H_Frame

H-frame EME

In these pictures I would like to show you my work on the H-frame. It is build from aluminum tubing, 48mm outer diamter, 3mm wall thickness. The pipes came in 6 meter length from the supplier, so they had to be cut back to the right stack distance that matches the used antenna's.

Firstly I made 4 clamping plates from aluminum, 6 mm thickness. On these plates with dimension 170mm x 170mm, I fastened the tubes for the H-frame with regular car-exhaust clamps. These come in stainless steel version as well in regular cheap model. I used the cheap version and will see how these lasts. May be a furious storm takes the array down sooner...

Here the H-frame is spread out on the ground behind our house. The tubes still have the original 6 mtr. length. Next job is to measure to wich size the tubes can be cut, taking the clapming-plates for the yagi's into account! For the used 2SA13 and the homebuild antenna-clamps. the two horizontal tubes must be cut th 4.45 meter, the two vertical tubes needs to be cut a bit shorter. The stack-distance will now result in 4.37mtr. horizontal and 4.16mtr vertical.

In the above picture is a detailed impression of the cross-plate that holds the two pipes together in one of the four joints. Because the exhaust-clamps are for exactly the 48mm, there is very good clamp-force to expect.

For a impression on the size of the H-frame I put it upright against the back fench in my garden.

It scared my XYL as I asked her to give me a hand in putting it upright...The central pipe in the frame is only for alignment purposes. It will be the regular rotor pipe that is used now already in the tower. Meanwhile there is steelcable 3mm mounted from the bearing down to the two lower cross-plates. In the above picture this was not installed yet, but because the H-frame is upside down here, the strengtening cables run from down-centre to right and left upper clamp-plate.