Suggestion on the operation of the ATU

Marcio

After some tests, I realized that a few simple updates will make the ATU more functional.

After turning on the ATU, it tunes based on the frequency you are listening to. But if you change the frequency in the same band, the software will continue to display "Success", even if it is no longer tuned. My suggestion is: every time you change the frequency, the Success option is turned off. If the ATU option is on and you stop moving the frequency, after a while, maybe 5 seconds, it starts to tune back to the new frequency. That way, you will always ensure that the antenna is tuned (if possible).

Marcio - PY5PR

Mike-VA3MW

@Marcio

What version of SmartSDR are you using?

Marcio

@Mike-VA3MW , version 3.2.31.

Mike-VA3MW

Got it. I will pass that on. 73

VE7ATJ_Don

Hmmmm, maybe I misunderstand the workings of the ATU. I thought once the ATU had 'tuned' to a given frequency, it was good for about 200khz or so either side of the tuned frequency. It would only require 're tune' (i.e. no longer showing 'Success') if you tuned beyond that boundary and it didn't already have a memorized tuning for the new frequency.

Did I get that right?

Marcio

I'm not 100% sure in my answer, @ VE7ATJ_Don, but it seems that the further you get out of the tuned frequency, the SWR gets higher and higher, even if "Success" continues to appear, I mean, the ATU does not automatically correct the difference. In my case, at 80m, a small difference in frequency leads to a high ROE.

Mike-VA3MW

You do want to check if your are in ATU MEM mode or manual mode.

Read section 24 of the SmartSDR Manual (or the Maestro manual). There are a number of conditions

After the ATU has found a successful match, the inductance (L) and capacitance (C) values are valid for a 200 kHz frequency span centered at the frequency the ATU tuning operation was initiated, or +/- 100 KHz. Once you tune the frequency of the transmit Slice beyond that range, the ATU will be put into Bypass mode unless there is a previously saved ATU memory at the new frequency.

For high Q antennas that have a very narrow low SWR range, ATU memories may be saved every 10 kHz for a very granular ATU memory profile for that particular antenna.

Marcio

@Mike-VA3MW, I am using the MEM mode. I detected this behavior, but there are several situations, changing band or frequency, where Success is appearing on the screen, but when you try to transmit, the SWR is above 2. The suggestion I gave is to try to resolve or minimize this situation. But it's still a suggestion ... 73s