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Hi
What if
You take the power transistors out?
and?
use 74ACT68D's output to drive the 10Watt PA?
Through the LPFs of course
73 DE muhsin TA1MHS

2nd thought
we lose the amplitude modulation
use transistors with lower voltage
it is solveable
73 DE muhsin TA1MHS

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Skipping past "no one will ever hear the difference at the other end"

You could certainly build a more powerful power amp stage into the QMX circuit.? ?You might find yourself upgrading other components (LPF's, TX RX switching etc).? ?From my experience the 10W linear is not flat gain over the full HF bands so programable or frequency contoured attenuation might still be needed and that might need a T501 /buffer/amp stage.? ?The power control part will certainly need re working and that's probably not as easy as it sounds

Overall I think you'd need to build the QMX board into the same box as a PA board and that would make it a lot less neat and tidy and considerably hotter so throw a fan in too.

So in short - just connect them together? NO
Just bridge the 10W pa board into the QMX plus PA stage space? ?Complicated
Remove the 10W PA's drivers and feed the QMX+ PA output there before returning to the switched LPF's Also complicated, still needs adjustable /contoured attenuating etc?

In short if you want to use the QMX+ and 10W PA circuits /boards as the source / inspiration for a quite complicated project and have the necessary knowledge and test gear it is possible to build a 'QMX+10W'? ?However if you have the necessary knowledge and test gear you probably wouldn't need to ask? . .?

Lets end with "no one will ever hear the difference at the other end"

I plan on using the QDX with the 10 w amp. QDX built for 12 volts and supplied with just 6 volts then output fed through a 20 dB attenuator. Will use PTT to bypass the attenuator and the amplifier on receive.

Schreibel,

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How do you plan to address the low pass filter requirement?

Crazy but Good luck . .? ?

IC2 regulator to name just one will not be happy at 6V and hope you know you'll need a load of band switched Low pass filters on the 10W amp output too.

Hi Alan,

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Yeah I saw that. I deleted the post shortly posting it. Not sure why anyone’s still seeing it.

Thanks for that heads up. I need to do a better job of researching my curiosity before asking the group.

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Don.

Only going to use it on 17.

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You apparently do not understand how things work.

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--

Allison
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Post online only,?
direct email will go to a bit bucket.

Ta1mHS

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The 10W amp was designed for lower drive levels.? For a QMX to do that

and not sacrifice anything There is a need need to attenuate its output

by roughly 20db.? To me a waste of power.

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Since the 10W amp is only that all of the switching for RX and TX needs to

be created and that would also include low pass filter.

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Generally using that amp at the output of a radio that does

3-5W is barking up the wrong tree.? IT also does not increase the

power enough to be significant (20W wold be a marginal increse)..

?

--

Allison
------------------
Post online only,?
direct email will go to a bit bucket.

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On Thu, Feb 27, 2025 at 08:57 AM, ajparent1/kb1gmx wrote:

Generally using that amp at the output of a radio that does

3-5W is barking up the wrong tree.? IT also does not increase the

power enough to be significant (20W wold be a marginal increse)..

?