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Author Topic: Bamboo as quad spreaders  (Read 3019 times)
N3QE
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Posts: 2163




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« on: May 10, 2009, 06:45:45 PM »

I work hard to eradicate any sign of bamboo from my yard. Any tiny little shoot gets dug out and I pull out the entire root system lest it take over the yard. (Which is reserved for all other weeds!)

BUT... down at the end of our driveway, next to the highway, there are some stands of bamboo. Some of it is greenish, others more beigish, and there are some pretty sturdy pieces 18 to 20 feet high. It tapers down as it nears the top, and my ham eyes look at it and my ham brain thinks "hey, those look just like fiberglass quad spreaders".

Is Bamboo practical as a homebuilt quad spreader, or just a complete waste of time longevity-and-strengthwise and I should stick strictly to fiberglass etc?

Tim.
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NH7O
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Posts: 126


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« Reply #1 on: May 10, 2009, 07:24:38 PM »

Bamboo has very poor longevity when exposed to the elements. There are many different types, and some are better than others, but none would be considered good for long term use. Bamboo is hard to treat, as it does not have any lateral fibers that allow for paint or whatever to soak in or adhere to the shiny high silca surface. Usually a long tube is used, and the canes are soaked vertically in borate solution. That might get you a few years of use. Clamping the ends requires care so as not to cause cracking.

If you want to try a quad and see what happens without any investment beyond time, then by all means do so. That is what I did when I was in college in NC, and just wanted to experiment. There was a stand of weedy runner bamboo that I used to make a 2 el quad, which worked as long as I was there. Here in my present QTH there are many types of bamboo, some huge, but I would not use any of them for antennas as the experiments are now too time consuming.
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K7KBN
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Posts: 2788




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« Reply #2 on: May 10, 2009, 09:05:37 PM »

Before the advent of relatively inexpensive and quite  durable fiberglass, bamboo was a VERY popular material for quad spreaders.
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73
Pat K7KBN
CWO4 USNR Ret.
K8AC
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Posts: 1466




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« Reply #3 on: May 11, 2009, 04:44:59 AM »

In the early 1960s, we could get surplus bamboo for free from various sources - carpets or area rugs often came wrapped around bamboo.  Hardware stores sold bamboo blanks from which to make fishing poles.  Never tried any sort of preservation techniques on it as it usually didn't survive our harsh winters anyway.  

The best quad construction I've seen is the Hy-Quad marketed by Hy-Gain in the early 1970s.  It used aluminum spreaders with the stranded aluminum wire elements grounded to the spreaders at two points on each loop.  The three driven elements used individual gamma matches (with a common feedline) and the structure held up remarkably well in the high winds of NC.  
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K0OD
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Posts: 2546




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« Reply #4 on: May 11, 2009, 09:04:51 PM »

"The best quad construction I've seen is the Hy-Quad marketed by Hy-Gain in the early 1970s. It used aluminum spreaders with the stranded aluminum wire elements grounded to the spreaders at two points on each loop."

--
I had a Hy-Quad around 1979. It had something like 850 parts, mostly bolts, lock washers and nuts to build the aluminum spreaders. A nightmare to assemble. I quickly realized it was too big for my purpose and sold it cheaply.

Bamboo was the standard spreader material in the 1950s. Very heavy. Carpet stores would give away bamboo poles. Fiberglass is so much nicer.  

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WB6BYU
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Posts: 13171




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« Reply #5 on: May 12, 2009, 06:29:07 AM »

Bamboo is still a good choice for spreaders if you have
a convenient source and can handle the weight.  There
was an article in QST several years ago about how a ham
in the Yukon weatherproofed his bamboo spreaders to survive
several years in harsh conditions.  Part of the process
involved wrapping each spreader end-to-end with black
electrical tape.  (I don't have time this morning to look
up the article, but I'm guessing it was in the 1980s.)

If you cut your own canes, be sure to let them dry before
you use them in the antenna.  That makes them lighter and
less moisture trapped inside if you do decide to wrap them.
Of course, if you have a good supply and the quad isn't
too hard to get up and down, you can built it with some
green ones while the next set are drying in your garage.
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SV1BDO
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Posts: 34




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« Reply #6 on: February 12, 2013, 12:13:02 PM »

I have built a 2 el 5 band quad using bamboo as spreaders in my second QTH in Egio, Greece (KM18AG). I bought the bamboo poles from a local superstore. These poles are already treated with protection from insects and their surface is covered with a very thin film of transparent varnish. The price of each bamboo pole is about 2 EUR, almost 1/10 the price of the more expensive fiberglass poles.

Here in Greece we have not ice or heavy snow, but the sun is very strong, so I decided to paint them for better UV protection using as prime one coat of Varnish Polyurethane and after this one layer of gloss grey paint.

The bamboo poles that I used are about 2,5m long and 20-24mm dia, so I have to add some piece of bamboo to get the required 3,9m length for the 20m band. You can see more photos with construction details in the following Picassa album.

https://picasaweb.google.com/114462418878772045065/BuildingA5Band2ElementCubicalQuad#

The antenna was on the air for about 1 1/2 year. Last winter, it faced one heavy storm without any problems. I have to put it down as I had some problems with neibhors.

