@John D D Howdy John. No I don't use any matching at all and I don't have any heat issues. I have been running the unit 24/7 for weeks now and I haven't had any problems. They are great little units that Harry has designed!

Howdy Mark! I’m no expert but I just use a piece of wire about 18 meters long with my Zachtek (160 - 20 metres) - Not sure of the exact length. I don’t use any matching at all and I am heard all over the world. If you look back through the previous discussions on this forum, you will see a comment from Harry about this topic. Apparently the further you get away from a matched 50 ohm output, the more the power reduces.

I seem to remember a post from Harry saying, the further you get away from 50 ohms output impedance, the more the Zachtek throttles back the power. I simply use a length of wire (no idea of the length, maybe 18 meters) with no matching at all and I am heard all around the world. (160, 80, 40, 30 and 20 meters) My unit runs 24/7 outside on my balcony and the summer temps are getting up to 35/40 degrees celsius. - The callsign i'm using on my WSPR TX is VK6RSR. - Cheers all.