CQ WPX CW 2021 with QCX+


cris blak
 

Hello All,

CQ WPX CW 2021 just ended and I'd like to share with you my experience.
I'm posting here due to the QCX+ uses in the contest.
At the fist look I thought it will not work to use QCX+ in such a big contest due to its simplicity but...I give it a try so...

Category was QRP 40m.
RIG QCX+ with 5W output through a home brew ATtunner (see pictures - was taken as it was used during the contest! - means with open case); just before the contest I thought it will be best to have a "still unfinished " AGC circuit so I build the "simple AGC" (from this forum) on a breadboard. Another "keeping" modification was the 5V regulator replacement with switching mode DC-DC converter (which does not bothering the RX at all).
ANT was INV.V  for 40m band on 30m high building.

On short, I made 613 QSOs with all continents (except Antarctica). This is a QRP personal record ever.

The sensitivity of the RX was more than enough hearing almost everything. The trouble was with the overload of the front end.
As I mention on my previous measurements (posted on this forum), a signal over about S9+25dB will overload the RX of the QCX. So it was not hard for many signals on this contest to do so! Those were very distorted but readable.
The good part was that about 300 400Hz away from the strong signal, the overload just vanished and the weak signals could be received.

Of course is not IC7300 with waterfall and spectrum scope but it was leading me to a good result I guess.

Cannot described the joy to use such a small piece of HW to work DX through pile-up!

You have to try it.

73 de YO3FFF
Cristi


Mel Snyder
 

Cristi, that is spectacular! It didn’t hurt that you have a desirable prefix and your antenna is at an enviable 30 meters. But 613 contacts on all continents on 40 meters with 5 watts is truly remarkable. Your observations. About your QCX+ are the same as mine: sensitivity and selectivity are exceptional. 

I wasn’t into the contest except for perhaps 3 hours (my only “contest” each year is about 8-10 hours on our “Filed Day". But I decided to do that with my “QRO” KX3 on 20 meters after first testing with my 40 meter QCX+ into my Butternut HV9V - and seeing how relatively easy it was to make contacts at 5 watts.

You’ve likely won the QRP division for YO!

Mel, W3PYF

,

On May 31, 2021, at 4:11 AM, cris blak via groups.io <cyo3fff@...> wrote:

Hello All,

CQ WPX CW 2021 just ended and I'd like to share with you my experience.
I'm posting here due to the QCX+ uses in the contest.
At the fist look I thought it will not work to use QCX+ in such a big contest due to its simplicity but...I give it a try so...

Category was QRP 40m.
RIG QCX+ with 5W output through a home brew ATtunner (see pictures - was taken as it was used during the contest! - means with open case); just before the contest I thought it will be best to have a "still unfinished " AGC circuit so I build the "simple AGC" (from this forum) on a breadboard. Another "keeping" modification was the 5V regulator replacement with switching mode DC-DC converter (which does not bothering the RX at all).
ANT was INV.V  for 40m band on 30m high building.

On short, I made 613 QSOs with all continents (except Antarctica). This is a QRP personal record ever.

The sensitivity of the RX was more than enough hearing almost everything. The trouble was with the overload of the front end.
As I mention on my previous measurements (posted on this forum), a signal over about S9+25dB will overload the RX of the QCX. So it was not hard for many signals on this contest to do so! Those were very distorted but readable.
The good part was that about 300 400Hz away from the strong signal, the overload just vanished and the weak signals could be received.

Of course is not IC7300 with waterfall and spectrum scope but it was leading me to a good result I guess.

Cannot described the joy to use such a small piece of HW to work DX through pile-up!

You have to try it.

73 de YO3FFF
Cristi
<20210531_091625.jpg><20210531_091638.jpg><20210531_092412.jpg><20210531_092448.jpg>


Roelof Bakker
 

Hello Cristi,

Thank you for sharing your WPX results, which I find truly amazing.
It looks like the QCX+ can be classified as a 'CONTEST GRADE QRP TRANSCEIVER'!

Your antenna must be working very well and apparently there is no lack of operating practice either.

I am running my 40 m QCX+ in WSPR mode and 1W out and have worldwide coverage.
However working the world in a major contest is in a different league.

