2020
10 element Yagi 144 MHz
I wish to be active omn 2m again, therefore using a mix of information picked from DK7ZB, DG7YBN, YU7EF, G0KSC, G4CQM, VE7BQH, DL6WU, DJ9BV -Longyagis designs because this is simple to build and: High gain, good pattern and acceptable bandwidth. These aims can be realized with a radiation-resistance of 25-35Ohms. Because the 28-Ohm-feedpoint is very simple to match, I use this impedance for my long Yagi.
I have recalculated the optimized lenghts in Eznec; click to enlarge the image
Measurements
In cooperation with PA0A we did some measurements to determine the beamwith and F.B ratio. PA0A is using a Flex6600
and it is able to accurately read the -db scale.
Power output = 2,5W
Antenna hight = 44m
PA0A -- PA1A distance = 21km
Maximum signal strength
@196,6 deg is -27dB
Then turning the antenna CW (180,96 deg) and CCW (214,24 deg) to find the -3dB points.
Resulting a beamwith of 32 deg.
Then turning the antenna CW (174,72 deg) and CCW (230,88 deg) to find the -10dB points.
Minumum signal strength
The turning the antenna CW (16,7 deg) finding the 180 deg Front to back. Result is Max-Min=54-27= -27 dB F/B
click to enlarge for the PDF image
Material
Using NORMAFIX clamps, the cheapest ones bought at Lasaulec in The Netherlands
Because the radiator is made of non metric 12.7mm sizes, (old GAP antenna) I have to drill these clamps to this size.
10mm elements cutting.
Boom
6000mm boom. 40x40x2mm
Using the woodworking center tool
to scratch a center line the middle of the boom, This is usefull when you have to drill straight through a profile.
Mark the distances from the end of the boom using a scratch pen. The BLUE dot is only for reference were the element is situated. After marking the element I have to mark the NORMAFIX clamp holes. 10mm from the center.
Fixing
Stainless Steel Allen Hex Socket Head Cap and self locking nuts M6x70.
continue the line to the other side of the profile and drilling the bottom holes. This method ensures a straight line and straight alignment of the clamps.
Tighten the hex bolts
Problem
Because the boom is 6000mm and the design is 5980mm there is only 20mm space and only 10mm space at the and. I had to find a solution to solve this problem: fixing the clamps very close to the end and using an extender plate made from my scrap tray.
Therefore reason afterwards: it would be better to make a 9 element yagi with a 5000mm boom. No problems had to be solved and it onbly differs 1dB.
