Sunday, September 22, 2013

Stacked yagis - getting closer to completing our 5 over 5 stack on 10m

As usual in the summertime our antenna antics take a back seat. Metal is too hot to touch, we are all busy doing other things, and its not until summer is almost over that we get back to work.

In July we already had a lot of the prep work for the tower and antennas done. In fact the yagis were already assembled and we had done some provisional tuning of one of them.

Yesterday we got together to do a bit more work. First, we had to tilt over the tower. Right now its just 6 metres high with a rotator cage and mast at the top

This tower is on a hinged base

We turned the antenna round so we could remove the 1:1 balun and replace it with the phasing lines to the stackmatch, with rf choke coil incorporated

Elias and I each brought our own RigExpert AA-30 analysers

These are great little toys. They are not at all affected by the high level of RF radiated by the cellphone tower nearby. Our old MFJ 259 was completely unusable here. Antenna number one was checked, approved, put up in the air to ensure it was the same at 8 metres high, then taken down and taken off the tower. Antenna number two was put in place and we did the same, putting on the coax and choke assembly and checking resonance.

Both antennas are home made, built to the YU7EF specs you can see here

Next job was to cut and prepare guy wires. The tower had been held up over the summer with provisional ropes.

The tower went back up, and while Elias and I checked out the curves on the analyser, Jose Belar and Vic got to work on terminating the bottom ends of the guy wires.

Here's Belar tightening the tensor clips at one end.

And here's what it looks like after finishing. We did a quick test hooking it up to my car to make sure the SWR on the rig was the same as on the analyser, and also to check there is no QRN problem. I made a quick contact with a UA6 station with the antenna pointed towards the states, seems all is OK.

Hopefully in the next couple of weeks and before CQWW and the wet weather come around, we can put up the complete tower with both antennas, rotator, and stack match.

No comments: