htm
Logged
KB6VIV
Member

Posts: 195




Ignore
« Reply #11 on: January 05, 2010, 07:41:33 AM »

"the shipping for a 12 foot piece of 6160, is nearly the cost of the piece to start with."

Actually, the nice thing about metals supermarkets is that they have stores in quite a few metropolitan areas.  I bought a 20' length of 2" O.D. x .5" wall 6061 aluminum tube for $275 at a local metals supermarkets.  They delivered it to my door for $20. additional (the store was 20 miles away from me).

As far as rod goes, sometimes the Aluminum rod isn't much more expensive than the same O.D. tube.
Logged
WX7G
Member

Posts: 5691




Ignore
« Reply #12 on: January 10, 2010, 02:44:07 PM »

Given the numbers I received via email here is what is needed:

Given a 26' antenna that is 1.50" O.D. at the base, tapering 0.125" every 5.5' and mounted on a 10' mast that is 2.00" at the base and 1.75" at the top. the antenna and mast are unguyed.

The bending moment at the mast base is 2.0X that at the antenna base. The base of the antenna is 1.50" OD aluminum tubing having a wall thickness of 0.062". The base of the mast is 2.00" OD aluminum tubing having a wall thickness of 0.125". The mast base has 4.5X the strength and is subjected to 2.0X the bending moment, compared to the antenna base. The mast has a 2.25X safety margin. The antenna will yield before the mast.

Guying is not needed if the antenna is rated for the maximum wind velocity. Remember to include a 25% margin for gusting over the national weather service records of the "fastest mile" wind velocity.  

Where is the optimum point to guy the antenna and mast if one set of guy wires are used? This is a subject for a future post. Without further calculations I would guy the antenna 10' from the antenna base. The tension on a guy wire running at a 45 deg angle and with a 60 mph wind is approximately 40 pounds.
Logged
Pages: [1]   Go Up
  Print  
 
Jump to:  

Powered by MySQL Powered by PHP Powered by SMF 1.1.11 | SMF © 2006-2009, Simple Machines LLC Valid XHTML 1.0! Valid CSS!