Date   

Is the 20m band quiet for CW or do I have a receiver problem with the QCX #qcx #rcvr

John KF6QPC <j.capel@...>
 

I've been having fun experimenting with the QCX as far as configuration and code practice.  However, after hooking up the QCX to an Elecraft T1 ATU and to a end-fed antenna, I'm not hearing any CW activity.  Is 20 meter CW activity dead at this time or do I have an issue with the receive section of the QCX?

BTW, I'm using the same antenna for FT8 and works well.

I look forward to any helpful suggestions.

73 John KF6QPC


Re: Unable to receive anything on my 20m #chat

gabri22_@...
 

Hi again,

I've just checked the resistance between wire ends of L1, L2, L3, L4  and T1 on the soldered pads below the PCB and I get 0 ohm readings :s . 

Thanks for your response Chopper.


Re: Unable to receive anything on my 20m #chat

N3MNT
 

Make sure you are making contact on the solder pads and not the wire ends when checking the connectivity of the T1 windings.  Readings that "jump around" when doing alignment is an symptom of poor solder connections on T1.  Use a ohm meter not audible tone.


Re: Unable to receive anything on my 20m #chat

gabri22_@...
 

Ok, so here you have the video example of the alignment process I performed. (Not too precise for having to hold the camer with the other hand, but you get the idea of the amplitude jump around and the values I get): https://www.youtube.com/watch?v=5lD0yGqcWmw

Thanks for the time you take to help me, I really appreciate it.


Re: Unable to receive anything on my 20m #chat

gabri22_@...
 

And yes, I tune my loop antenna and I am able to hear the increase in the background noise.

Thanks again, I am really lost with this because everything seems to be fine (at least in the receiving part). I will upload the video of the tuning process so that you can see how the amplitude bars jump around (which I assume it can be a problem for the receiving part)


Re: Unable to receive anything on my 20m #chat

gabri22_@...
 

Yes, I get the loud tone in the headphones and I've also checked the continuity across L1, L2, L3. However I did it only with the audible signal of continuity. Should I specifically check the resistance?
Thanks for your response.


Re: Dead on start up

Tim O'Rourke
 

Happy camper! I ordered 2 new inductors should be tomorrow. 
RX seems sensitive enough, can almost hear what the 7610 hears!
I ordered 2 new micros, seemed easier than doing it myself.
The audio does seem a bit on low side OK but could be louder for my 72 yr old ears.
Thanks everyone for suggestions that made this a quick fix.
BTW I was one of the first to sign up for kits at Friedrichstaufen in 2017, it was a treat to talk with chaps there about this great radio.
This will make a great portable rig and be used for demos at JOTA this year.
Tim W4YN


Re: Unable to receive anything on my 20m #chat

Rich
 

Good point - my post was poorly worded - they have a very narrow in-tune range for a given frequency.


Re: Unable to receive anything on my 20m #chat

jjpurdum
 

I think it's misleading to say they have a small tuning range. The range is fairly large, but the bandwidth without retuning is small. Indeed, many mag loops are multiband, but with less performance on some bands than others.

Jack, W8TEE

On Monday, September 17, 2018, 6:26:27 PM EDT, Rich <rich@...> wrote:


And - just in case you aren't aware, loop antennas have an extremely small tuning range.  You need to turn the antenna tuning knob slowly until you hear an increase in background noise.


Re: Unable to receive anything on my 20m #chat

Rich
 

And - just in case you aren't aware, loop antennas have an extremely small tuning range.  You need to turn the antenna tuning knob slowly until you hear an increase in background noise.


Re: Unable to receive anything on my 20m #chat

Rich
 

Did you get the loud tone in the headphones when aligning?  Have you checked that you have continuity (with an ohm meter) across L1, L2, and L3?


Re: QCX died after one QSO

Andy Kerrison
 

Well the blocks are back after an evening of running WSPR ok.

Switched it on tonight and blocks along the top again.

Reseated the micro-controller, no luck, re soldered the socket pins and still no luck.

I'll start checking voltages when I have more time.


Re: Dead on start up

Hans Summers
 

Hi all

The early L5/L6 did have some coating on the leads that made them difficult to solder, and also they were quite fragile. From a quite early batch we changed supplier to a better inductor, and I don't think these problems occur now. 

For replacement: the value is very non-critical, you don't need to be fussy about finding an exact replacement. 

73 Hans G0UPL

On Mon, Sep 17, 2018 at 8:01 PM Frank Waarsenburg <Frank@...> wrote:
Same here. L5 was replaced by another choke and that solved my startup problem. Serial 887. Looks like early L5s were causing problems sometimes.