73,
Roelof, pa0rdt


cris blak
 

Hi Roelof,

Thanks for your kind words. Congratulation for you 1W WSPR QCX station.
I was extensively experimenting with U3S on WSPR and was doing a great job.
By the way, I'm thing to use the calss E PA from QCX to the U3S. 5W with such a cool working class will do a very good job.

You are right about the contest with QRP...doing QRP traffic on a quiet band not in the contest is one thing comparing with running like a dog after as many QSOs as possible in a contest.

So you should try yourself with a little RIG such as this. If is so fun!
One who did not had this experience after using the top class transceivers cannot understand the sensation so don't judge me wrong HI!

Regarding the antenna...as many of us know already, antenna is fifty. I think the other fifty is the propagation. One without the other is nothing.
My antenna is nothing fancy. It is a double INV.V for 80/40m hanged on top of 9.5m aluminum pipe with...feed by 60m RG213 coax. The build is about 30m high close to the Bucharest downtown. Amazingly there is not too much 40m man made noise but awful on 80m (S9 sometimes over S9!).

Good luck with your QCX and maybe one day we will meet on 40m CW!

73 de YO3FFF
Cristi

Pe marți, 1 iunie 2021, 23:12:51 EEST, Roelof Bakker <roelof@...> a scris:


Hello Cristi,

Thank you for sharing your WPX results, which I find truly amazing.
It looks like the QCX+ can be classified as a 'CONTEST GRADE QRP TRANSCEIVER'!

Your antenna must be working very well and apparently there is no lack of operating practice either.

I am running my 40 m QCX+ in WSPR mode and 1W out and have worldwide coverage.
However working the world in a major contest is in a different league.


73,

Roelof, pa0rdt






John Kirby
 

   
Hi Cris,

Well done, two thumbs up ! !

Thanks for sharing.

I am curious about your tuner ...
If not a series L-C please describe.

TNX es 72 73
John
N3AAZ


Roelof Bakker
 

Hello Christi,

30 years ago, I have done some QRP contesting using a rather complicated transceiver for 80 and 40 meter
of my own design. It was a double conversion superhet with an x-tal filter at 1400 kHz, 2500 Hz wide and
a second one on 250 kHz, 500 Hz wide. It could have been made much simpler, yet I wanted to use the
filters at hand. The QCX is a far more elegant design.

In fact, I have participated in last weekend WPX on 80, 40, 20, 15 and 10 m with 5W from a FTdx3000 into
a 2 x 16 meter doublet. Never used a computer for contesting before, so had to become familiar with N1MM
contest software and only used S&P. Logged 260 Q's in a limited time span and this was much easier than
anticipated. There are a lot people on the bands with good ears!

The last 18 years, I have had a lot of fun chasing non directional beacons at longwave which typical use
a keying speed of 10 WPM or less. Contest exchanges are at the other end of the speed spectrum, though!

Anyway, contesting is just another way to test one's station, operator included.

73,
Roelof, pa0rdt


cris blak
 

Hi John,

Thanks for the "two thumbs up" :)

Regarding the tuner...it is a simple "L tuner". Looking from QCX toward antenna it is a variable capacitor to the ground and series inductor on a T50-6 toroid.
I measured the antenna impedance at the end of the coaxial cable with a VNA than using an "online calculator" for L matching network I ended up to that two components design.
Than I used VNA to tune it properly and then an SWR meter to tune the QCX. The circuit is wide enough not needing to be re-tuned on 7MHz CW side.

So no fancy "tuner", just an L-match circuit.

73 de YO3FFF
Cristi

Pe joi, 3 iunie 2021, 13:47:00 EEST, John Kirby <n3aaz_qrp_1@...> a scris:


   
Hi Cris,

Well done, two thumbs up ! !

Thanks for sharing.

I am curious about your tuner ...
If not a series L-C please describe.

TNX es 72 73
John
N3AAZ


John Kirby
 

  Thanks Cristi

""So no fancy "tuner", just an L-match circuit.""

Fancy or not :) hi HI
The Smith chart proves the "simple L"  can match d-c to day-light

72 73
John
N3AAZ