As I was totally satisfied with the mechanical performance using the bamboo as spreaders, I am thinking to build on a different site now a bigger, 3 element, 5 band quad using also bamboo as spreaders onto a 18' boom. We are going to use the Cubex 3 el design, modified by Danny ON7NQ. The article is published in Cebik's site.
« Last Edit: February 12, 2013, 12:20:35 PM by SV1BDO » Logged
G7DMQ
Member

Posts: 40




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« Reply #7 on: February 12, 2013, 05:46:29 PM »

I've used garden cane (same as bamboo) for spreaders and it worked pretty well.  Didn't have any issues with degradation over time.  Maybe garden cane is pre-treated?  It's sold by garden centres to support saplings & climbing plants.

It's cheap enough that even if it rots, it's not the end of the world.  Since you have a free supply - it seems crazy not to use it!

Si
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WA2TPU
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Posts: 208




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« Reply #8 on: February 12, 2013, 07:26:56 PM »

To all...
On the bamboo Quads I use to build as a "lad' back in the 1960's....  I just wrapped the lengths with black electrical tape. Where I attached the wire elements I'd build-up the area on the bamboo shaft with more electrical tape and then use stainless steel hose clamps to hold the wire elements in place. I could get about 4 to 6 years out of a bamboo Quad depending how cold and bad the winters were in Upstate New York. Also, I was in "ham heaven" when shrink wrap became affordable and could be purchased readily in large amounts...then it was nothing to make Quads and Delta Loop antennas for 6, 10, 15 and 20 meters. Those were the days when hams built nearly all of their antennas.
Best regards and many 72/73.
Don sr. --WA2TPU --
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W3HKK
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Posts: 596




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« Reply #9 on: February 13, 2013, 05:48:07 AM »

Despite it's imperfections,  you cant beat the price!  My first  quad ( for 15m)  and  a 2nd quad  I used in Ghana were made from   bamboo.  My first   was from  bamboo purchased from a rug store ( commonly used to wrap carpet around..at least in the old days)  and the 2nd one was fresh cut.

They lasted several years before I  moved and took them down. 

I'd say Go for it!  Even if hurricane winds  prove too much, how hard cana it be to replace the broken spreaders. 

Other uses are for ground plane antennas...work great.   Stick them in the end of  aluminum or  fiberglass mast sections or  the longer ie 40m etc antennas.

Good luck
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W4RS
Member

Posts: 64




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« Reply #10 on: February 25, 2013, 05:49:29 AM »

will it work? sure it will, here in the philippines bamboo is used for houses, antenna supports, carts, etc good bamboo is used for scaffolding in asia hundreds of feet in the air.
jim, w4rs/du3
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WA8UEG
Member

Posts: 351




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« Reply #11 on: February 25, 2013, 10:31:11 AM »

In the early 1960s, we could get surplus bamboo for free from various sources - carpets or area rugs often came wrapped around bamboo.  Hardware stores sold bamboo blanks from which to make fishing poles.  Never tried any sort of preservation techniques on it as it usually didn't survive our harsh winters anyway.  

The best quad construction I've seen is the Hy-Quad marketed by Hy-Gain in the early 1970s.  It used aluminum spreaders with the stranded aluminum wire elements grounded to the spreaders at two points on each loop.  The three driven elements used individual gamma matches (with a common feedline) and the structure held up remarkably well in the high winds of NC.  

Put my Hy Quad up in 1970, I have used it at various locations around the US every since. I replaced the aluminum element wire with copper clad steel and the cheap plastic insulators that attached the element wire to the stand offs with durable ones. I also beefed up the rather screwy feed system they used with more rebust parts and the brass screws with SS ones and it's been up at my current location through all the ice and wind of the Pocono Mountains for 10 years now with no problems at all. It works very well on 17 & 12 with a tuner.
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W1JKA
Member

Posts: 1631




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« Reply #12 on: February 25, 2013, 11:24:38 AM »

Re: N3QE

      You did not state for inside or outside use.If for inside use,go for it.As others have said,no problem.My homebrew Bamboo quad from 1964 still resides in the shed chamber of my old family home,not used in 40 yrs.but still in one piece and doing double duty as a support for a hornets nest and seven swallow nests. 
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K4RVN
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Posts: 761




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« Reply #13 on: February 26, 2013, 04:09:37 PM »

Tim,
My first quad was a homebrew tri bander using bamboo spreaders. I prepared the green bamboo by tying a nylon cord at the small end and throwing the cord over a tree limb. Then I tied a brick to the bottom of the bamboo to keep it straight. Once the bamboo dried out, I put a couple of coats of
varnish or shellac over the dried bamboo. They did not last long due to the weight and the wind we had at the time. My advice would be to buy some spreaders from a source like Max Gain Systems and don't waste your effort on the bamboo. They usually split and will collect water and freeze in colder areas. They will do for a time but then you will have to replace bamboo. The spreaders from Max gain can be shipped ups, etc and are not one piece for a large quad. A small quad for VHF may do well with bamboo, but I have not built one of those. Others like Cubex also have spreaders.


Frank
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N0NZG
Member

Posts: 122




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« Reply #14 on: February 26, 2013, 08:23:35 PM »

I made a “ temporary ” 20 meter 2 element wire beam with bamboo for a contest and it lasted 3 years in Kansas’s weather until I moved. I wrapped it from end to end with Scotch 33 electrical tape and it seamed to play well and got me my first European contacts on 20.  As much as I like bamboo I would only use it for an antenna you don’t mind replacing after a couple of years.  Should you desire a long-term solution I would recommend fiberglass as you can get a telescoping fiberglass flagpole or fishing pole from jack-kite and others very cheap. 

Good Luck , 73 Jeremy
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