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K3KDW,

You want to measure the resistance on the bottom of the mainboard with the power supplies removed.? Attached is a PDF with the pin locations.

73
Evan
AC9TU

Thanks for the reply! Could you guide me on where to test?

Same here.

I ended up finding a seller on Amazon a few weeks ago and grabbed one.

Todd K4MSW

I agree, my Motorola Service Monitor has a TO-3 zener diode on a huge heat sink protecting its 5 volt supply. Gotta love brute force.

I accidentally fed 26v to my QMX. That's what I get for keeping too many running projects laying around, especially when they require wildly different voltages but the same plug format. Next time I'll tag the only correct supply.

Am I probably safe once the SMPS boards are replaced or is there a good chance for more damage?

First time installment of a firmware on a new QMX (no EEPROM file) will not initalize all menu settings correctly. In the menu the keyer setting defaults to straight and tip.
Change it to to e.g. iambic a and ring and leave the menu. Then reenter the menu and revert the keyer setting back to straight and tip.
HTH Gottfried

If you're interested in ordering the?VIFLY ShortSaver you might as well order them directly from China via AliExpress and save some money. I ordered some from?VIFLY Drone thinking that I was helping a small business and would get them in a timely manner. Well after a week I finally got an order confirmation and that they were being shipped from China. A couple more weeks have passed and I still haven't gotten them. They have at least gotten through customs!

Roy
WA0YMH?

Oh, yes, that was a nice trick.? I figured out the problem with 15m is that the cutoff frequency is too low, and 21.074 MHz is actually more than 3dB down.? I did the transmitter test at 19MHz, well inside the passband, and got 4W.? So I need to tweak the toroid to push the cutoff frequency up.? The same might also be true, to a lesser extent, on 12m and 10m.

Eric

I accidentally plugged in a 26v supply from another ongoing project. Do you suspect I'm ok after replacing the SMPS boards or is this disaster likely more serious?

On Tue, Feb 27, 2024 at 08:20 AM, @Ludwig_DH8WN wrote:

Please be aware of the different stray capacitance and the capacity of the connected QDX circuits. And use a rf suitable board!!!

My final result of my whole testing was: Following the manual brings good results or at least a good start point to tweak the filters.

Thank you for your thoughts and clarifications!

The more I play in Elsie with LPF simulations, the more I agree that following the manual will be a good start. It seems in the QDX HB, the 15/17m LPF is the most sensitive to the inductance values. The others are more...robust. Especially as far as reflected power to the PA. And there are more downsides to using less turns on the 15/17 than the recommended number of turns, even if inductance is higher than spec'd/calculated. So I will follow the manual pretty closely, maybe doing 20T instead of 21 on L2, but that's the only change.?

-Nate?
N8BTR

On 27/02/2024 15:45, jh4vaj wrote:

t appears that the values of C516 and C525 are swapped between the schematic and the manual.

"The current assembly manual is correct: C525 is 270pF and C516 is 180pF. "

Be careful, simulations must account for stray capacitances.

73 Alan G4ZFQ

You can adjust input gain in the terminal configuration menus.
73
--
David Thomas M0OOR

?? I agree!
--
?

73, Barb

I have used numerous ProgRock2's without any problems -- I install them in old receivers and transmitters to replace faulty/drifted crystal-based heterodyne oscillators.? What are you trying to do and what went wrong?? Possibly I can help.

73 - Steve, KW4H

Did you made the output transformer in the WSTS style?

73, Ludwig