Re: QCX 40 meter build help, 700 HZ tone shows up in weird place... #40m #si5351a


James Daldry W4JED
 

Hi, Mark

I would start by taking a fine solder pencil tip and reflowing the connections on IC1. It wouldn't be the first time I saw a leg on an SMD chip hanging a couple of thou above the foil, making like a tiny microswitch CW key.

73

Jim W4JED

On 6/5/20 10:50 PM, n8iaj via groups.io wrote:

Hi everyone!

      Thank you for the add.  I'm really excited about building my 40 meter QCX I ordered.  Got a problem that is perplexing me and I want to pose to the group.

I'm troubleshooting on why I do not have a 700 hz tone when I go to 8.7 BPF Alignment.  So I'm using a cheap DSO 150 scope and start tracing as by Han's troubleshooting video.  
Here is the weird part, Start 8.7 BPF alignment, plug in headphones,  I start at the source for the tone output, IC1 pin 6, I touch it with the probe - Tone comes on through earphones and my display jumps up to 10 and allows me to peak it at 11.  I remove the probe from the pin, it all stops and my display goes down to 3, no audio.

Has anyone out here come across this?  Of course, I've checked my solder joints and values of components.  All my IC's show correct voltages but no 700 hz tone on the pins.

I sincerely ask for any suggestions and thoughts on what I can do.  I know I'm so close to getting this on the air. Not to mention the cabinet I've been building for it.

Thanks for reading.

Mark

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