Homebrew

 

This page will show all kind of home made projects. Most of them are easy ones.




YAGI PROJECT.
Due to quite some strong winds I lost the front element of my 5 el. Yagi. So time for a new design. K6MYC made me a design with two stacked Yagi's. But after a try with one Yagi, I decided to go for my own design again. The K6MYC one was difficult to match and I saw a 1 dB loss in gain with my 5 el. homebrew one. I used YO4.9 to develop one that meet my demands and was able to use the M^2 element mount and the M^2-match. This was not easy. And the prototype did not perform as expected. PA7MH Johan, also did do a lot with Yagi's and uses a newer version of YO. I asked him to recalculate my design and the match. After a whole afternoon with many phone calls we came with the result which is very close to the calculation. It seems after many tries that these element mounts do not require any compensation. At least not very much. Also I like the M^2 match solution. It has a N-connector and F-connectors for the 200 Ohm balun. Of course all the (expensive) parts were with American measurements and I needed to fit them for EU standards. So the match mount was made to M8 bolt and the shorting bars were drilled to 10mm. The elements are made of 10x8 mm pipe which has been filled with 7,5mm massive for the first 50mm to get a proper and secure mount with the M^2 element fitting. The elements are tightened with M4 screws and a lock nut. The match legs are standard 56 cm long. The shorting bars were made at 24 cm each side. The boom is 40x37 mm diameter. Because a standard length aluminum is 6 meters long I had to extend it by a meter. I used another length (6 meter) of 36x32 mm that was pushed in the other pipe. So I have a very strong boom that is again supported by a rope. See the foto. All other dimensions are in the drawing. I took quite some time to measure and align the antenna. After the many cuts and pastes to the elements I came to the following measured results:
Return loss: >40 dB
f/b Ratio    : >30 dB
Calculated gain: 9,8 dBD
Gain above ground at 17m: 15,7 dBD
Measurements were made with a Tektronix 2710 for gain comparisment and front to back ratio.
A Bird43 was used for VSWR measurement. But the final measurements are made with my homebrew return loss meter. The result couldn't be measured with the Bird elements any more. With 100 Watt forward less than 10 mW was reflected. Impossible to measure that with a directional coupler.
When you think you need more information on this antenna please feel free to ask. It will be added as soon as possible on these pages.


OLD 5 el. YAGI.

This was my home made 5 el. Yagi.  It is been build by many others and a good performer. I have heard and worked EME with it.  All dimensions in the drawing are in millimeters and centimeters.

HF BALUN.


It is a PA0SE design and perform very good with an open dipole fed by an open feed line.
The balance between the two feeders is perfect. Much better and low loss compared 
to the common used core baluns. Download the ZIP FILE for the full description.
It is in Dutch but I guess the pictures and diagrams are explain enough to build it 
yourself. And don't hesitate to drop me an email when you need some translation.


HV POWER SUPPLY.
For a big amplifier you need BIG power supplies.
Read this article what I wrote for an US EME newsletter and Dutch amateurs. A protected HV power supply.