In 2002 I decided to build a big 10m monobander for CQWWs. As sun spot cycle
is declining I wanted the posibility to let the antenna grow to a 15m or 20m
Moreover material should be easy to get in Germany and the antenna should
be a 50 Ohms design with isolated elements.
Stefan/DL1IAO helped me a lot and computer-designed a 7ele and 4ele Yagi
for 10m and a 5 ele Yagi for 15m.
For the 4ele I used some parts of a KLM KT34XA, the 7ele was built of new
The boom is 12m long and consists of two 6m long tubes 50x3mm connected
in the middle by a 1m long 55x2 tube.
The 10m elements are made of: 25x2mm (2m) and 20x2mm (2m)
15m is extended with a 16x2mm (1m) tube, which has to be reduced in diameter
on a lathe to fit into the 20x2 tube.
20m elements will finally end into a 12x1 and 10x1 tube.
I used some plastic boards to isolate the elements from the boom.
Here are some details of how I finally built it: