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40 m QCX on the air with an interesting enclosure.

 

Hello to the group,

My 40 m QCX is on the air. The only issue was the need to add the Schottky diode between pins 7 and 20 of the processor as it refused to start.
I modified the center frequency to 480 Hz, and I am waiting for the firmware upgrade to enable the CW decoder on that AF frequency.
This QRP transceiver is impressive, very sensitive, strong rejection of the unwanted sideband, and 4 W out with 12 V supply.
Having built many kits (HW7, HW8, HW9, Sierra, Norcal 40, K1, K2, K3, KX1...) I am very impressed by the quality of the manual and I measure the huge work it needed, so congratulations for this outstanding job.

I used a commercial low cost enclosure to house the QCX : https://www.gotronic.fr/art-boitier-beige-g738-6630.htm
The enclosure doesn't need any modification.
About the QCX, the 7805 regulator must be soldered 3 mm lower than the display.
The power supply terminal can be conserved, but you need to solder it with the connexions toward the display.
The gain and encoder axes were extended.
2 push buttons are added to control menus.
A DC socket, micro fuse and switch are added.
Finally a key from QRP Guys was fitted on the enclosure.

You can see pictures :?/g/QRPLabs/album?id=12705

Best regards

Georges F6DFZ
 

Nice Job

-------- Original Message --------
Subject: [QRPLabs] 40 m QCX on the air with an interesting enclosure.
From: f6dfz@...
Date: Thu, December 14, 2017 11:58 am
To: [email protected]

Hello to the group,

My 40 m QCX is on the air. The only issue was the need to add the Schottky diode between pins 7 and 20 of the processor as it refused to start.
I modified the center frequency to 480 Hz, and I am waiting for the firmware upgrade to enable the CW decoder on that AF frequency.
This QRP transceiver is impressive, very sensitive, strong rejection of the unwanted sideband, and 4 W out with 12 V supply.
Having built many kits (HW7, HW8, HW9, Sierra, Norcal 40, K1, K2, K3, KX1...) I am very impressed by the quality of the manual and I measure the huge work it needed, so congratulations for this outstanding job.

I used a commercial low cost enclosure to house the QCX :
The enclosure doesn't need any modification.
About the QCX, the 7805 regulator must be soldered 3 mm lower than the display.
The power supply terminal can be conserved, but you need to solder it with the connexions toward the display.
The gain and encoder axes were extended.
2 push buttons are added to control menus.
A DC socket, micro fuse and switch are added.
Finally a key from QRP Guys was fitted on the enclosure.

You can see pictures :?/g/QRPLabs/album?id=12705

Best regards

Georges F6DFZ
 

Great minds think alike!? I also used the same Velleman G738 enclosure for my QCX.? Inexpensive and easy to work with.? I will post mine next week when I am off work.?

73/72,
Dean K5DH
20m QCX msn 612
 

A very clean installation!? Nice work!??

73,
Kent
W9WB
[email protected]
 

Concerning "I modified the center frequency to 480 Hz, and I am waiting for the firmware upgrade to enable the CW decoder on that AF frequency", what is the frequency of operation of the decoder restriction?? I wanted to move my offset to 600Hz from the stock 700hz, but will rethink that if it means giving up this feature. Is that too far way from 700 to operate properly?

Bill
W2EB
 

Hi Bill,

As far as I know, the decoder central frequency is 700 Hz. The filter bandwidth is about 200 Hz, so it will certainly work.
Hans plans a firmware update with the choice of different central frequencies for the decoder, and I believe 600 Hz will be one of these.

Best regards .

Georges F6DFZ?
 

hi Georges!
what value of the menu items 3.8, 4.8, 8.2, 8.3, 8.4 you installed for 480 Hz?
 

Hi Andy

Here are my values :

  • 3.8 480
  • 4.8 480
  • 8.2 480
  • 8.3 430
  • 8.4 530

For 8.3 and 8.4, I first tried 380 and 580, but the LO value gave no definite null. With these values, LO and Hi null are well defined.
I checked with my HP signal generator the opposite sideband, and I believe there is over 40 dB of rejection as, even with ear splitting signal on the selected sideband (-47 dBm !) I couldn't detect the opposite sideband.

Perhaps Hans could confirm if these values for 8.3 and 8.4 are correct for a 480 Hz central frequency.

Best regards

Georges F6DFZ
 

Hi Georges

I expect with 380 and 580, the "Low" was out of the range of adjustment of the trimmer. Your values sound reasonable to me. But I have not had time to extensively investigate lowering the center frequency.?

I added your values and comments to the mods page? so that it is useful to other readers.

73 Hans G0UPL
?

On Fri, Dec 15, 2017 at 9:30 PM, <f6dfz@...> wrote:
Hi Andy

Here are my values :

  • 3.8 480
  • 4.8 480
  • 8.2 480
  • 8.3 430
  • 8.4 530

For 8.3 and 8.4, I first tried 380 and 580, but the LO value gave no definite null. With these values, LO and Hi null are well defined.
I checked with my HP signal generator the opposite sideband, and I believe there is over 40 dB of rejection as, even with ear splitting signal on the selected sideband (-47 dBm !) I couldn't detect the opposite sideband.

Perhaps Hans could confirm if these values for 8.3 and 8.4 are correct for a 480 Hz central frequency.

Best regards

Georges F6DFZ
 

Hello, Georges
thanks for the info.?
I'm still waiting for my kit to start assembling.
but definitely, the tone of 700 Hz (by default) is very uncomfortable for me.
I usually use a tone of 450-550 Hz maximum.?
best regards from RW9RN!
 

Hi Hans,

Thanks for sharing my comments, and again congratulations for an outstanding rig and a perfect manual, at an incredible price.

Can you confirm if the firmware update with choice of different center frequencies for the CW decoder is still in the pipe ?

Happy Christmas, new 2018 and best regards .

Georges F6DFZ?
 

Nice build! ?I think my next build is gonna be in a slightly larger case like that to give me more room for connectors and the like.
 

Please tell me what to choose? ?The resistors for 480Hz or the original resistors the will work for the 700Hz cw tone. ?I am in a stage that I am ready to install the resistors, ?and I wish to select what is best for the performance of my 20m qcx

Dany Sadan?
4X1MJ
 

I am in a stage that I am ready to install the resistors, ?and I wish to select what is best for the performance of my 20m qcx
Dany,
This is your choice. You have to decide what tone you prefer.

73 Alan G4ZFQ

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