Army loop tuner

I have built the above circuit/tuner and it is working really well. with just 12 feet of wire in a loop I have worked several stations over the last few days on 40 and 20mtrs with 5 watts on cw with the FT101ZD. I have added a meter to read the current, first peak the loop on receive with c2.Then with a low power of about 5 watts peak c2 and c1 for max current. This will also correspond to a low swr. I could achieve down to 1:-1 on both 20 and 40mts with a loop consisting of 12 feet of wire. I found the same length of RG213 coax using the braid gave the same results but found the tuning a little better, i.e. sharper and so a better 'Q'.

Tuner with a loop made of 12 feet of mini coax, using the braid

Internal view, the torroid and diode etc are part of the current meter. I will add the diagram as soon as i can.

A loop made with RG213 coax with this I worked OK4RQ on 40mtrs with 5 watts, 22:10utc 13/7/2007


Not much to look at but it works, next version will be in a die cast box and much smaller.