These surplus high power PAs using 4 x MRF151 were originally used in watercooled industrial VHF drivers. The devices and some of the other components protrude about 2mm below the PCB lower surface.

To minimise the amount of copper required, I decided to make a heatspreader to go under the devices and make aluminium spacers for the rest. I also decided to make a fixture to hold the spreaders so I could cut neat pockets for the devices. Not sure that was a sensible approach. It certainly meant I had to do some tricky machining.

I have some more to make, I won’t be doing the fancy pockets this time, just transverse slots.

Tony’s 1.2m mast has a figure-8 style extrusion for the feed arm, so clamps need to have two holes and a centre relief. For the new dual-band horn mount, we needed a bit more length, so I made up some extension plugs from aluminium

Someone was asking for advice about hope to connect a tapping point to a big coil made from 8mm copper tube. I came up wiht this solution. The copper hook and brass thumbscrew were made from bits in my scrap bin. There is a hole so a wire can be soldered to the hook.

I wanted to avoid an extra plug/socket on the LDF1-50 coax feed from the 5.7GHz horn to the masthead transverter/PA, so I used a plastic cable gland, but there was still too much movement. This clamp bolts to the inside of the steel masthead box and holds the coax rigidly so I can plug directly into the coax relay without any danger of movement and fracture.

I found a cheap surveyor’s tripod on ebay and made up a new screw and mounting adaptor to fit a short 2 inch stub mast. The original locking screw was trashed.

KBQ is in IO80LX (Taunton) and I can often hear it, but this evening is is hugely loud.

The new 5.7GHz system is ready to mount on the dish, on top of the SCAM12 pump-up mast with the tilting 95cm offset dish and 10GHz system. I’m using a Schneider IP66 rated case made from mild steel with a powder-coated finish. I’ll be adding cable glands and a Gore-Tex breather plug, and flushing the case with dry Argon, and adding a silica gel pack before it is locked and fitted on the mast. The existing 10GHz kit is in an identical case, but I’ll be moving it to the new dish, which has a -7 to +57 degree elevation drive and well as 450 degree azimuth rotation. Initially, I won’t fit the 12W PA, as I haven’t finished it yet, but everything else is sorted and will go in the box tomorrow.

I downloaded Fusion360 this afternoon and decided to try to create a CAD model of the DF9IC heatspreaders I make. Here is the CAD version, then the real thing. Fusion360 is a fantastic piece of software and it is free for hobbyists.

The RSGB have now published my talk on their Youtube channel. Click here to view it.

The source of the presentation can be downloaded here G4DBN FT8 Talk RSGB 2018

As I have two sets of SCAM12 pump-up mast legs, one original, and one set I made, I thought to might be useful to make a cage so I could use them with a 2 inch aluminium mast for when the 90kg of SCAM12 is too much to haul about.

SCAM legs being put to good use

Simple cage with 1 inch steel box sections to fit the SCAM legs

Turned pins and snap-rings to lock the legs in place

I didn’t have any 3/8 inch roll pins so used a bit of M8 threaded bar instead.  The cap bolt is to lock the cage in place during deployment.

The cage is just made from scrap I had kicking about in the machine shop.

At the top of the pole, I use a nice simple collar and slip-ring/guy plate arrangement.  This is for a base-mounted rotator of course