72 Frank PA3CNO


Verstuurd vanaf mijn iPad

> Op 17 sep. 2018 om 18:08 heeft neil@... het volgende geschreven:
>
> Hi Tim,
>
> Interesting, I also took a long time to get round to my early kit (1.00b FW) and just had exactly the same problem.
> I tried shorting out the L5 (post pwrup modification) as suggested above and mine also sprang into life.
> Seems the modification is not always a complete solution.
>
> 73,
> Neil  G4BRK
>
>
>





Unable to receive anything on my 20m #chat

gabri22_@...
 

A new chat has been created:

Hi all, 

Months after I purchased the kit, I found some spare time to build it. I think everything went fine during the alignment process. I am able to find a maximum in the peak BPF menu and the plates of the trimmer capacitor are somewhere in their range.

However, I was unable to hear any station after several days and I am starting to think that there might be a problem.
Regarding this issue I wanted to ask whether it is possible to receive anything using this portable loop antenna: https://www.radioworld.co.uk/wonder-wand-wonder-loop-750-portable-loop-antenna

Do you think that could be the "problem"?  Or should I look for a hardware failure?

I do not know what can be wrong, the only thing I can think of is that during the alignment process, in the I-Q balance, Phase LO and Phase Hi menus, the amplitude bars jump around maybe too much (However, I can find a minimum value even though it does not remain "static")
I'll record a video of this so that you can actually see it if you think it is helpful.

This is my first transceiver ever, so I am a newbie in this topic and I feel a little bit overwhelmed about all the things that could be wrong. Maybe you can help me a little bit with your expertise on how should I proceed.

Regards,
Gabriel

View/Join This Chat


Re: Dead on start up

Frank Waarsenburg
 

Same here. L5 was replaced by another choke and that solved my startup problem. Serial 887. Looks like early L5s were causing problems sometimes.

72 Frank PA3CNO


Verstuurd vanaf mijn iPad

Op 17 sep. 2018 om 18:08 heeft neil@ignika.com het volgende geschreven:

Hi Tim,

Interesting, I also took a long time to get round to my early kit (1.00b FW) and just had exactly the same problem.
I tried shorting out the L5 (post pwrup modification) as suggested above and mine also sprang into life.
Seems the modification is not always a complete solution.

73,
Neil G4BRK



Re: Dead on start up

g4sra
 

The early L5's came with the leads coated with a substance that
interfered with soldering, forming a higher impedance joint of several
hundred ohms (DVM measurable by removing the ATMega).

The modification itself is sound.

On 17/09/2018 17:08, neil@ignika.com wrote:
Hi Tim,

Interesting, I also took a long time to get round to my early kit (1.00b FW) and just had exactly the same problem.
I tried shorting out the L5 (post pwrup modification) as suggested above and mine also sprang into life.
Seems the modification is not always a complete solution.

73,
Neil G4BRK


Re: Dead on start up

g4sra
 

I would remove the shorting link and replace L5 (which I found to be
very fragile) with something from the junk box directly between Pins 7
and 20. As it's purpose is to keep digital noise out of the analogue
circuitry, anything from 47uH to 270uH will do, it is not a critical
value component.

This 'Unreliable microcontroller start-up at power-on' modification is
documented on the website, refer to that and take whatever action you
feel appropriate.

https://qrp-labs.com/qcx/qcxmods.html


Re: Dead on start up

neil@...
 

Hi Tim,

Interesting, I also took a long time to get round to my early kit (1.00b FW) and just had exactly the same problem.
I tried shorting out the L5 (post pwrup modification) as suggested above and mine also sprang into life.
Seems the modification is not always a complete solution.

73,
Neil G4BRK


Re: Progrock, gps and receiver, gps pick up.

M0RON
 

Hi Alan, 
Touching the pins with a finger on the shaft of a screwdriver injects an ac hum. I had traced back to c9-11 and all good so it had to be a problem in the front end. 
Voltage on pins 7 and 9 of fst3253 were 2.5v, voltages on c3-6 were good. Good voltages on pins 10-13. Q1 and 2 both looked suspect with little voltage on some pins, Changed them and voltages came up quite a bit. 
My last kit from QRP Labs had a dud transistor and also 4 out of 5 7809's bought recently had 6.07v out, only one was 9v.
In future I think I'll check components as I fit them, no matter where they are from,  may take longer to build but it may avoid hours of trouble shooting. 
Thanks, 
Andy

Andy.


Re: Dead on start up

Tim O'Rourke
 

Shorting out L5 that was placed between Pins 7 and 20 did the trick 
Now both Micros start up
Do i put L5 back to original location ?
On to doing calibrations etc
Tim