VK5APN (PF95jg)


In the past I have constructed a number of 2m yagi's. With varying success. I wanted one that did not need a boom support and fitted materials on hand.
I decided upon the YU7EF 10 element design. I then emailed Poppa (YU7EF) with my material dimensions and he provided me with the yagi dimensions.

Here is a step by step construction guide to the way I build these fine yagi's

(1) Drill the boom using a drill bit that is a little undersize from the required hole size.

(2) Enlarge the hole to just fit an element with heatshrink on.
I used a tapered round file with a pen mark on it (that was for me to know how far to go). Do this to both sides of the boom.

(3) Cut some heatshrink that can fit snuggly over the element (or can be shrunk down enough for a tight fit over the element).
I provided an extra 5mm of heatshrink either side of the boom. In my case a 35mm length of heatshrink.

(4) Place the heatshrink tubing in the centre of the element and shrink it on.

(5) Push the element with the heatshrink tubing on, through the boom. Make sure that it is centrally located.
Note - this is only a test piece of element, not a SHF yagi element Hi.

(6) Secure the element to the boom using a non corrosive Silicon glue. (I used the "roof and gutter" type).

(7) Here is a close up of the 3 ferrite coax BALUN. I used the FAIR-RITE p/n 26311 02002 Ferrites for the BALUN.
Why 3, because I had them. I did not want to experiment to see if 1 or 2 would be enough.
Gary KB8RQ uses 2 per yagi on his 24 yagi system - visit his web page for details and pics.

I constructed the phasing cables from RG-11. With this connected to the rotator loop cable, I tested the system before mounting it on the tower.
I put two 100 ohm 2 watt carbon resistors on the open ends of the RG-11. That is the ends that would be connected to the Driven Elements.
I then fed some power into it. Checked SWR, that was good. After TXing for a while I stopped TXing and felt the temperature of the carbon resistors.
The temperature felt about the same between the two coax ends. This was satisfying and so then the cable assembly was placed up the tower.

Hope this assists you. Email me if you would like further details, I'll try to help you out.

Use these steps as a guide only, your abilities and particulars may be different to mine.
I do not take any responsibility for damage to you or your equipment.
This is just a fact sharing exercise.

Regards

Wayne