Re: Possible QMX/QDX PA Improvement Idea
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Good point. I probably didn't run the sim long enough for that effect to show up.
Tony
AD0VC
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Good idea!
Though I'd think a DC bias at the gates of 0v would mean the 5v swing?
is now going from -2.5v to +2.5v, not enough to fully turn on the BS170's.
Perhaps that 2k should go to 2.5v when TX is true, and to 0v when TX is false.
Getting a bit more complicated.
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Could go to a solid 2.5v rail, except that Hans has found reason to keep the?
DC supply to the final on during receive.
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Jerry, KE7ER
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On Thu, Apr 3, 2025 at 05:53 AM, mux_folder2001 wrote:
It occurred to me that the Interface between the ACT08 drivers and the BS170 gates could be AC coupled. A quick simulation with 100nf and a 2k to ground on the gates shows no ill effects. The advantage is two-fold. First, a BS170 failure that puts 12V
on the gates is less likely to damage the ACT08 outputs. Second, any failure that leaves the ACT08 outputs high for a long time is less likely to fry the BS170s.?
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Just a thought.
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