80 40 20m home brew portable antenna
[Photos coming shortly!]
Mark has asked me to do a short write-up on my latest creation, a base loaded vertical portable antenna.
Firstly I used one of the many typical designs from the internet but the manufacturing process is totally different.
I made the antenna with what I had at hand so I made the coil former with a piece of 40mm PVC. I used a different wire and diameter and a different antenna. After checking with one of the many online coil calculators I set to work.
Firstly I cut a 10tpi thread on the PVC pipe with my lathe. I chose the thread to suit the end caps. Then I wound on 15m of galvanised 1.5m wire. I made/purchased adapter's for the lower mounting and the antenna mount. The antenna is a 2.9m multi section military folding type.
As you can see from the picture there is a clamp that slides up and down the coil for tuning. A tuner is not necessary nor is an unun. What I discovered is if I leave the clamp at the 80m position I can tune the bands easily with a simple tuner. Bonus.
So this all sits on top of a slightly modified light camera tripod.
So far I have made several Winlink connections with Jenny vk6jen, Terry vk6ttf (who by the way has also made one) and with vk3mit. It does appear to work reasonably well for what it is. It's light, portable, takes up very little space and can be tuned easily.
If anyone needs anymore info please contact me.