Topics

#qcx #video tuning up your QCX, power output and receiver adjustment #qcx #video


Hans Summers
 

Hi all

Last night while testing and adjusting a small pile of assembled QCX+ radios that we sell in the shop http://shop.qrp-labs.com/assembled , I had an idea to film the process for one of them, so that it may help some constructors who have difficulties. Particularly, low power output seems to be a question which comes up from time to time. 

The particular example unit which I chose for the video, which was simply the next in line on my pile, was a QCX+ 30m with TCXO option and enclosure option installed. The video takes you through in some detail, the procedure I go through to test and align the radio; including to start with, the output power.  


To start with, the power output as assembled was only 0.77W (with 12V supply). In the end I measured 4.6W at 12V (and with 13.8V supply, 6.4W). I also checked the spectrum analyzer after the tune-up and measured -54dBc 2nd harmonic and -66dBc third harmonic, with all higher harmonics disappearing into the noise floor. Just to show the LPF tune-up didn't do anything bad to the spectral purity :-)  

This video also goes through the receiver alignment procedure: BPF peaking, I-Q baland and phase adjustments; and finally calibration of the system and PLL reference oscillator using a QLG1 GPS. 

73 Hans G0UPL
http://qrp-labs.com


morseoneuk
 

Great video Hans,    most educational,  all becomes clear.   
Scotty


Al Holt
 

Hello Hans, great video!!

It's good to see, I'm like you with a (natural?) tendency to grab the VOL control when I really want to adjust the TUNE control. Hi-hi!

Your method of adjusting Hi and Lo Phase cancellation before I/Q balance is slightly different from the manual. This approach, plus your description in the video, makes sense and clears up the procedure for me!

Congratulations on the presentation!!

--Al


W5EGA@...
 

Thank you Hans! This was a very informative video.

73, John W5EGA 


The Crunchbird
 

Great video, well done. Dave. N2SN


geoff M0ORE
 

Good video, was it filmed via a mirror or do I have a problem with my PC?

On 23/09/2020 13:38, Hans Summers wrote:
Hi all

Last night while testing and adjusting a small pile of assembled QCX+ radios that we sell in the shop http://shop.qrp-labs.com/assembled , I had an idea to film the process for one of them, so that it may help some constructors who have difficulties. Particularly, low power output seems to be a question which comes up from time to time. 

The particular example unit which I chose for the video, which was simply the next in line on my pile, was a QCX+ 30m with TCXO option and enclosure option installed. The video takes you through in some detail, the procedure I go through to test and align the radio; including to start with, the output power.  


To start with, the power output as assembled was only 0.77W (with 12V supply). In the end I measured 4.6W at 12V (and with 13.8V supply, 6.4W). I also checked the spectrum analyzer after the tune-up and measured -54dBc 2nd harmonic and -66dBc third harmonic, with all higher harmonics disappearing into the noise floor. Just to show the LPF tune-up didn't do anything bad to the spectral purity :-)  

This video also goes through the receiver alignment procedure: BPF peaking, I-Q baland and phase adjustments; and finally calibration of the system and PLL reference oscillator using a QLG1 GPS. 

73 Hans G0UPL
http://qrp-labs.com


Shirley Dulcey KE1L
 

Only some of the scenes are mirrored. Those were probably shot with the selfie camera on his phone.


On Wed, Sep 23, 2020 at 6:41 PM geoff M0ORE via groups.io <m0ore=tiscali.co.uk@groups.io> wrote:

Good video, was it filmed via a mirror or do I have a problem with my PC?

On 23/09/2020 13:38, Hans Summers wrote:
Hi all

Last night while testing and adjusting a small pile of assembled QCX+ radios that we sell in the shop http://shop.qrp-labs.com/assembled , I had an idea to film the process for one of them, so that it may help some constructors who have difficulties. Particularly, low power output seems to be a question which comes up from time to time. 

The particular example unit which I chose for the video, which was simply the next in line on my pile, was a QCX+ 30m with TCXO option and enclosure option installed. The video takes you through in some detail, the procedure I go through to test and align the radio; including to start with, the output power.  


To start with, the power output as assembled was only 0.77W (with 12V supply). In the end I measured 4.6W at 12V (and with 13.8V supply, 6.4W). I also checked the spectrum analyzer after the tune-up and measured -54dBc 2nd harmonic and -66dBc third harmonic, with all higher harmonics disappearing into the noise floor. Just to show the LPF tune-up didn't do anything bad to the spectral purity :-)  

This video also goes through the receiver alignment procedure: BPF peaking, I-Q baland and phase adjustments; and finally calibration of the system and PLL reference oscillator using a QLG1 GPS. 

73 Hans G0UPL
http://qrp-labs.com


Hans Summers
 


The entire video was shot in single take, unprepared, unscripted segments, all using my phone. Some using the front camera, some using the selfish camera. The selfie camera mirrors. The scenes were put together using the "YouCut" app and trimmed where needed. I tried to remember to click the "Flip" button to re-mirror the selfie-camera scenes or should that be de-mirror or un-mirror. But one or two I forgot. I mean, just checking to make sure you're paying attention, Geoff ;-)

73 Hans G0UPL 

On Thu, Sep 24, 2020, 01:53 Shirley Dulcey KE1L <mark@...> wrote:
Only some of the scenes are mirrored. Those were probably shot with the selfie camera on his phone.

