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I built my QMX for 9 volts.
After the L401 jumper mod I kept the original number of turns and spread them out as much as possible.?
The receive has improved but the transmit power is well below what the manual shows it should be.?
80M 4.0W 60M 4.1W not to bad but 40M 2.6W 30M 3.3W 20M 1.9W.?
I've recounted all the wrap counts on the transforms all for good. I've rechecked all soldier connections.
I also checked to be sure 20M pin was set to 30.?
Has anybody else having this problem???
I know there is a lot of firmware upgrades in the future but don't know if any of these issues are firmware related.

My test equipment is a old Fluke DVM.
Looking for thoughts and ideas.

TIA?
Larry NA0F

Hi Larry,

Please review the following video.? It is for the QCX+, not the QMX.? The principle applies.? You what to try adjusting the LPF inductors to see if you can optimize the power out:


There is no class E amp in the QDX (the QDX is class D), so ignore the first part on adjusting L3.? The QMX uses 5 pole filters, so only two inductors can be adjusted.? The other point is that the LPF is shared for one or more bands.? You may have to choose between bands or find the middle power output.? The example is 20 and 30 Meters share the same LPF.? You can optimize for 20 or 30 or find the midpoint between the two.

73
Evan
AC9TU

On Fri, Jul 14, 2023 at 11:31 PM, Evan Hand wrote:

You can optimize for 20 or 30 or find the midpoint between the two.

I have found that when doing this type of tuning it helps to make up a chart of power and current by band, then try a tuning change and plot how the various parameters change with up, down or neutral arrows.??
It soon becomes apparent which changes are helpful and which are not and gives you a hint on how to balance them.? Harder to describe than to do.?
Paul Wade, now W1GHZ, taught me this at my first job at MSC, in the '70s and it has served me well.
73, N2VGU.