Re: QCX+ 30 build problems help please

John Pagett G4YTJ

Hi Les,

When I said to listen for the TCXO, I meant to say to use a general coverage receiver tuned to 25MHz. Sadly I didn’t make that clear.

If you want to do it now then you need to set the receiver to 27MHz (probably a few kHz up in practice)

Now that you’ve swapped back to the crystal you have to set the reference frequency in the set up menu back to 27.004 MHz. (27.004 is the default value that Hans uses as a “first guess” . This is 8.5 in the menu system, though the factory reset may already have done that for you.

I have had an instance with one of my QCXs where there was a lot of hum, this was down to the power supply I was using.

Does the hum level vary with volume control setting?
If the hum is 50Hz or harmonics it might be an open circuit somewhere. On the QCX+ the volume control is on the front panel and the connectors between that and the main board could be a potential fault area.

If the hum is not 50Hz or harmonics then it could be a stage oscillating. Low impedance phones can trigger that but if your phones are ok on the working rig then that’s unlikely.

Sorry if this isn’t much help but fault finding at a distance is quite difficult!

I see you overtook me in the ladder - well done.


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