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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

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?

Thank you very much for the information. Now I can proceed with the assembly with peace of mind.

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

http://qrp-labs.com/qmx/qmxtrouble.html "The current assembly manual is correct: C525 is 270pF and C516 is 180pF. " Be careful, simulations must account for stray capacitances. 73 Alan G4ZFQ

On the QMX rev.2 PCB, it appears that the values of C516 and C525 are swapped between the schematic and the manual. I have run simulations and the values in the schematic seem to be better. What do

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

?? I agree! -- 73, Barb

ROFL... and we can celebrate this fine Tuesday with one less mystery to worry about! 73 Hans G0UPL http://qrp-labs.com https://www.buymeacoffee.com/g0upl

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

Did you made the output transformer in the WSTS style? 73, Ludwig

Hi Nate From Material 17 I used the size 30 (T30-17). Validation by using T37-10 showed two things: 1. My setup brought probably to high values for L. 2. Despite the deviance (see No 1) the AL of the

You are right Hans! I forgot to mention the most important point! I lower voltage to 5V! Getting old!! Sorry for the snafu! -- 73, Barb

Hello Barb The maximum power dissipation of a BS170 according to the ON Semi datasheet (these are the devices we supply) is 0.83 Watts. If a QCX was producing 5W output at 60% efficiency the heat

Hans, I have QCX V1 and I adapted for usdx and used it with 1x BS170 without any problems many months. The PA efficiency is 60 to 70% which does not create significant excess heat. Actually that QCX

Wrongly wound SWR transformer? [email protected]> wrote:

Abbott & Costello did a great variation on it using "Susquehanna Hat Company" as the trigger phrase. https://www.youtube.com/watch?v=EJxLDdIVX6g

I've got a homebrew QRP power meter (photo of schematic) and it showed 17.7v (+3w) in my DVM.? That's quite a bit more than <.5w!? I'm gonna go back and reflow the toroids and transformers.? Maybe

Hi Barb No... all you do then is fry the BS170. The point of multiple BS170's is less about reducing the effective switch "on" resistance due to paralleling multiple devices. It's more to do with the

Barb, I wonder. I seem to remember that essentially the paralleled devices share the load. That has been mentioned with the U3S. Would just one be overloaded? In any case if the power was reduced to