Date   
QCX - Can't adj band pass or audio (initial adjustment)

Larrie
 

Hi

I am new to the group and just completed by QCX transciever for 17m band.  When I try to do the initial adjustment I do not seem to have enough power.  For the Band-pass trimmer adjustment, I have a scaling factor of 06, the amplitude bar goes about 70% across, but adjusting C1 had no effect at all.  Moving onto the audio adjustments (8.8, 8.9, 8.10) the scaling factor at best is 03 (volume control full on).  Adjusting R27, R24, and R17 does move the amplitude bar a little.  I checked the voltages and all seemed OK.  My source was 14 V, so I did get some voltages on the IC's about 1-2 v higher, but the relative voltages on all the pins appeared to be as expected.  However, there are a couple of exceptions. 
IC9 - all pins read ~12v (14 V supply).  C43, C45 are low at 1.6 V(expect 2.3).  Test pins 0, and 1 are 1.7V and C2 is 3.4 and D2 is 5V.  The software seems to be functioning fine.  I do hear the 700 Hz and 600 Hz tones as expected during the alignment

Any ideas of what might the issue or what I should check next? Thank you.

Larrie
AF7NU

Re: New RF devices in low cost packages

Razvan (M0HZH)
 

Some good info on these cheap LDMOS transistors. 600-700W from 2x £29 devices is pretty good in my book.

https://qrpblog.com/2019/10/a-600w-broadband-hf-amplifier-using-affordable-ldmos-devices/

Re: LPF 630 meter problem - low output

Ronald Taylor
 

Allison, I believe he is talking about the QRP Labs 5 watt amplifier kit on his U3S WSPR rig. He used an 80 meter LPF for 80 meters and is using a 630 meter LPF for 630 meters. 

On Sun, Oct 27, 2019 at 16:02 ajparent1/KB1GMX <kb1gmx@...> wrote:
Ronald,

The amp is not a broad band design its class E switching and certainly not broadband.
They generally perform better at lower frequencies if the tuning is right.
IF the tuning is not close the switching if the output MOSFETS is not right
and the efficiency goes down seriously. 

Its like pushing a swing, push at the wrong time and your effort goes way up,
and you may not go higher.

There might be filter issues if the values are wrong but first the L4/C3 pair must
be band appropriate.

Allison

Re: DL6OWT U3S balloon

James Zelazny jr <wtfbsyt@...>
 

As suspected...too far North today.
Ran a Hysplit trajectory from the previous and see the most unusual trajectory I have ever seen before.
Curious what it will look like in 2 days.

Re: New Member Saying Hello

Jordon Posey
 

I'm still pretty new when it comes to CW. One resource that helped me was LCWO.net. It starts you out with just 2 letters and adds more as you progress. And I would recommend a small project before you order a QCX. I made a small alarm clock from a kit. It was simple and a fun project to do with my SO. Most importantly, it boosted my confidence in soldering.

73, KN4SKY 

On Sun, Oct 27, 2019, 2:14 PM Mark K0ABD via Groups.Io <mboston72=yahoo.com@groups.io> wrote:
Thanks for the quick reply, Gary, Jack, & Jordon.

I don't know exactly when I'll be purchasing a kit. Right now I'm researching. I have not prior experience with this. I have to read-up on the instructions. So it may be a couple months before I purchase.

Originally I didn't want to build my own from a kit because of the time involved. I will also have to learn CW, that from what I understand, is a bit of a task.

However, based on what I've found so far, these are newbie-friendly kits that first-timers can put together. The support forum is another plus.

Thanks,

Mark, K0ABD

Re: DL6OWT U3S balloon

john
 

Thanks for this! Fascinating

John K5MO

On 10/27/2019 7:00 AM, James Zelazny jr wrote:
A simple summary of DL6OWT progress so far.
Since it vanishes more often than not,I added the missing paths manually.
Blue is where it made first lap back to Germany and the Orange is second where 2.5 is current location.
Actual telemetry will still show here as it is received in real time - https://www.qsl.net/n2nxz/stella23.html
Jim
--
III

Re: DL6OWT U3S balloon

David R. Hassall WA5DJJ
 

Dear Dan,
Your  balloon is doing well.  It is a real challenge to try to track because of its limited transmission time but that is what really makes it FUN!   I  have been on it since round 1.   But so far I have not found it on round 3.   Hoping that when it comes out of the northland the wind will send it right over the top of my station in the bright New Mexico Sun.  
Take care and have fun
73 Dave WA5DJJ

Re: LPF 630 meter problem - low output

ajparent1/KB1GMX
 

Ronald,

The amp is not a broad band design its class E switching and certainly not broadband.
They generally perform better at lower frequencies if the tuning is right.
IF the tuning is not close the switching if the output MOSFETS is not right
and the efficiency goes down seriously. 

