Scott, 12 O'clock is great--right in the middle of the adjustable range. John / AC2SG

#40m #bpf #alignment #qcxmini

Grazie! Cheers Scott

#40m #bpf #alignment #qcxmini

Mine peaks around 8 very close to full capacitance. I left it and it works fine. I would leave it and see if everything else works well. If it does, I’d say leave it.

#40m #bpf #alignment #qcxmini

Completed my QCX-mini build and onto peaking the BPF. [Question] I'm able to peak the BPF a good 8; however, when I check C1 as per the assembly manual, the solder blob is literally at the 12O'Clock p

#40m #bpf #alignment #qcxmini

Laszio Very good suggestion. I recently built an COSMAC 1802 system and did the same. Installed, power connector, IC sockets and bypass caps. Powered on and checked for proper VCC on all ICs and of co

#40m #alignment #bpf

Hi Peter, all Yes, PCB trace errors do occur sometimes. Not often, but they do. Checking supply voltage to all the chips is a good idea. And following that the rest of the troubleshooting guides norma

#40m #alignment #bpf

Although I'm very impressed by the quality of the PCBs supplied by Hans - especially the silk screen printing, I too had a slight problem, but with the 50W amp board. The trace connecting the two seco

#40m #alignment #bpf

You're absolutely right Jim, pin 8 the power pin, on both chips. That's why it was the last pin I had on my list. Too much looking at the board from the bottom, I guess.

#40m #alignment #bpf

Um, excuse me, Laszlo Don't you mean pin 8 of IC5? Pin 1 is the "a" half output. Jim W4JED

#40m #alignment #bpf

I just had an interesting couple of days tracking down a problem with my QCX+. The general symptoms were no BPF peak, low headphone volume during BPF peaking and very low values for the amplitude scal

#40m #alignment #bpf

So, that about wraps it up :-) Glad to hear you got it nailed down! Having some WW wire is a big help repairing traces! I've got a spool of it left over from a project I built for my son, close to 30

#bpf #problem #si5351a #t1 #40m

Hey Al, Thanks for the help but it turns out that it was a board fab problem. The circuit board, as supplied by QRP Labs had a faulty trace from +12v to pin 1 of IC5. The resistance between the pin 1

#bpf #problem #si5351a #t1 #40m

I'll take a shot now that the 'scope and and clock frequency are sorted out. Plenty of signal at IC3 pin 10, are you getting the same 4.8V p-p at pin 8 of IC3? Only 15mV p-p at BNC center pin. Seems l

#bpf #problem #si5351a #t1 #40m

No change with the headphones unplugged.

#bpf #problem #si5351a #t1 #40m

Hello other Alan, you replied while I was replying to Alan G4ZFQ. As you can see in that reply, I found the source of the spurious frequency error indication and have already resolved to use the dummy

#bpf #problem #si5351a #t1 #40m

I agree, it should be completely impossible, hence my post. And you were dead on blaming the scope, too. I found dirt on the sweep rate selector switch contact and cleaned it off. Now it's showing a t

#bpf #problem #si5351a #t1 #40m

I would question you really have the Si5351 running at X3 Remember it's output is a square wave, because of it's rapid state changes it's rich in harmonics Short & good Grounding of the test prods and

#bpf #problem #si5351a #t1 #40m

Try the alignment again without anything connected to the headphone jack. I don't think the QCX is capable of driving a Sony studio grade headset from 20 years ago

#bpf #problem #si5351a #t1 #40m

This does not seem possible. Is there any chance of your scope being wrong? It is nothing like the same but sometimes my frequency counter shows 3x the correct frequency. Can you confirm this with som

#bpf #problem #si5351a #t1 #40m

Started aligning my 40m kit. Factory reset, set 40m band. Firmware is 1.06, no TCXO. BPF peak was weird, Volume was very comfortable through headphones on my head, rather than the earsplitting howl we

#bpf #problem #si5351a #t1 #40m