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TOPIC: DRIVE and TUNE sliders?

DRIVE and TUNE sliders? 31 May 2022 17:59 #1

  • N0BS
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It seems that the DRIVE and TUNE slider controls have are very nonlinear in operation, like an audio or log taper "pot".
I would find a linear scaling of these to be more useful, especially when setting drive levels for an external amplifier, or just for quickly changing to a desired approximate output setting.
When using an amp, even a 1% change in the slider using the scroll wheel can produce quite a large change in actual PA output.
Is there a way to configure their operation, or might this be changed in ESDR3?
Tnx, Tom
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DRIVE and TUNE sliders? 01 Jun 2022 06:13 #2

  • Rome
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Hi Tom.
To use the TRX with the external PA, you need to adjust the max TX output power per band:
When you use the Tune button in ExpertSDR2/3, with the Tune slider at 100%, TRX sends a carrier signal on the air with maximum output power.
The Tune slider is a special control of the output power for the carrier signal in tuning mode. For all other modes, for normal operations, you should use the Drive slider.
This carrier has a stable amplitude, and you'll be able to set the max output power of the transceiver for each band. Then you can set the Drive slider to maximum and TRX will send the same output power as in Tune mode.
Power correction coefficients are adjustable numbers, they are not equal to real output power e.g., coefficient 50% on 20M does not equal 50W, it can be 60W. Coefficients are not the same for every band, so please be careful and start from lower values. That's how we suggest adjusting output power per band.

Unfortunately, the output power is not linear across all bands. Each band requires its own amplification coefficient for the PA to operate, based on the fact that they are physically different (capacitors, ferrite rings, etc.).
We adjust amplification coefficients so with Drive 100% each band could have about 100W (in case of SS2DX).
Higher Drive values are more or less in line, but lower values below 30-35% vary, at the moment we cannot change that.
Роман, Roman
Expert Electronics
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DRIVE and TUNE sliders? 01 Jun 2022 09:08 #3

  • DF2LH
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Hello roman, thank you for the detailed explanation. I think it would be great if you could include a power setting for with and without activated PA switch. That way you would always have the full power available without the PA active. I have added it to the 'whish list' here github.com/ExpertSDR3/ExpertSDR3-SUGGESTIONS/issues/41
vy 73 Thomas
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