Category Archives: Uncategorized

Dual band POTY Patch for 2.4 and 10GHz on QO-100

This was my first attempt at making a “Patch of the Year” dual-band 2.4GHz circular and 10GHz linear feedhorn.

I used 1.5mm brass sheet and 22mm copper pipe, with a brass adaptor to fit a “Red Rocket” LNB.

The completed patch, using the Red Rocket lens

Clamps for 144MHz EME array

A friend in the Netherlands asked me to make a few bits for his new giant 144MHz EME array

The first batch, sleeves, boom clamps, spigots, boom extensions and collars

Replacement Masthead Rotator adaptor

Mike asked me to make a stronger rotator attachment plate for his telescopic mast. The top section is thick walled GRP with 40mm OD. I made a collar and a central pin to fit inside the tube, and fitted the usual 12mm plate with 119mm PCD 8.4mm holes to fit Yaesu or Kenpro rotators. The collar was put in the freezer and the plate in the oven, then they were aligned and pressed swiftly into position to make a string shrink fitted join.

The completed assembly was fixed in place with gap-filling Loctite.

The completed assembly with original guy ring and stub mast and the internal (invisible) pin
All the things….
Rotator plate top side
Rotator plate underside
Collar and rotator-plate mount. The raised section is 0.03mm oversize for a shrink/press fit
Underside of the collar
HDPE bearing bush with guy plate in place
Stub mast inserted and top half of guy ring bearing fitted
Top side of the collar before drilling the centre hole
Underside of the assembly with guy ring HDPE bearings and retaining ring and centre hole
Complete assembly showing (L-R) stub mast, retaining ring, lower HDPE bearing, Guy ring, upper HDPE bearing, collar and rotator plate
Reinforcing pin to fit inside the GRP mast
Pin in the test stub mast which Mike helpfully sawed off for me to use as a template
Underside with the pin bolted through the rotator plate
The mount in place on top of Mike’;s mast with his Kenpro rotator.

Mandrel to machine large copper tube

A friend asked if I could machine the ends of a soft copper tube around 70mm diameter to be flat and square, and to an exact length. Not easy to hold in the lathe, so I made up some expanding mandrels from engineering plastic.

I made a silver steel shaft with an M12 threads on one end and drilled a centre. The other end mounts in a 12mm ER40 collet and there is a bracing tube so tightening the nut forces the the tapered plugs into the split mandrels and they open and press very tightly against the inside of the copper tube. The mandrels when uncompressed are a tight fit in the tube.

Using this technique allows full access to both ends and the whole outside of the tube for machining and polishing.

The raw tube ready to machine
Split mandrel with a tapered bore and a tapered plug on a threaded shaft
Mandrel in place on the shaft
Mandrels in place in the tube, there is a spacer tube inside to keep the mandrels apart
Finished product