Date   
Re: VFO Output – Is This Right???

Graham, VE3GTC
 

Pietro,

What you describe sound correct for the way you were connecting your oscilloscope to have a look.

Oscilloscopes are very handy instruments but do require care in their use.

You may find these links helpful:

https://www.youtube.com/watch?v=zodpCuxwn_o  oscilloscope ground lead length effects.

https://www.youtube.com/watch?v=SX4HGNWBe5M   basic 1x and 10x scope probe tutorial

https://www.youtube.com/watch?v=-4q8geE5ef8  How to make a high performance oscilloscope probe socket

https://www.youtube.com/watch?v=OiAmER1OJh4  mysteries of 1x scope probes

https://www.youtube.com/watch?v=oxJQr4dKnys  importance of 10x probe compensation.

The first three videos are by W2AEW and quite well done. He has over 300 videos posted on youtube.

The last two are by Dave Jones of EEVBLOG fame. Also well done and he also has many videos posted.

You may also find this document useful:

https://www.sitime.com/api/gated/AN10028-Probing-Oscillator-Output.pdf

cheers, Graham ve3gtc


On 2019-06-21 18:40, pietromartini2007@... wrote:

I built the VFO/Signal Generator kit with no problems, and it started up right away. However, the output waveforms and amplitudes are not what I expected; according to the manual, they should be square waves with an amplitude of 3.3V p-p. Taking the output from the CLK0 pad, what I see on my scope is sort of a square wave at 3.5 MHz with a lot of overshoot and undershoot, and as the frequency increases the waveform becomes more of a triangle and the amplitude steadily decreases, until it’s only 246 mV at 150 MHz, and the waveform is almost a sine wave. I don’t have any load on the output, and I attached the scope probes directly to the CLK0 pads. If I had to guess I’d say stray capacitance may be the culprit. So can someone tell me if I have a problem with my build? I’m attaching a few photos of the scope images.

Re: My QCX is locked in a transmit cycle...

Steve in Okinawa
 

Hello Saku,
 
It is not difficult to remove those parts. Many techniques have been described in this forum.

I'm glad the QCX did work before, and i am sure you can fix it.

72,

JS6TMW 

Re: Shipping route question

 

Bill, the only way I can see Hans improving his kits is if he was to start using tubes. :) Kidding of course, sort of.

I've never had to sign for a QRP Labs package. Maybe that changed or maybe it's because I still live far enough out of a small enough town that my mail service is "old school". The mail carrier even gone so far as pick up a FedEx package that FedEx left on the ground by the mail box by the side of the road and stick it in the mailbox for me (FedEx can't do that). The mail box is 150' from the house :) 

Nothing urgent. Like I said in the first post- "It'll get here when it gets here. I'm in no particular hurry".
--
73
NE5U

Mike

Re: Large inductors in GPS supply and data lines ?

 

Update.

I removed the huge r chokes and replaced them with some smaller ones.

I ordered some chokes, the type that are really just stiff wire with some ferrite moulded on to them

I measured the XL at HF, typically 40 ohms, and about 0.5 ohms down at 100Khz.

Presumably lower at the 1pps and 9k6 data, and the GPS now works properly ;-)

Lesson learnt.

For info, the symptoms of having too much inductance in the GPS leads was erratic 1 pps heartbeat showing.

For example, maybe every 10 beats there was a 2 pps or similar, the calibration windows whizzed by in a  few seconds ,
despite being told to do a calibration for 20 seconds, and occasionally times reported such 104:31:23 UTC !!

So now we know.

73 de Andy

Re: Shipping route question

 

The Turkey question was purely curiosity. That was not the home of QRP Labs when I ordered the piles of WSPR receivers, bandpass filters, clocks, etc. that I have bought and assembled over the years but I haven't ordered in a while. Things change and all that jazz.

Time spent enroute - agreed. All things considered it made it to the US pretty quickly.

Time spent in the state of New York... that's the one that makes no sense to me. 3 days and still hasn't shipped from Jamaica, NY.

Like I said in the second sentence, "It'll get here when it gets here. I'm in no particular hurry."

Based on the tracking for this shipment I changed the delivery location for the two QCX kits that I just ordered.

--
73
NE5U

Mike

QCX Message Preset Programming

MA
 

Does anyone know the procedure to program the QCX preset messages using paddles and the decoder?

Marc
call: WA9ZCO
cell: (920)671-4266


--
Marc

Re: VFO Output – Is This Right???