Its like pushing a swing, push at the wrong time and your effort goes way up,
and you may not go higher.

There might be filter issues if the values are wrong but first the L4/C3 pair must
be band appropriate.

Allison

Re: LPF 630 meter problem - low output

ajparent1/KB1GMX
 

I'm surprised your getting a watt!

The value of L4 and C30 must be suitable for 630M the 80M coil and cap will not do it.

for class E (and power) the L2 C30 must be resonant with the output filter in place.
IF the 80M coil is used (L4) at 472khz its nearly a short circuit.

Suggested values are 17.5uh and C30 is more like 1300-1400pF.  Even then
you may have to play with the values.

Using that ring (read, t37-2) you need about 65 turns (give or take) of wire for 472khz.
Using a FT37-61 material toroid its about 17-18 turns. 

The big guy T1 has to have a lot more wire for the same reason if RX is to work well.

Allison

Re: WSPR

geoff M0ORE
 

Instead of a heatsink on something that does not generate any heat ( if it does, then you are in serious trouble ) encase the crystal in a block of insulation such as polystyrene. Difficult to do with the crystal supplied but can be done.

On 27/10/2019 18:24, Bill Allen wrote:
For the last few days, I have been enjoying the WSPR feature of my QCX 20 meters.  I have been spotted all over the country and even Hawaii and Africa.  Good times! There are two issues that I don't know what to think about:
First thing is that while operating in beacon mode at a frequency of 14.097.110, If a station comes up on VFO "A" (which is set on 14.060) then I can hear them quite well. I'm not sure that this is quite right.?
The second thing is drift. Looking at the WSPRNet database I find that my drift is pretty consistently -3 and -4.  I have added a heatsink to the 20MHZ crystal and am using a 35AMP Astron linear power supply. I am not using the QLG1 as I have not been able to get it to work at my QTH.  My QCX has the 1.01a revision.
Comments?

W8BH Morse Tutor

Ken KM4NFQ
 

Greetings Hans, and group,

First of all, thank you very much Hans for the excellent QCX kit. I
know that it made its debut at the Youngsters On The Air Summer Camp
2017 and has since been distributed to a worldwide audience.

With Youngsters in mind, and the QCX being a CW rig, I would like to
point all parties interested in learning the Morse code, or improving
their Morse code skills to the W8BH Morse Tutor: http://w8bh.net/

There you will find a multi-part Morse Tutor tutorial, which includes
a builder's guide for those interested in building their own device,
as well as a User Guide which explains all the features available.

Full source code for the project is available at:
https://github.com/bhall66/morse-tutor

The GitHub repository has all the source code for the Morse Tutor
Tutorial, as well as the complete source code for the finished
project. Gerbers are available for those who wish to order their own
PCBs.

There are two official versions of the W8BH Morse Tutor available. One
uses a 'Blue Pill' development board, and the other one uses an
'ESP32-WROOM-32' development board. The ESP32 version allows two
people to send code back and forth between themselves.

Bruce Hall W8BH has released this project under an MIT license. The
W8BH Morse Tutor is under active development, so please see the above
GitHub repository for the latest version.

W8BH is NOT offering any pre-made kits or PCBs. However, this is a
great project for an Amateur Radio Club to build if there is enough
interest. I have built the 'Blue Pill' device and I am extremely
pleased with it.

Regards,
Ken, KM4NFQ "Not Fully Qualified"
https://github.com/muurtikaar/mega-morse-tutor

Re: WSPR

Tony McUmber
 

I can't speak to the spurious reception while you are in beacon mode, but I have not encountered that phenomenon on my QCX 40. 
As for frequency "drift," bear in mind that the receiving station may be lying to you.  Best to use a known frequency check locally than depend on another station's electronic opinion, especially since you are getting different reports from different stations.  I don't have such a source myself, because I am saving my pennies (insert suitable currency name instead) for a QR you-know-what.

If you need help figuring it all out, this crew on this forum can help you with that.  I have been spotted all around the world with my two watts because magic.

73, Tony N0BPA

Re: LPF 630 meter problem - low output

Ronald Taylor
 

Hi Emory. Do you know for sure your amplifier is making 5 watts output? Actually that can’t be measured accurately with a wattmeter before the LPF anyway because it is a somewhat square waveform there. If indeed 5 watts are present on 630 meters at the input of the filter, the loss you see is still less than 1 dB. The best way to check the filter is with a Spectrum analyzer and tracking generator. These filters usually have very little loss, like less than 0.5 dB in the passband. The analyzer/generator will show the actual curve and you can see anywhere in the passband what the actual loss is. Without those tools you can use a signal generator into the filter and some means to monitor the output, either an RF voltmeter or a scope. Make sure both ends of the filter are properly terminated with 50 ohms. The generator should terminate the input if it is designed with a 50 ohm output. Adjust the frequency upward from some low spot. As it goes up, record the level at various frequencies and plot it on a piece of paper. If the knee of the curve is relatively close to the desired operating frequency then it’s possible you have too many turns on the toroids. If the knee is well above the operating frequency and the pass characteristic is very flat up to the point where it starts to drop off, then the filter is probably fine, and you probably aren’t really getting the power out of the amp that you think you are. Broadband amplifiers don’t necesssarily have a flat gain characteristic across their operating range. At the low end, power might drop off due to the characteristics of some of the components, like ferrite cores used for wideband transformers and RF chokes. 