On Wed, Sep 23, 2020 at 6:41 PM geoff M0ORE via groups.io <m0ore=tiscali.co.uk@groups.io> wrote:

Good video, was it filmed via a mirror or do I have a problem with my PC?

On 23/09/2020 13:38, Hans Summers wrote:
Hi all

Last night while testing and adjusting a small pile of assembled QCX+ radios that we sell in the shop http://shop.qrp-labs.com/assembled , I had an idea to film the process for one of them, so that it may help some constructors who have difficulties. Particularly, low power output seems to be a question which comes up from time to time. 

The particular example unit which I chose for the video, which was simply the next in line on my pile, was a QCX+ 30m with TCXO option and enclosure option installed. The video takes you through in some detail, the procedure I go through to test and align the radio; including to start with, the output power.  


To start with, the power output as assembled was only 0.77W (with 12V supply). In the end I measured 4.6W at 12V (and with 13.8V supply, 6.4W). I also checked the spectrum analyzer after the tune-up and measured -54dBc 2nd harmonic and -66dBc third harmonic, with all higher harmonics disappearing into the noise floor. Just to show the LPF tune-up didn't do anything bad to the spectral purity :-)  

This video also goes through the receiver alignment procedure: BPF peaking, I-Q baland and phase adjustments; and finally calibration of the system and PLL reference oscillator using a QLG1 GPS. 

73 Hans G0UPL
http://qrp-labs.com


Andrew Lenton
 

Nice one Hans

BR Andrew G8UUG


geoff M0ORE
 

I didn't know that the selfie camera gives a mirror image. I have never used a selfie camera and no wish to do so.

Geoff



Hans Summers
 

Selfie cameras are useful for taking a video of yourself rambling on about some radio topic or another. Selfie cameras give mirror images. WHY do selfie cameras give mirror images, who knows...
73 Hans G0UPL
http://qrp-labs.com

On Thu, Sep 24, 2020 at 12:14 PM geoff M0ORE via groups.io <m0ore=tiscali.co.uk@groups.io> wrote:

I didn't know that the selfie camera gives a mirror image. I have never used a selfie camera and no wish to do so.

Geoff



Giuseppe Marullo
 

WHY do selfie cameras give mirror images, who knows...
C'mon...to apply mascara to the intended eye, simple!

Try without the mirror function.


Brian George
 

A very useful video Hans. Thanks for going to the trouble of making it. My own tinkering suggests that the low power issue on 20m / 30m is more about P.A. stage matching rather than the LPF cut-off point. Your good results achieved only by removing turns on L3 would tentatively confirm this. I will adopt your procedure as the preferred approach in future rather than removing turns from all three toroids. This is useful info as I am currently building the QRPLabs  five band relay-switched LPF and have the same issue on 20m / 30m. 

The excellent spectrum analyser trace in your video was particularly reassuring.

73
Brian
G3ZOH


Ben Bangerter, K0IKR
 

Hans,

A very informative video indeed!  It would be interesting to lift C29 where it connects to C30 etc, and use a VNA (vector network analyzer) to see what sort of impedance a 50 ohm dummy load seen through the modified LPF presents to the class E amplifier output.

73, Ben K0IKR


Jim Painter
 

Great video Hans. As you were soldering, I found myself trying to blow away the smoke.

By expanding the turns on L3 of my QCX 20m, I increased power from 3 watts to slightly over 4 watts. I think I will leave well enough alone and not reduce turns.

Thanks Jim....kq3s


On Sep 23, 2020, at 8:38 AM, Hans Summers <hans.summers@...> wrote:


Hi all

Last night while testing and adjusting a small pile of assembled QCX+ radios that we sell in the shop http://shop.qrp-labs.com/assembled , I had an idea to film the process for one of them, so that it may help some constructors who have difficulties. Particularly, low power output seems to be a question which comes up from time to time. 

The particular example unit which I chose for the video, which was simply the next in line on my pile, was a QCX+ 30m with TCXO option and enclosure option installed. The video takes you through in some detail, the procedure I go through to test and align the radio; including to start with, the output power.  


To start with, the power output as assembled was only 0.77W (with 12V supply). In the end I measured 4.6W at 12V (and with 13.8V supply, 6.4W). I also checked the spectrum analyzer after the tune-up and measured -54dBc 2nd harmonic and -66dBc third harmonic, with all higher harmonics disappearing into the noise floor. Just to show the LPF tune-up didn't do anything bad to the spectral purity :-)  

This video also goes through the receiver alignment procedure: BPF peaking, I-Q baland and phase adjustments; and finally calibration of the system and PLL reference oscillator using a QLG1 GPS. 

73 Hans G0UPL
http://qrp-labs.com