James Daldry W4JED
 

Hi, Pietro

First - what is the bandwidth of the scope you are using? To properly see a square wave the scope cutoff frequency has to be at least 5 times the fundamental frequency of the signal.

Next - how is the probe grounded to the source? If you are looking at signals of more than a few megahertz the ground should be a short wire wrapped around the ground ring on the probe and soldered to the ground side of the output connector on the device. Even a couple inches of wire is too much. It will add the overshoots that you are looking at.

Next - are you using a X10 probe? While the cable into the scope is coaxial, it is not terminated with a 50 or 75 ohm resistor inside the scope unless it is specifically made for looking at 50 or 75 ohm systems. With a 50 ohm impedance at the input and a 1 megohm resistance inside the scope the cable will ring like a bell. Using a properly adjusted (!) X10 probe will disconnect the input capacitance of the scope from the signal generator and make the display truer. If you don't know how to calibrate the probe, read the manual.

Good luck.

73

Jim W4JED

On 6/21/19 2:40 PM, pietromartini2007@... wrote:

I built the VFO/Signal Generator kit with no problems, and it started up right away. However, the output waveforms and amplitudes are not what I expected; according to the manual, they should be square waves with an amplitude of 3.3V p-p. Taking the output from the CLK0 pad, what I see on my scope is sort of a square wave at 3.5 MHz with a lot of overshoot and undershoot, and as the frequency increases the waveform becomes more of a triangle and the amplitude steadily decreases, until it’s only 246 mV at 150 MHz, and the waveform is almost a sine wave. I don’t have any load on the output, and I attached the scope probes directly to the CLK0 pads. If I had to guess I’d say stray capacitance may be the culprit. So can someone tell me if I have a problem with my build? I’m attaching a few photos of the scope images.

My QCX is locked in a transmit cycle...

Saku JP3OUG
 

Hello.
I'm JP3OUG, Saku.
I built QCX40 a week ago.
It was working fine at that time.

But now, it isn't working fine.
It is locked in a transmit cycle although I don't connect a paddle.
When keyer mode(4.1) is set to Straight, I hear the continual beep (-----).
When keyer mode is set to IAMBIC, I hear the Intermittent beep (•-•-•-...).
But when I push the left side button(Displayed as "Speed 12"), The beep stops and I can hear CW signal.

And the Beacon(6.1) has been turned off .

I tried to remove a stereo connector for paddle and a micro switch for straight key.
But I couldn't remove them because I can not remove the solder well.

Please tell me how to remove them and other possible causes for this problem.
73 DE JP3OUG Nishigaki Sakutaro

Re: Shipping route question

Bill Cromwell
 

Hi,

My signature was not required for my delivery from QRP Labs. I wonder why yours was and mine wasn't. As for the time it took - I ordered it one day and it was delivered "some other day". I waited 72 years to order those goodies so a few days one way or another made no significant difference:) If it was some kind of urgent I would have ordered it forty years ago!

73,

Bill KU8H

On 6/22/19 7:23 AM, Don--AE4DW wrote:
As Allison said, 8 days to get from Turkey to US is phenomenal, definitely better than I've experienced; my two shipments were in the mid 20 day range both times, that's typical based on Hans' published data. Turnaround time once in Jamaica was 24-48 hours. From what I have seen with US shipments from Turkey, Jamaica (JFK Airport, etc) is the acceptance point for all of them.
You're in the home stretch..don't fret! Also remember signature is required for delivery.
My bet is, 25% chance of delivery on Monday, 75% chance on Tuesday, and sure bet you'll have it by Wednesday. Hopefully the USPS won't make me look bad, lol.
--
bark less - wag more

Re: Shipping route question

Don--AE4DW
 

As Allison said, 8 days to get from Turkey to US is phenomenal, definitely better than I've experienced; my two shipments were in the mid 20 day range both times, that's typical based on Hans' published data. Turnaround time once in Jamaica was 24-48 hours. From what I have seen with US shipments from Turkey, Jamaica (JFK Airport, etc) is the acceptance point for all of them.

You're in the home stretch..don't fret! Also remember signature is required for delivery.

My bet is, 25% chance of delivery on Monday, 75% chance on Tuesday, and sure bet you'll have it by Wednesday. Hopefully the USPS won't make me look bad, lol.

 

 

Re: QCX 17m PA problem

Axel
 

Hi,

I had problems with low output power, too, and want to report what I did to fix my problem. Maybe it helps other people.

My QCX is for 20 m.

