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Hello,
Relatively new to this group and building QCXs… so, please bear with me.
Just finished building the QCX-mini (25mhz TCXO + AGC modules added as well).

?Failed first two attempts to align. ?Display only read intro and then garbled display results accompanied by high pitch buzzing (that could have my brain sizzling). ?

Cleaned up ?boards, re-heated solder points, looked over all boards with jelwer’s loupe and on the third attempt, I finally got into the menu. Could not identify any single “event, that was obvious anyway. ?

Currently - buzzing still present until I access menu. I can access 8.0 Alignment, ?and all sub-menus. ?

What I cannot do is get IQ R27or High R17 to drop on to minimum reading as they should - even after multiple turns of each. ?And BPF C31 is peaking as it should on adjustment either - only budges up bit.

So,my questions for this group: ?is the buzzing a fried set of finals (good at frying steak, maybe finals too); and; is the lack of co-operation from adjusting the phases a result of poor workmanship on T1 - does it need to be re-wound ?by a more experienced me?

Help please and thanks …
Cheers
Dan. VE7CTN

Dan

things may be okay. It’s easy to jump to false conclusions. The capacitor peaking usually isn’t sharp, finding where it increases output tends to be good enough. Now for the nulling operation carefully read instructions. There are 3 pots and each uses a different menu setting. They interact a bunch and initially each by itself doesn’t null easily. But when all 3 are near a null the magic happens. Also note the display starts to reach its null, then it rescales and it’s back to peaking a bit. Watch as you see the index number on the display decreases by one each time. This is all way cool and very effective.?

on one build I had one control not working. It’s pot wasn’t properly soldered, the pins are a bit smaller than the hole. So check this if you have a non responsive pot.?

especially 20m and higher easily to visually see that coil hopefully matches picture, lower bands just more study. Of course each needs a good solder connection.?

curt

Hello N3NMT, and thanks for your reply.
Yes, I did.

Set the freq to 25 MHz. ?Adjusted alignment freq to 14.020 mhz (20 m model). Using an iPhone ear bud (impedance should be about 32 ohms). ?50 ohm Drake dummy load attached. ?

Now, the volume level is something to play with and I’ll try that next go around . ?Thanks for the hint.?

Pins on the uC are not bent, seated well as I straightened and aligned them all prior to installing - and re-seated and inspected twice. So, it’s ok.

Also using a CW Morse ?mini paddle with a stereo connector - as it should be , I think.?

Thanks for the reply Curt.

Your experience and advice here is invaluable - because maybe I’m expecting a more dramatic “dip” or “peak” than I’m seeing. ? And, yes, I’m aware of the separate menus for each adjustment.?

I know it’s transmitting. ?Even with the QCX xmitting into a dummy load I can hear a signal on my IC-705. ?I’ll have to dig out an old OHR QRP watt meter to see how much power, but didn’t want to xmit until I was convinced it was safe … maybe that time won’t come, just leap and look later.?

Thanks again Curt

Well, after following advice from Curt and N3MNT, the QCX-mini is working.
Output was only about 2.8 Watts, but video by ?Hans on tuning set it all straight. The 20 m version often requires removing 2 turns from L3 in the band pass network. ?Removed 1 turn, power increased to another 3.8 watts output ? Removed second turn and power output went to full 5.2 watts output with 13.8 volts power supply.
Now, back to the receiver and I am sure it will be “as advertised”.
Really looking forward to using this little radio in the field - everything I’ve seen or read about it is extremely positive.?
Thanks again guys for your help
Cheers
Dan VE7CTN