All that said, less than 1 dB of loss won’t be measurable at the other end of the link, and I don’t think you’ll find that the filter is the issue here when comparing 630 meter performance to 80 meter performance of the amplifier itself … Take care ..

73 …. Ron



On Sun, Oct 27, 2019 at 1:43 PM Emory Haines <wm3m73@...> wrote:

I recently built a QRP Labs LPF kit for 630 meters, 474 khz.  Using it with a QRP Labs 5 watt PA in one of my Ultimate3 WSPR kits, the max power out is only just over 1 watt.  When using the 80 meter LPF output is 5 watts in same configuration.  I am using a OHR RFL-100 dummy load and a OHR WM-2 Wattmeter.  Watt meter is good to down to 300 khz.  I have checked all connections several times on the 630 LPF, continuity is good, all caps and toroids, one side to ground other side connected together.

Any ideas or suggestions on what to try would be greatly appreciated.

Thank you  73

Emory  WM3M

Re: Audio Issues with QCX 20m

Skip Waisner
 

IC5 voltages as expected.  Pin 2 & 14 are the Clk0 and Clk1 test points, correct?  Those measure 4.4v p-p each.  The Freq test point (Clk2) shows no signal on scope.  

Skip
NA5W 

Re: New Member Saying Hello

Mark K0ABD
 

Hi Joe,

Having a look at that one now. Amazing!

LPF 630 meter problem - low output

Emory Haines
 

I recently built a QRP Labs LPF kit for 630 meters, 474 khz.  Using it with a QRP Labs 5 watt PA in one of my Ultimate3 WSPR kits, the max power out is only just over 1 watt.  When using the 80 meter LPF output is 5 watts in same configuration.  I am using a OHR RFL-100 dummy load and a OHR WM-2 Wattmeter.  Watt meter is good to down to 300 khz.  I have checked all connections several times on the 630 LPF, continuity is good, all caps and toroids, one side to ground other side connected together.

Any ideas or suggestions on what to try would be greatly appreciated.

Thank you  73

Emory  WM3M

Re: Audio Issues with QCX 20m

Alan G4ZFQ
 

Sorry Alan, not sure which pins 2 & 14 you mean.
Skip,

IC4 the clocks.

Here are the voltages
that differ from what Hans had listed in the chart:
So all the IC5 voltages are as expected? As they should be connected to the capacitors by only 100 ohms they should be wrong except pin 3.

Did you use your DVM? The readings in the manual are with the internal meter which would explain most of the differences below.

73 Alan G4ZFQ
C44=0.65
C45=0.65
C46=0.65
IC6 Pin3=2.62
IC6 Pin5=2.62
IC7 Pin3=2.70
IC7 Pin5=2.70
IC8 Pin3=2.42
IC8 Pin5=2.49
IC9 Pin3=2.96
IC9 Pin6=1.23
IC9 Pin7=1.23
IC10 Pin5=5.98
IC10 Pin6=6.03

Re: WSPR

Bill Allen
 

After I wrote this and only after, did I think that perhaps I put the heat sink on the wrong crystal . . .
No, I'm saying that I can hear signals that are on the VFO A frequency while in WSPR mode. 

U3S

oliver.cohen1@...
 

Hi All, 

I almost completed putting my U3S in a case when a 5V wire broke free from the GPS and hit the GND of the case. 

The screen displayed 'Updates' and then went blank (back light on) with the upper row full of white squares. 

I assume I have fried the chip and would need to flash a new one. Anyone else have any ideas if im on the right track to solving the issue?

Thanks

Re: WSPR

Alan G4ZFQ
 

Looking at the WSPRNet database I find that my drift is pretty consistently -3 and -4.  I have added a heatsink to the 20MHZ crystal
The 27MHz crystal is the frequency reference.
Drift is not a regular complaint, check the 5 and 3.5 volt supplies.

If a station comes up on VFO "A" (which is set on 14.060) then I can
hear them quite well. I'm not sure that this is quite right.?

I do not understand, are you saying you hear VFO A when set to VFO B?

73 Alan G4ZFQ