Adjusting the TX PWR on ART120


gcoxuk@googlemail.com
 

Hi,
I’ve posted this before, but adjusting input attenuation (IN-ATT) 3db makes no difference in output power. If I adjust the FDM-DUO driving power from 5w to 2w,
The result seems to be an TX power of ~100w (down from full 120w on 40m).
I’m confused, both of these adjusts independently on one another should result in ~50w TX power.

What am I misunderstanding or haven’t correctly set up??

Thanks
Geoff


Kevin Larcombe
 

Hi Geoff,

I have found that the power meter on the ART120 lies like a cheap watch, and the mode also makes a difference. 

I wonder if you are using FM mode for the carrier? If so, try those tests again using AM and SSB mode, the results you will find are very different.

My results on 20m band measuring with the Elad power meter and an external power meter (Uncalibrated) in FM and then AM mode are:

FM 5w 0dB Elad 120w ext 150w
FM 5w 3dB Elad 120w ext 150w
FM 5w 5db Elad 120w ext 140w

FM 2.5w 0dB Elad 120w ext 145w
FM 2.5w 3dB Elad 120w ext 140w
FM 2.5w 5dB Elad 120w ext 120w

AM 5w 0dB Elad 120w ext 140w
AM 5w 3dB Elad 120w ext 115w
AM 5w 5dB Elad 90w ext 80w

AM 2.5w 0dB Elad 120w ext 120w
AM 2.5w 3dB Elad 70w ext 60w
AM 2.5w 5dB Elad 38w ext 35w

It's a great receiver, with an afterthought of a transmitter and amplifier tacked on that they haven't integrated.

Kevin GW0PUH


gcoxuk@googlemail.com
 

Thanks Kevin,
...I suspected something here.

I’m starting with HF CW so AM.  Thanjavur for the useful response.  The other irritating thing about the DUO is that it has no band change setting!  I’m using up what little mechanical resilience there is in the VFO encoder; it’ll soon be worn out.  Presumably when controlling via WIN10 device (another awful thing) I can easily jump bands.

Kr
Geoff
M7COX


On 24 Apr 2021, at 15:52, Kevin Larcombe <kevlarcombe@...> wrote:

Hi Geoff,

I have found that the power meter on the ART120 lies like a cheap watch, and the mode also makes a difference. 

I wonder if you are using FM mode for the carrier? If so, try those tests again using AM and SSB mode, the results you will find are very different.

My results on 20m band measuring with the Elad power meter and an external power meter (Uncalibrated) in FM and then AM mode are:

FM 5w 0dB Elad 120w ext 150w
FM 5w 3dB Elad 120w ext 150w
FM 5w 5db Elad 120w ext 140w

FM 2.5w 0dB Elad 120w ext 145w
FM 2.5w 3dB Elad 120w ext 140w
FM 2.5w 5dB Elad 120w ext 120w

AM 5w 0dB Elad 120w ext 140w
AM 5w 3dB Elad 120w ext 115w
AM 5w 5dB Elad 90w ext 80w

AM 2.5w 0dB Elad 120w ext 120w
AM 2.5w 3dB Elad 70w ext 60w
AM 2.5w 5dB Elad 38w ext 35w

It's a great receiver, with an afterthought of a transmitter and amplifier tacked on that they haven't integrated.

Kevin GW0PUH


Kevin Larcombe
 

Hi Geoff,

I use mine with the SW2 software, I know others swear by other flavours of software. One thing I can say is, that if you try SW2 you won't go back to using the radio standalone. The spectrum display and the ability to tailor the filters, the auto notch and noise reduction are fantastic, I'm sure you would find it fantastic for CW operating. I don't bother with the advanced TX functions in SW2, I prefer to plug the microphone into the radio for reliability and a proper PTT. As I said, I think it's a wonderful receiver let down by poor TX functionality and amplifier integration.

If you want me to make any further measurements as a comparison let me know, I was outside most of the day doing antenna work so did those measurements while I came inside for a quick cuppa.

Regards

Kevin GW0PUH