[P3] Feed support.

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The original (three) feed support bars are made of steel tube. If they were ever galvanized it does not show.


 The feed holder is a heavy, white, plastic ring.

The inner ends of the arms are slit, tapered and lightly knurled where they have only a push fit in the plastic ring.

Three holes are bored at 120 degree intervals for the tips of the support arms.












As purchased, the old, Amstrad, Ku-band LNB, with built in feedhorn, was screwed to the ring via a crude and ridiculously over-sized piece of alloy angle. The head was anything but straight and seemed very prone to accidental flexure. The three holes in the ring suggest it once had a neater clamping plate which would have allowed rotation adjustment for LNB skew.






The arms are now rusted and very ugly. As are the captive fixing screws which fit in small brackets bolted to the outer rim of the fibreglass dish.

I have resolved to replace the feed support arms with good quality alloy tubing. I have also ordered a new central boss of aluminium plate with an LNB clamping ring to allow for skew.

The other advantage of the new central boss is that it will allow firm, screw clamping. While a triangular pyramid (tetrahedron) forms a naturally, very stiff structure it relies heavily on the connection points being firmly attached. The old design was very weak at the top of the pyramid!

I believe that the 12mm OD alloy tubing and threaded clamping at all connection points will provide a much more secure head assembly.


I found these Fischer expansion sleeves in a local DIY store. They fit the inside of my alloy tubing and will expand to lock permanently in place when an inner cone is pressed home by the screw. I don't believe the cone can be retracted once pressed home. The female thread in the sleeve will then hold the necessary screws for support arm fixing. The short M8 stainless steel screws and nuts were bought separately and were not part of the expansion device.

For cosmetic reasons I could saw off the screw heads and have two nuts to clamp to each dish bracket and the central boss. I am still pondering whether to do this. The next post will show the new boss, feedhorn and head assembly. I am now waiting for these items to arrive in the post.   

Click on any image for an enlargement.

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