I took down my off-center fed dipole the other day to install the LDG AT-100 ATU on the same mast. Being that the antenna is pretty much at the same height, and oriented about the same as my OCF was, I’m not expecting a big boost in performance, but I figured that the antenna might radiate a bit differently, and maybe allow me to work parts of the amateur bands a bit more efficiently than I had been in the past.
The AT-100 is housed in a weatherproof box similar to the ones you find in a hardware store but has a nice built in bracket that allows connection to a mast fairly simple. I have also seen this deployed in a ‘suspended’ type scenario – as the ATU isn’t too heavy (for those of you that might be interested in the ATU – but don’t have a mast to hang it from).
I connected the output to a DX Engineering 1:1 current balun (experimenting at this point) and ran approximately 170 feet of wire in a ‘sloping’ loop configuration through several porcelain insulators that you find in the electric fence section. I haven’t even checked to see where the loop actually resonates, but it’s a bit longer than a 40 meter full wave loop. I ran a 75′ piece of LMR-400 straight to the shack, and then a 2 foot jumper from the Bias-T controller box into the HF rig. I can tune every band except for 160m – I imagine I probably don’t have enough wire up for that band, though I am planning on making some ‘pruning adjustments’ to see if I can improve the tuning on 80m (can only tune from about 3.700 & up) & on 17m where I can’t get the SWR below 3 to 1.
My very first (WSPR) transmission on 40 meters last night I was heard in France… 20 meters was also hopping late into the night, and I landed Asiatic Russia & Canada on 20 meters on the JT65. I was getting consistent decodes and never using anything more than 5-10 watts, whereas with the OCF I always found myself having to crank up the power more and would get very inconsistent decodes. I don’t want to jump the gun, but it also seems as if this antenna is much more quiet than the OCF! We’ll see how it performs in the next SSB contest as i’m interested to see if it makes a difference in being heard!