HF  CHAD Installation

Remote ATU


The remote ATU addition for the CHADs came out of a proposal by a commercial company who suggested my single and triple band antennas could run via an auto ATU. In short, the two closely sited antennas (1.5m apart) have a habit of interacting with each other, so as you can imagine the problems setting up to closely co-sited antennas are endless. Setting up the antennas for minimum VSWR always proved very time consuming. Setting up one antenna is a doddle, two closely mounted antennas always has been a problem. The auto ATU makes the whole job so much easier, and instead of the two antennas running on a total of four bands, I can now extend that number to nine, 80m through to 10m. I no longer spend four hours running up and down ladders to set the two antennas up, the auto ATU takes the burden off my shoulders. I experiment with antennas, so different models are erected from time to time, and these two are returned to the mast and retuned.


The photos here show the two antennas mounted on the one mast some 4m above the ground. Mounting the antennas so close to the ground is a compromise; local byelaws. They are switched with current along the coax and also with power supplied to the auto ATU through some 35m of RG-213 coax away from the shack. It is not a complicated arrangement, and all but a  few components were all sourced from my junk box. The arrangement of switching antennas is all under computer control via Ham Radio Deluxe. The low band antenna (an Aerial-worx DG/DOM 80-30) operates on 80, 60, 40 and 30m, the upper band antenna (an Aerial-worx MF 20-15) is switched in for 20m and frequencies above through the software’s parallel port manager. In addition a 4m CHAD is running along side the HF antennas. There are now two SGC-239 auto ATUs at the mast with the new configuration (5-way remote antenna switch).




Apart from the obvious ability to operate two compact HF verticals in a very small garden over a wide frequency range. I am very proud of the overall performance. I have to admit the system and the antennas are not the holy grail, but they perform daily with contacts on all continents of the world, conditions permitting of course. It does permit me to work on HF, where from a tiny garden I would not have the privilege.