I just received my sBitx v3 and it is a major improvement compared to the previous one I had and returned.
I like the new software and the new GUI.
CW is working great and so is ft8.

However I have two problems.
1.? power output in CW is
80m 10watts <<<
40m 31watts
30m 10watts? <<<
20m 12watts? <<<
17m 26watts
15m 24watts
12m 11watts
10m 7watts
can this be corrected?

2. in SSB I only have 2 to 3 watts p.p. output

Thanks and 73

I received my sBitx v3 last week and liking it a lot so far.

I have a related question, so I just add it here

The values in my unit are:

80m: 16W

40m: 24W

30m: 17W

20m: 13W

17m: 19W

15m: 15W

12m: 9W

10m: 8W

Actually, I find these quite OK for IRF510s at 13.8V. My only question is - why is the 20m value so low? It should easily be around 20W like on 30 or 17m.

Attached the hw_settings file!

Thanks and vy 73 Andi, OE4DNS

Hi Andi,

The Scale=value for 20 meters is set for 0.005.? Try increasing it to 0.006 and restarting the sbitx program.? You can edit it with vi or nano.

Each band has its own scale factor.? You can tweak these to get values that are more to your liking.? Be careful not to go too high: 25 watts for bands less than 20 meters, 20 watts up to 15, 15 watts for 15 meters, and 10 watts for 10.

Make minor adjustments; the drive is maxed out if you find little or no change.

73
Evan
AC9TU

Thank you Farhan, The file is attached.

Farhan,

I went to 6 then 7 but at 8 or 9 there was no increase of the power anymore. I left it at 7 and that gives me 17w in a 50 ohms dummy load. I can live with that.
I still have the problem that on every bands the power output in SSB is only 1 to 2 watts on every band. That is with a mike gain of 51.? Above that it starts distorting
very quickly and further increasing the gain it starts oscillating. Any suggestion?

开云体育

Yvon - I think I brought this up previously.? The power output you are seeing for a voice input is the average, which is considerably below peak.? If you have the capability (a decent oscilloscope), try running the audio through a compressor, and compare the input to the output.? This should make the issue apparent.? If you put a steady tone, like whistling into the mike, you will see what I mean.

Gerry Sherman

Sent by the Windows 11 Thunderbird

Thank you Evan, that explain what I noticed, not seeing any increase between 7 and 8 on 20m.

Gerry, thank you for chiming in,? I am aware of that. I did make the measurements with a peak power meter, an oscilloscope and also with a generator driving a speaker with a constant 1KHz sine wave in front of the microphone.

开云体育

Hi Yvon

Investigating a bit further by connecting an external power meter between the radio and dummy load.

Power measurements are spot on for 40 am 80m Bands. From 10 Mhz up the measurements reported by the radio are about 3W down from values measured by the external meter. So in my case the 13W on the 20m Band are more lie 15-16 W in realtiy. Still it is lower than the 30 and 17m Band which is odd.

Increasing the scale factor for 20m to 0.007 increases power to 16W (19 externally measured!)

Should I recalibrate the internal power measurement? It is a new radio and explicitely stated that no calibration is necessary. But I'd not be afraid of doing so ;-)

vy 73 de Andi, OE4DNS

Hi Andi,

There is no calibration for the SWR/PWR meter per band.? If you were to calibrate for 10 meters, then 80 meters would most likely be off.? I believe that most sbitx power measurements are off.? That is the case for my V3.? I use it as a relative measure to verify that the output stages are OK.? I believe it is possible to improve the accuracy with circuit changes, like adding a Faraday shield to the center wire of the SWR/PWR sensors.? This has been done for other radios with the same type of sensor.

Reference info on the sensor:



If higher accuracy is important to you, you could add the code to adjust the scaling for each band.? That is what is done for the drive values.? AFAIK that is not on anyone's list of coding modifications.

73
Evan
AC9TU

Hi!

thank you Paul.
I'll try and report later.

73, Yvon
AE7YD