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Evan,
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Fully agree that the ideal high power amp for the QMX would have about the same organization
as what we have now.? CLK2 feeds the gates of the final push-pull FET's.
Given that EER SSB works, there's little reason to deal with the complications and expense of a linear amp.
Leave that market to Elecraft.
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Should probably be a new design in one box, perhaps call it the QMX++.
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It would be possible to add a connector to the QMX+ (an HDMI cable so it is cheap and impedance controlled)
to carry CLK2, modulator control signals DAC and ADC_PA, tandem match outputs ADC_FWD and ADC_REV,
the band select signals, and the TX, RX, and RX_IN signals out to another box that has a high powered final
plus LPF's and tandem match in it.? Replaces everything on that final schematic page of the QMX.??
Kludgy, but if you want a cheap high volume 5W exciter and an optional amp, it could be made to work
and would be a whole lot cheaper and more efficient than Elecraft's 100W linear.
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But there's plenty more to be done with the QMX before it's ready for higher power.
Higher power won't happen for quite some time.
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The Polar Explorer article from QEX is publicly available from the ARRL website:
That's not just a linear amp replacement, it sends phase modulated RF to a switch mode final
and envelope information to a modulator, those two channels are generated digitally
just like the QMX.? There is no RF SSB signal till it comes out of the final.
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There have been other products doing EER linear amps that take output from a
traditional SSB exciter and split it into RF phase and AF amplitude information
as shown in fig 2 of that polar explorer article.
These have been available for decades, they have been successful in?
commercial SW transmitters of perhaps 50kW or more where the
additional complication is worth the increased efficiency.
The QMX (and the uSDX) have far less complicated hardware, and thus are cheaper.
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Evan said:
"We may be getting too far off-topic and need to start another thread."
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I take considerable pride in being off-topic.
Shows I"m capable of independent thought.? ;-)
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Jerry, KE7ER
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On Wed, Mar 19, 2025 at 09:50 AM, Evan Hand wrote:
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