REverse power measurment is not correct

[WM4CH]

I have a thread in the Thetis subforum but now believe I have a hardware issue.

The Reverse power measuring is unrealistically low producing an SWR that is much lower than the actual SWR.

The circuit diagram shows the Reverse Power goes through an opamp, so this is very likely a hardware issue that needs to be sent to Doug.




The SWR is broken on all bands.

I never noticed because I use an autotuner and the autotuner does it's thing fast.

The autotuner is not a 6 meter tuner so I was trying to use the 160 meter doublet to tune to 6 meters and noticed before I even manually tuned (it is a modified Johnson Kilowatt Matchbox that I keep it tuned to 160 meters ) the SWR on the ANAN only showed 1.3 SWR while the stand alone power meter was very high.

That is how I noticed the problem.

Today I checked all the non-resonant bands and the SWR and Reverse power readings on the ANAN are way too low on all the non-resonant bands. As an example it shows only 1.9 SWR when the real SWR on 160m on the 80/40/20/10 fan dipole is over 8.

The reverse power measurement is reading inaccurately low producing a very wrong SWR.
The forward power reading appears correct.

So now I am thinking this is probably another hardware blown component.

[Alex A]

Have you checked the signals coming to ADC78H90CIMT (U17) FWD PWR and REW PWR (J15)?
After establishing the presence of adequate voltage levels, it will be clear whether this is a hardware or software problem ....

[laurencebarker]

It also goes through a potentiometer on the RF board, that may not be set correctly

[Alex A]

I also had problems measuring SWR and reflected power.
Even when setting the minimum output power, it showed 0.3W reflected. And did not change the value when the output increased.
The converter ADC78H90CIMT (U17) did not work properly.
Chip heating 92°C(197.6°F).
Although FWD displayed correctly.
Recently replaced it.
Checked with Thesis v2.10.0x64
All OK......

[WM4CH]

Just seeing the replies now, somehow I lost this thread.

[WM4CH]

Have you checked the signals coming to ADC78H90CIMT (U17) FWD PWR and REW PWR (J15)?
After establishing the presence of adequate voltage levels, it will be clear whether this is a hardware or software problem ....

I will see if I can do that, thanks

[WM4CH]

It also goes through a potentiometer on the RF board, that may not be set correctly

I will look at that too thanks

[WM4CH]

I also had problems measuring SWR and reflected power.
Even when setting the minimum output power, it showed 0.3W reflected. And did not change the value when the output increased.
The converter ADC78H90CIMT (U17) did not work properly.
Chip heating 92°C(197.6°F).
Although FWD displayed correctly.
Recently replaced it.
Checked with Thesis v2.10.0x64
All OK......

mine appears to be at a fixed ratio of 10% displayed compared an external meter.

1 watts reflected, and the radio shows 0.1 watts reflected.
2 watts shows 0.2
3 watts shows 0.3
4 watts shows 0.4
10 watts shows 1 watt

Guess I will send it to Doug after I check the pot