Re: Auto Antenna Tuner - MP

Lou W7HV

Page 57 on the US manual states the ATU only remembers tunes that are below 2:1, and for each 10kHz segment.  If the load is greater than 2:1, then you must tune again.  I haven't exhaustively tested this, but that does to be how it works. When switching between memorized tunes, there's very little fuss as only the few necessary relays simultaneously click, unlike the 10 second cacophony that goes on when it's searching for a new tune.

On Monday, March 1, 2021, 3:55:45 PM MST, <wc2s@...> wrote:

I am not certain I understand how the internal antenna tuner on the MP is supposed to work, and would appreciate some help.

When the tune light is on, and I hold the button for one second, I hear the wheels turning and then stop.

I thought that the correct settings would then be “memorized” and returned to after one QSYs and comes back to the original frequency later, as do many external automatic antenna tuners.

However, I never hear the tuner in action again on transmit, unless I initiate it.

To test this, and because I have a SteppIR on autotrack, I thought that perhaps the SWR would be low enough already so that the antenna tuner on the MP would not need to do anything further.  Just to make sure, with the autotrack on I then tuned the MP to the already tuned SteppIR antenna and I heard the wheels turn.  I am not sure that means anything, but I wanted to make sure that the MP itself was tuned to the frequency via the internal tuner.

Now turning the autotrack off, if I QSY to another band where I had already tuned the MP, I thought I should hear the tuner come into action when I initiate a transmission into a purposely mistuned SteppIR antenna.  However, I do not.

The manual refers to a "momentary" press which should turn the tuner on, and a press and "hold" to begin the tuning process.

My experiment above was done with the antenna tuner light on, and theoretically in the circuit.

What behavior should I expect from the antenna tuner on the MP, or what am I doing wrong?

Or is there a problem with the tuner?

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