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Re: output on qcx-mini

Gary Bernard
 

That's no problem at all.
Gary W0CKI


-----Original Message-----
From: Don Blachura via groups.io <haircutter@...>
To: QRPLabs@groups.io
Sent: Tue, May 18, 2021 9:53 am
Subject: [QRPLabs] output on qcx-mini

Was wondering ,is it ok to get 7 watts out on qcx-mini. Looking at watt meter and shows 7 watts??

Don..w2xb


output on qcx-mini

Don Blachura
 

Was wondering ,is it ok to get 7 watts out on qcx-mini. Looking at watt meter and shows 7 watts??

Don..w2xb


Re: Using TinySa with QCX+

N3MNT
 

Depends on what you want to do.  The QCX will easily damage the Tina SA if you do not use the proper attenuator.  Check You tube for some excellent tutorials on what you wish to do. 


Re: A simple QCX AGC #mods #qcx

rentwist@...
 

Hi Group,

I built three of ohwenzelph's AGC PCB's.  I only need one.  So, I have two I'd like to offer for sale.  To USA only, $15 USD Paypal Friends and Family only.  Please email with interest.

See attached picture.

Thanks and 73,

Robert, WA2T



 


Re: Digital AGC for QCX

Colin Weaving
 

Hi Julian

I am following this thread with interest. Unfortunately I do not have the technical background to fully understand your efforts, but I have had many years of building Audio amps and filters(including agc) , with varying results. 

This does not make me an expert or an Elmer. Far from it. However “following” and “copying” has given me much pleasure and occasional satisfaction, so its great when others share their knowledge. I have a number of small QRP rigs homebrewed from either scratch or kit format. However any skills I have developed stop when software is involved.

I was particularly interested in your thoughts about the possibility of being able to repeat a missing CW letter and then slowly “catch up”. I taught myself CW when I retired. The self discipline to ignore a missed letter was so difficult and invariable it lead to missing several letters. Others may differ.

I am intrigued how your efforts develop.

Colin M3WCK




On 18 May 2021, at 14:26, Julian N4JO <n4jo@...> wrote:

Thank you Robert; I suspect we are all more like that than we realize. We humans like to think we're so unique but in truth there are more characteristics and needs that bind us than divide us; we just forget it once in a while. In an effort to distinguish ourselves from others in order to know ourselves, we can go so far as to isolate ourselves and, paradoxically, achieve the opposite.
--
Julian, N4JO.


Using TinySa with QCX+

Stephen/Betty Loftus#14840
 

I have never used a  Spectrum Analyzer.  So any information would be very helpful.  My main concern is how to correctly connect the TinySA to the QCX+.

Thanks
Steve KA1ROI


Re: Digital AGC for QCX

 

Thank you Robert; I suspect we are all more like that than we realize. We humans like to think we're so unique but in truth there are more characteristics and needs that bind us than divide us; we just forget it once in a while. In an effort to distinguish ourselves from others in order to know ourselves, we can go so far as to isolate ourselves and, paradoxically, achieve the opposite.
--
Julian, N4JO.


Re: measure power output and harmonics with oscilloscope

Steve
 

In the US I purchased from RandL Electronics.  $54.95 + $8.50 shipping. In stock now.



Glory to God in the highest, and on earth peace, good will toward men. Luke 2:14


On Tuesday, May 18, 2021, 08:11:11 AM EDT, ohwenzelph via groups.io <ohwenzelph@...> wrote:


Which tinySA should I buy and who should I get it from?
thanks
jt aa1of


Re: Power output for the QCX mini 20m version #20m #power

ke9uw
 

BTW, I use the QRPoMeter. Pretty handy digital meter/dummy load. Fun to build too.


Re: Power output for the QCX mini 20m version #20m #power

ke9uw
 

I did the same and got 4.5 watts out starting out at 3. If I get 4 or more, I quit.


Re: measure power output and harmonics with oscilloscope

ohwenzelph
 

Which tinySA should I buy and who should I get it from?
thanks
jt aa1of


Re: New QCX+ 40m failure on first start

Mont Pierce KM6WT
 

On Tue, May 18, 2021 at 01:02 AM, Mont Pierce KM6WT wrote:
Yep...  installing 1K ohms at R46 would definitely mess up the Voltage Dividers for S2 & S3.
Just for the fun of it, let me see if I can guesstimate the voltages you measured when S2 & S3 were pressed:

S3 pressed = (5V * 1,000) / (1,000 + 10,000)
S3 pressed = 0.45 V (+/-)     at  IC2 Pin 26

S2 pressed = (5V * 1,000) / (1,000 + 3,300)
S2 pressed = 1.16 V (+/-)     at  IC2 Pin 26

Rotary button would not have been affected:
Rot pressed = (5V * 1,000) / (1,000 + 0)
Rot pressed = 5 V


73
km6wt



Re: New QCX+ 40m failure on first start

Mont Pierce KM6WT
 

On Mon, May 17, 2021 at 10:47 PM, Tony McUmber wrote:
The very last two electronic connections I made before applying the power were the resistors R45 and R46.  I had transposed them.
Glad you found it Tony.

Yep...  installing 1K ohms at R46 would definitely mess up the Voltage Dividers for S2 & S3.


73
km6wt


Re: New QCX+ 40m failure on first start

Tony McUmber
 

Hey, Mont,

I too check resistor values with a meter before installing them.  That does not prevent me from mis-installing them, however.

This was the cleanest assembly I have ever done, with tight coils, components set snug with the board, no burned traces or blobs or whiskers.  Everything is beautiful, except it didn't work.