I removed c29 and measured the LPF with a VNWA. Edge frequency of the LPF was a little to low and I removed 2 windings from L1, L2, L3 each to get the desired filter response. This didn't increase output power significantly.

You can transmit even with the LCD module removed.

I reinserted C29 and put 50 Ohms to output.
With an oscilloscope, I measured voltages at output (Vout) and across C25 (V25) and C26 (V26).

For ideal components (exact value, no losses) it should be (20 m):

V26 = V25
V25/Vout = 1.36

I measured:

V26/V25 = 1.27

Power loss is approximately:

(V26/V25)^2 = 1.6
meaning about 60% of power is lost between C26 and C25. That's much.

V25/Vout = 1.44
should be 1.36

Power loss:
(1.44/1.36)^2 = 1.13
meaning 13% of power is lost from C25 to output, not to much.

I replaced C25 and C26 by NP0 (C0G) SMD capacitors (NP0 SMD was easier to get than THT).

I damaged (not completely destroyed) 74ACT00, resulting in high somewhat lower output power and about 0.22 A RX current. (78L05 getting hot).
I replaced 74ACT00 and put it on a cheap socket (seems to be no problem).

Now:

(V26/V25)^2 = 1.23
meaning about 23% of power is lost between C26 and C25. Significantly better now.

Other measurements now (20m):
Vdc = 12.1 V (at output of reverse polarity protection diode)
Idc = 0.35 A (TX minus RX)
Pin  = 4.2W (Tx minus RX)

V26 = 26Vp
V25 = 24Vp
Vout = 17Vp

Pout = 2.9W

Hope it helps
Axel DF1ET


Re: #QCX : Is toroid's manufacturer Amidon? #qcx

Axel
 

Thank you for the hint. - I now found out, that while doing my measurements I accidentally damaged (not completely destroyed) the driver IC 74ACT00 and hence missinterpreted the result. Significant power loss didn't result from toroid cores but from capacitors.

Axel

Re: VFO Output – Is This Right???

Richard G4TGJ
 

What's the bandwidth of your scope? A square wave is formed from a lot of harmonics so if they are being attenuated then it won't stay square.
--
73
Richard
G4TGJ

Re: QCX Message Preset Programming

Alan G4ZFQ
 

What is the procedure to program the QCX message program using paddles?
Marc,

Reading the manual 4.17, 4.18 might help.

73 Alan G4ZFQ

Re: Add Power Switch to my QCX Enclosure #enclosure #qcx #mods

Steve in Okinawa
 

These cutting drills make short work of irregular holes in plastic and soft metal. This set was only a few dollars on eBay.

Re: Add Power Switch to my QCX Enclosure shapes

Steve in Okinawa
 

 these cutting drills also make short work of irregular shapes in plastic and soft metals. They are best used in a drill press. The set was only a few dollars on eBay.

VFO Output – Is This Right???

pietromartini2007@...
 

I built the VFO/Signal Generator kit with no problems, and it started up right away. However, the output waveforms and amplitudes are not what I expected; according to the manual, they should be square waves with an amplitude of 3.3V p-p. Taking the output from the CLK0 pad, what I see on my scope is sort of a square wave at 3.5 MHz with a lot of overshoot and undershoot, and as the frequency increases the waveform becomes more of a triangle and the amplitude steadily decreases, until it’s only 246 mV at 150 MHz, and the waveform is almost a sine wave. I don’t have any load on the output, and I attached the scope probes directly to the CLK0 pads. If I had to guess I’d say stray capacitance may be the culprit. So can someone tell me if I have a problem with my build? I’m attaching a few photos of the scope images.

10 watt amplifier by KA6PSD

rbeswick@...
 

I just finished the transformers this evening. Had to put on my glasses to see clearly,  the toothpick trick worked flawlessly. Now to find a quiet time to solder them in. Used a sharpie to color the primary wires for easy identification and marked the torrid wire the sharpie to identify the 5 from the 6 winded transformers. It will be a slow build as the eyes need breaks, and slow and steady wins the race. 
I will keep everyone informed as I go along.
Robert KA6PSD

QCX Message Preset Programming

MA
 

What is the procedure to program the QCX message program using paddles?

Marc
call: WA9ZCO
cell: (920)671-4266


--
Marc

Re: Shipping route question

ajparent1/KB1GMX
 

Start in Turkey as theat is the home of QRPLabs..

The Jamaica NY center is likely one of the busiest for international 
shipments.

3 weeks is normal.    Two weeks would be incredible luck.

Allison