This is tubing like used in the 80M 4-square and the 80M bobtail curtains at W0AIH. The tubes are 20′ long, 5.5″ OD and 1/8″ wall thickness. Each tube weighs about 50 pounds. Great stock for building verticals! We have 34 spare tubes; 11 have the flat flanges on both ends, 23 have that flange on one end. Asking $40 each for the ones with 2 flat ends, $35 for the others. Pictures below:
OLYMPUS DIGITAL CAMERA 
These came from an over-the-horizon radar installation:
Aluminum tubing for sale
We would like to liquidate much of the large stock of aluminum tube in storage at W0AIH. All sorts and sizes, from 1/4″ up to 4″ x 20′ x 1/8″. Some is fresh 6061-T6 but much of it is unknown alloy. Paul could generally find replacement tubing for any part of the dozens of yagis in the air at W0AIH. We are looking for someone who wants a large quantity, and our asking price is $1.00 per pound. We don’t want to have to scrap this stuff.