Many of the boarders here, including yourself, gave me useful information, of which I made use.  Still, I felt the need to ask Hans.  He replied graciously (try to get better service, I dare you!) and gave me a couple of hints.  This would be my AHA! moment.  I realized that the voltages that are read from the switches by the processor did not emanate from resistors near the cpu, but on the front panel between the switches.  The very last two electronic connections I made before applying the power were the resistors R45 and R46.  I had transposed them. The very last chance to make an error, and I did it!  Finally correcting that was super easy and immensely satisfying.

Thanks to you and to all the others who offered suggestions.

73, Tony N0BPA


Re: Digital AGC for QCX

Robert AG6LK
 

Hi Julian,

Thank you for sharing your history with me. We see things alike, in many ways.

Take care my friend,
Robert, AG6LK


Re: Digital AGC for QCX

 

I'm not married to the specific hardware, I'm committed to getting the best for the least. I'll do whatever it takes :-)
More specifically, the heart of this project is the monitoring, detection and burst-synchronous gain control algorithm (in other words, trying to keep the letters in words at the same level, and as fade-free as possible, to minimize difficulty in decoding and, of course, blowing your eardrums out) and as such it needs to be sensitive to the pass-band of the digital filter, not to all the junk that accompanies the CW information. It's a different set of requirements to what would be required of a hi-fi receiver or a studio grade digital audio processing system. As previously stated, I can easily clean up a slightly grainy PWM-rendered CW signal by active filtering.
All that said, once the primary algorithm is in place, the input and output processes can be refined on a budgetary basis. If you want a Teensy version, I'd be happy to do one: the 4.0 has two A2Ds and a real DAC: more than adequate for the "GT version " :-)
Just to whet your appetite further, though, and make my point, with the capability in the Teensy I could even include a repeat and catch-up function, just like a TV Video recorder.
How many times have you missed a letter, a word, and lost your sense of timing? This feature could, at the press of a button,  go back a word or so, and start to replay the recorded CCW, slowly catching up to current time (by chopping out tiny fragments of sound), if  you so wished.

Once we go digital, we have a platform for development upon which many things are possible. It just takes imagination to fuel it, and a customer to want it. That's where you come in, and believe me, I am listening: there is no point in doing this just for myself.
--
Julian, N4JO.


Re: Digital AGC for QCX

VE3VXO
 

Oh, I thought you were just going to use the Nano's cpu for shifting the data through memory and rely on external hardware for the conversions.  I think you are going to find that you need a lot more bits than the little 328 can provide to preserve the audio quality and the dynamic range of the receiver.  For the SOTA portable angle, I think the simple diode limiter or the nice analog AGC using the MOSFET in parallel with the mute switch would probably be hard to beat, but that is just my opinion and I'm not trying to rain on your idea which I think is pretty interesting conceptually, but it is going to put some serious demands on the conversion hardware side of things.


Re: Power output for the QCX mini 20m version #20m #power

Skip Davis
 

Christian,
Start by removing one turn only from L3 and then expand or compress the turns on L1&2. I just unwind one turn and tack solder the wire back to check BEFORE CUTTING THE WIRE to length.
Just remember that spreading the turns reduces the inductance and compressing them increase it. So if after removing one turn from L3 and spreading them out still increases output them unwind one more turn to see your results. Getting about 4 watts out is good for the 20m QCX when you’re are using about 12vdc for power, that is what I use as a start voltage which matches my portable battery pack ( about 12.8 vdc charged after resting).

73, Skip NC9O


Great Little Transceiver

John Dziedziejko
 

I finished building the 40 meter mini kit over the weekend. Applied power then did adjustments and calibration. Hooked up my QRP power meter and dummy load, got 5 watts output with no adjustment of the toroid windings. I used my inductance meter to check the number of windings to get me close to values as indicated in the assembly manual. I did remove a couple of windings on several of the toroids. The decoder works great. 


Thanks for a great kit, had fun building. Now wanting to build another kit, no sure if I should get the 17 or 10 meter kit?

John W9QP 


Re: measure power output and harmonics with oscilloscope

jmh6@...
 

Hi All,

At first look it would 'seem' that 8 bit ADC cannot give more that 48 db range. Given the presence of noise and other signals, the ADC values get smeared together and if the 8bits are pretty linear an amazing dynamic range is often observed.

If you put a very clean signal in though, the dynamic range can disappear into jumps in value and other curiousities.

Measurements are a fun area :).

I think it would be fun to use QCX as an FFT measurement front end. I expect it would do amazingly well.

Linrad provided a keyboard method to remove bits from the input signal. There was an amazingly small measurement difference as the bits were dropped down to 6 or even 4 bits.

Lots of fun :).

On Mon, 17 May 2021, Hans Summers wrote:

Hi I
Remember that most oscilloscopes have an 8-bit AGC which means a maximum theoretical dynamic range of 48dB, and practically speaking somewhat less than this. I am not 100%
sure this equates to 48dB maximum useful dynamic range on the FFT function, perhaps someone could comment on that? Certainly though I have never believed the FFT function
of even my 12-bit ADC 'scope has any practical value, though maybe I am wrong. 
I was a beta tester on the Tiny SA development program, I have both a pre-production model (with certain faults) and a production model; I did at some point measure a QCX
output spectrum and compare it to my professional Advantest R3361C Spectrum Analyzer, and the two were within 1dB of each other, down to the noise floor of the TinySA. I
think the TinySA is a great value little piece of equipment that is very useful for amateur radio purposes. 
73 Hans G0UPL
http://qrp-labs.com
On Mon, May 17, 2021, 20:25 Ben <ben@1k2.nl> wrote:
I have ordered a 50 ohm feed through terminator. So I can measure directly without the probe to the scope. I'll update this topic.

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