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It sounds like your installation may be radio-coax-ATU-coax-xfmr-antenna? If not, full details would be most helpful. If so, how long are the coax runs and how is your counterpoise deployed? Al

Hi Al. I always tune at 5 watts or so, never at full power. I’m not sure what you mean about getting rid of the transformer and connecting the wire directly to the ATU … but maybe you mean

Try getting rid of the transformer and just connect the wire directly to the ATU. Also, if you haven't already done so, see if you get different tune results at reduced power. Al

Hi Marek. I tested the ATU-100 by connecting it to my radio and antenna. I don’t have a dummy load, but a friend does, so I will go through the tests you mentioned. I’m completely new here and

How did you validate that ATU works properly? I used following method - connected 50ohm dummy load and checked that I get 1:1 on all bands at 10, 20, 50, 80 and 100W - connected 100ohm and then 200ohm

My EFHW has a 13’2”~ counterpoise. I don’t know about grounding the ATU — will have to read that page - thanks. Daniel

Is the ATU well-grounded or does it at least have a suitable counterpoise? RF could be getting into the ATU's circuitry. Here's a good read: https://www.w8ji.com/long_wire_antenna.htm Al

I have done some more experimentation here. My EFHW should work on 15m, but 15m has high SWR on my install. Not sure why the EFHW has high SWR on 15m, but the tuner should be able to pull it in -- it

Not sure what your comment about ATU placement has to do with it's ability to tune without RF applied. Perhaps folks could be of more assistance if you could define the problem you're trying to solve.

Hi, all. I finally got my ATU-100 built over the weekend, and I tested it the other day with my 40m-10m EFHW. Because it’s an EFHW, I didn’t really know what to expect (I wasn’t sure it would be

An ATU should always, always, always be placed at the antenna feed point, not, not, behind the txrx.? ? ? ? ? ? ? ? ? ? ? ? ? ? ?Returning to my good, old , remote motor controlled? Z

Eh? the match is between the AMU and the Tranciever not the AMU and the aerial

An easy way to tell is, after the ATU is matched, when you switch between TX and RX, is there any relay clicking that indicate TX/RX changeover relays?? If not, it's highly likely it's using the same

My SGC239 auto tuner says that you tx first, get a good match , key up-you receive. But it does not say that the tx match is the same as an rx match Conclusion: going back to my Z match with remote

An ATU matches the impedance of the load with the impedance of the source. On TX, the antenna is the load and the transmitter is the source. On RX, the antenna is the source and the receiver is the

Who advised you that an ATU can match an antenna without any RF excitation, and did these people provide the physics-defying data to support those claims?

Simply put, an auto atu can ONLY tune a TX, BUT once tuned will enhance receive as the antenna will be tuned for both TX and RX. An auto atu CANNOT tune an antenna for receive.

I have made this question to various people, and many dont agree!!!!! The auto atu needs an error swr voltage, which is missing on rx !

The answer hasn't changed since you asked the same question last August. Al, K2ZN

But only if you transmit first. Karl Heinz - K5KHK