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Yes, a 33uF electrolytic or tantalum capacitor will work, or probably even a ceramic. My first fix was to my QMX+, with a 22uF that I had laying around here. I just finished adding the fix to my QMX

Yes, the cap and diode are to give you a dc reading. Mike Krieger [email protected]> wrote:

Using two irons to heat both ends at once make this kind of task much simpler.? I have tried the tweezer type of iron but was unimpressed with its performance. 73, Don N2VGU

Your dummy load should have twenty resistors in place. I don’t think you should have extra resistors. If you have a meter, measure the resistance. You should see 50 ohms Mike

If you DO NOT read the instructions, you will wind up - upside down and everything will be back-asswards as it were.? You will then be tasked with " how the hell do I make this work since I have

Good to hear that all is OK (except for a lack of feet). Was concerned about your and your family's health. 73 Ron KA3PSO

Ian, this is pretty much what my plots look like. ?I am beginning to believe it is normal. Can you list your max power out on each band? ?That would give me a good idea of what I can expect after

[ Oops again.? I just deleted my prior 'one more note', since it was incorrect - I had confused my QMX and QMX+.? So here it is again, corrected. ] One more note: the dip you clearly see in my 40M

I have a REV2 and a REV4 QDX for sale. The REV2 blew the finals and a couple of parts came off of the pcb when the finals overheated. Repaired and used for a few months and then went dead. Do not know

Sorry, images from NanoVNA scan of QMX+ LPF attached.

I have done this LPF scan with my nanovna.? It is quite simple with the QMX+, if you happened to install your diodes with the cathode side up.? With the QMX you need to tack some wires on the diode

Steve Here are plots of LPF from 2 QMX+ and 1 QMX Hope they help 73 Ian G4GIR

What you have to do in so many circumstances to do with radio is read the instructions

Thanks again, Jerry! Manuel (DL2MAN) advises the same in his (tr)uSDX instructional video. He says, due to not being a 50 ohm system,? the LPF passband is not fully accurate from the nanoVNA, but

Oops--I forgot to clarify in my last post: Others are about -27dB at the 2nd harmonic or a little *more favorable*.

The LPF's on the QMX are not symmetrical. I would guess that T501 is driving into an impedance other than 50 ohms resistive, but close enough to 50 ohms that you would get meaningful plots from a

Thanks for your discussion of the VNA approach, Jerry! When I had to replace my SOIC gates after the finals in my QMX+ blew after experimenting with EEPROM settings in an ATU, I could not get the

I use a #15 scalpel blade and sever the leads at the body.? Hold the scalpel near vertical and use a rocking motion to shear the lead.? Pluck off the body then desolder the leads individually. 73,

Plotting QMX LPF's with a nanoVNA is not something I've done but: With the rig off, there should be zero volts across the 1n4007 diodes, isolating the LPF and making it possible to simply connect it

Personally, I do not use full auto tuning with a QRP Labs radio (or any other small, "hobbyist" QRP radio) at "full" power (4W even). I define "full" auto tuning as? the rig deciding when to tune. I