It was a long weekend and the weather was fine. Sunny and warm. Time to test the 40m antenna.
Note for myself : build or buy an antenna analyzer. Try not to dismantle the whole shack for antenna testing again.
First thing I did at my parents is to solder all amp connections. Then assembled everything together and started searching for a deasant pole. The mount for the pole is fence wire (correct word ?) waiting to be used (See the pictures).
The first readings between the 2:1 SWR points are 6319 and 6372 kHz. That is about 53 kHz usable bandwidth. Keep in mind that the antenna is mounted near/on the ground and has metal close by.
After tweaking the outer elements I managed to get these outer limits : 7012 and 7065 with the center around 7038. Near the center of the PSK activity. I am not fan of voice communications, I like PSK31 more, good enough for me 🙂
The total length of the antenna is about 8 meter. Will the bandwidth raise if I make the antenna longer ?
Back to the K7MEM site and start modelling. The inner elements are now 2,85 meter. I added 65cm on each inner element. It now has a bandwidth of 60 kHz. We just won 7 kHz….
Not much compared to the length we added. I’ll stick to the first length of 2,85m.
It has a practical use : the mounting pole can be smaller.
Part 3 of this project will be written if the antenna is installed on the roof, probably in june or july.
I’ll first have to build a remote antenna switchbox because I will not run 5 or 6 coax cables in a small ventilation shaft.