Category Archives: Mount

Dish Feedpoint Mounts

Tony G8DMU has a 2.4m mesh dish on his van. He uses a variety of feeds, and they are all different diameters. I made up a quick-detach support ring to fit an RF Hamdesign multi-band ring feed, but Tony’s 23cm feed is larger, so I made up some extension blocks and a set of cheeks and spiders to support the different feeds.

The original ring feed, with the adjustable ends on carbon fibre struts, QD sockets and attachment brackets

First step was to extend the ring to fit the large feed

Blocks inserted into the ring to increase the diameter and provide attachments for the spiders and cheeks

I made up a stainless steel internally threaded clamp nut to fit on a stainless threaded bar fixed into the block with Loctite, so I didn’t have to worry about threads in the aluminium getting damaged.

The big 23cm band feed in the clamp ring

Next step was to make support cheeks/crescents to hold the multiband ring feed

Adjustable crescent with a knurled brass head on a pointed stainless steel thread, with a brass insert to spread the force and prevent wear on the Delrin
Fixed crescent, milled from Delrin and threaded M5

The 3.4 GHz feed is the smallest, so I milled a support ring and fitted support rods with threaded ends to fix to the holes in the outer ring. The threads were M5 so they fitted easily through the M6 threaded hole in the clamping block.

Clamping ring and spider for the 3.4 GHz feedhorn
3.4 GHz horn fitted to the main ring.

The 13cm horn is a little larger, and had to be made in two pieces to fit over the backshort.

2.3 GHz feedhorn in the clamp

I milled the rings on my ancient Bridgeport mill using a shop-made fixture plate on a rotary table with a sacrificial plate made from acrylic sheet.

Finally, a photo from Tony of the big dish in use on his van at a portable contest site up in the hills