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TOPIC: First TX higher power than normal

First TX higher power than normal 17 Dec 2021 00:48 #1

  • danielwee
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I've noticed a peculiar behaviour. If I've not used the SunSDR2DX for a while, or if I change bands, the first transmission after I do seems to put out more power than specified. This is even with the power limit capped in the "Expert" options. Has anyone else noticed this behaviour?
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First TX higher power than normal 20 Dec 2021 15:33 #2

  • danielwee
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I've now tested this quite a bit and can confirm that this is a problem. This is especially bad if you're using it with an external amplifier because the initial surge can be 4-times the set output power. So for example, after I change bands - with the power set to output 0.3W, it will initially put out anywhere between 1.3W to 2.2W before settling down to 0.3W. This seems to only happen with the first transmission after a band change. I highlight this because someone might blow out their amplifier by over-driving it without knowing. BTW, I have the output set to 0.3W in the "Power Correction" in the Expert tab. I was under the impression that this would be a safe option but, as it turns out, it is not safe. I would like to see a fix for this.

What I usually do now is to put my amplifier in standby and hit "Tune" to get the first transmission out of the way. After that it is okay for that band. This was tested with EESDR2. I've not tested this with EESDR3. I'm wondering if anyone else has encountered such a problem with their SunSDR2DX?
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First TX higher power than normal 20 Dec 2021 16:26 #3

  • VK6NX
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github.com/ExpertSDR3/ExpertSDR3-BUG-TRACKER/issues/11

It was submitted "old way" before Github bug tracker started. Roman have entered it into Github, but did not have a time to translate. I will translate it.

ADD ON: Translated.

Please note that at the moment of submission there was no confirmation yet if this was really bug or just individual DX behavior. Since then the bug was acknowledged. Hence, as it stated in description, and concerning all Alpha-testers (quote): "At this stage and before acknowledgement I would recommend to set max TX limit a bit lower for those who has solid state external PAs."
Last Edit: 20 Dec 2021 16:48 by VK6NX. Reason: add-on
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