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For normal CW use, the QCX is usually safe to operate at 14v or so. Standard bench supply of 13.8 is perfect. If you are using the WSPR feature though, you should reduce the voltage to get the power

You beat me to it, I was about to edit my post on the all-pass/Phase rotator. Here is a primer and I have this board in my audio chain for my main rig. I went to TI.com and modeled a really simple one

Hello again Ron Further update on this. I now think that though I agreed with you, both you and I were wrong. Changed my mind. I do believe it's exercising the '5351 modulation as well as amplitude

Dan, good description of the symptoms. I think you have an intermittent connection, probably an old solder joint that was good enough early on but has degenerated over time. Specifically it is

What is the recommended voltage for an early QCX ver 1? I haven’t used it much but have been using a 8 AA battery pack 73 John N4HNO

I don't think there is any reason why not, all you need to do is change the LPF and BPF toroids, windings, and their associated capacitors. Maybe also do T501 using the RWTST method. Chris, G5CTH

Excellent!? Well done. Peter GM0EUL

Steve: The amplifier connects to the headphone jack.? On the Jack there are switched outputs that connect to the QMX's internal headphone amplifier, these switched outputs disconnect when headphones

Hi Damon A what??? 73 Hans G0UPL http://qrp-labs.com https://buymeacoffee.com/g0upl wrote:

Quick question: I have an unbuilt rev 1 QMX board. Assuming I change the LPF toroid windings, is there any reason that a Rev 1 board can't be built for 20 - 10 meters? Thanks. Mitch NK3H

I should also mention that I'm able to change the frequency with the encoder when my issue occurs.

Hello - Curious issue with my 20 meter QCX Mini. On power-up, everything works fine. After a few minutes I can't adjust the tuning rate with the encoder and the two buttons are non-functional. Turn

After becoming an expert in the fine art of BS-170 replacement, I finally discovered that the real culprit wasn't the transistors—it was a so-called "12V regulated power supply" that was as

Hello Anders Yes, this is what I was thinking. But if there are other meanings of binaural that people want, I would consider adding more options. 73 Hans

No idea. Have you checked all of the soldering in the L401 region?

Hello! Does this mean I need to replace IC402?

Hi Hans and list. Binaural can mean many things. One meaning is to have different CW filter center frequencies in the different ears, so that the signal of interest sounds like it is in the middle,

Dave, you may check Plug-in PCB#2 offline using QMX QMX_Plus Power supply test Process ( /g/QRPLabs/wiki/37128 ) from the QRP Labs Wiki. At the end of the text you find the methode to

Dave, sorry I made a mistake. In the current situation VDD for the mainboard is produced by the linear regulator and should be around 3.0 V (see VDD pin on mainboard). VDD from the SMPS exists only on

According to the WSJT-X manual in section "5. Transceiver Setup" AGC should be turned off: " Use the receiver gain controls and/or the computer’s audio mixer controls to set the background noise