Use multiple wires, cemented to circumference, ID or OD, to create a
'cage' to broaden the bandwidth.
I have three antennas, up to 58', that I use for field day, made of
telescoped 3" and 2" aluminum irrigation pipe. One person can erect any
of them. They are telescoped with two aluminum bushings, one fastened
to the bottom of the 2" and fitted to slide inside the 3", and the other
fastened to the top of the 3" and fitted to slide over the 2". A 20
meter 5/8 wave, with tuning network at the base and a set of radials
attached to a 4' X 4' aluminum plate under the antenna will show you
what the attenuator is needed for!
When telescoped to minimum length, just over 20', these can be carried
on a car top.
Bases are tripods holding 3" plastic pipe, split so it can clamp to the
3" aluminum. I intended to make stainless coupling sleeves, but didn't
have time the first year, so used copper flashing. It rained Saturday
evening, and oxide was heavy next day in the joint of aluminum to
copper. Used OxGuard next time, just to see, and had no more trouble
with oxide. Copper was nice to solder to a lead to a UHF connector.
Worked so well, I never changed them.
I did put one up for a base station for a time. It stood OK, but I
worried about wind, so I added guys. It buckled about 10' above the
base in a moderate wind as a result of combined bending and downward
load of the guys.
73 de WO?W
Jim W7RY wrote:
>A plastic vertical ?
>
>Hmmmm... What were you going to use for a radiator ? Put a piece of wire
>inside of it?
>
>The "weld" of PVC conduit is stronger than the pipe itself. It makes the 2
>pieces of plastic pipe 1. The US has been using plastic PVC gray conduit for
>years!.... Great stuff!
>
>
>Good luck!
>73
>Jim W7RY
>
>----- Original Message -----
>From: "Chris BONDE" <ve7hcb@rac.ca>
>To: "Jim Hill" <w6ivw@cox.net>
>Cc: <towertalk@contesting.com>
>Sent: Friday, March 21, 2003 3:43 PM
>Subject: RE: [TowerTalk] mechanical construction of 80m vertical
>
>
>
>
>>I have been unable to find a supplier of irrigation tubing within a
>>reasonable distance.
>>
>>The other metal tubing that I have been trying to find out more about,
>>
>>
>and,
>
>
>>in some cases have found that they are good but expensive, are;
>>
>>
>electrical
>
>
>>conduit used for the stack, ie that part above the roof line ($$$$$),
>>industrial grade top rails for chainlink fencing, looks good but shipping
>>the problem for me 20ft lengthas about CA$30 a length, the last was custom
>>automobile exhaust tubing, comes in various sizes, can be welded together
>>or flared. Should be galvo on the inside as well.
>>
>>The other one that took my notice was the new plastic electric
>>conduit. Have to use the large diameter to obtain wall thickness and
>>
>>
>donot
>
>
>>use the coupling, use a length of the main pipe as a splice or spint over
>>the joint. I was wondering about plastic welding, is that as strong as
>>
>>
>the
>
>
>>main pipe as it is in steel pipe welding?
>>
>>Chris opr VE7HCB
>>
>>
>>At 02:45 PM 2003-03-21 -0800, Jim Hill wrote:
>>
>>
>>>Finding tubing isn't easy. I've stopped at a number of businesses in
>>>farming areas with little luck. plastic tubing seems to be currently
>>>
>>>
>used.
>
>
>>>However, the following store in Bakersfield CA is a good choice:
>>>
>>>The Irrigation Store, 4001 State Road, Bakersfield, CA 93303 661-4421 or
>>>800-742-7246. Their web site is: http://www.rainforrent.com/ Their web
>>>site shows tubing with end connections, but I thought I saw just plain
>>>pipe when I visited them. The web site also shows stores at other
>>>
>>>
>locations.
>
>
>>>73's Jim
>>>_______________________________________________
>>>
>>>See: http://www.mscomputer.com for "Self Supporting Towers", "Wireless
>>>Weather Stations", and lot's more. Call Toll Free, 1-800-333-9041 with
>>>any questions and ask for Sherman, W2FLA.
>>>
>>>_______________________________________________
>>>TowerTalk mailing list
>>>TowerTalk@contesting.com
>>>http://lists.contesting.com/mailman/listinfo/towertalk
>>>
>>>
>>_______________________________________________
>>
>>See: http://www.mscomputer.com for "Self Supporting Towers", "Wireless
>>
>>
>Weather Stations", and lot's more. Call Toll Free, 1-800-333-9041 with any
>questions and ask for Sherman, W2FLA.
>
>
>>_______________________________________________
>>TowerTalk mailing list
>>TowerTalk@contesting.com
>>http://lists.contesting.com/mailman/listinfo/towertalk
>>
>>
>>
>
>
>_______________________________________________
>
>See: http://www.mscomputer.com for "Self Supporting Towers", "Wireless
>Weather Stations", and lot's more. Call Toll Free, 1-800-333-9041 with any
>questions and ask for Sherman, W2FLA.
>
>_______________________________________________
>TowerTalk mailing list
>TowerTalk@contesting.com
>http://lists.contesting.com/mailman/listinfo/towertalk
>
>
>
>
|