Date   

Re: Very Low Power Out #qcx #problem

Ronald Taylor
 

If all the voltages are as specified while in receive mode then IC3 seems to be working. Logic levels are all correct. 

The transmit voltages on IC3 during transmit are square waves in several spots. If using a DVM to measure them be sure to look for about half the expected voltage listed for the square waves. 

Did you measure the signal on pin 4? I didn’t see that in your discussion. That should be the 3.3 volt square wave from IC1 (CLK2 output) and would look like about 1.67 v on your DVM. If that’s not there you won’t get any output. Also pin 5 should have +5v on it. I didn’t see your reading for that one either. That signal is the transmit command coming from the processor. 

Don’t do heart surgery yet. I think that particular chip is fine. 

Good luck 

Ron

On Sat, Nov 24, 2018 at 11:16 <nigelspear@...> wrote:
Hi

Just finished building the QCX (40m). Recieve works beautifully but I have very low power on transmit - about 20mW
My suspicion is IC3, but before I rip it out an replace it, Id thought Id check to see if there could be any causes.
Ive followed the troubleshooting guide posted by Hans and checked the the expected voltages on IC3 with a DVM.

  1. They are all correct on receive
  2. On transmit. Pins 1 and 2 are correct (around 4.2V) but pin 3 is only at 0.5v. Pin11 is at 1.0v (incorrect) and 12&13 are at 0v
  3. This would explain why the FETs are hardly being driven
  4. Also pins 8 and 9 seem wrong 1.0v and 2.5v
Ive checked for any problems around Q7, but the board is clean with no bridges.
L4 is also delivering a health 12 volts to the BS170's

Any other ideas before I attempt open heart surgery?


Re: QCX click on QSK and odd DC readings

Bob
 

Thanks Alan. I'll recheck with the internal meter.
--
73 Bob G3YIQ


Re: QCX click on QSK and odd DC readings

Alan G4ZFQ
 

The voltages Hans quotes are made with the low impedance internal meter.
Hans should suggest connecting something like a 10K across the leads of a DVM..

73 Alan G4ZFQ


Re: QCX click on QSK and odd DC readings

Alan G4ZFQ
 

All measurements were taken with a Fluke 175 DMM.
Bob,

This is where you have gone wrong.
The voltages Hans quotes are made with the low impedance internal meter.

73 Alan G4ZFQ


Here are the readings versus what Hans shows in the manual:
*IC6*
Pin 3 should read 1.63V, actually 2.66V (same as pins 1 and 2)
Pin 5 should read 1.55V, actually 2.66V (same as pins 6 and 7)
*IC7*
Pin 3 should read 1.99V, actually 2.74V, (same as pins 1 and 2)
Pin 5 should read 1.89V, actually 2.74V (same as pins 6 and 7)
*IC8*
Pin 3 should read 0.65V, actually 2.65V (marginally below pins 1 and 2, which read 2.67V)
Pin 5 should read 0.67V, actually 2.67V (marginally below pins 6 and 7, which read 2.69V)
IC9
Pin 3 should read 0.65V, actually 2.65V (marginally below pins 1 and 2, which read 2.67V)
Pin 5 should read 0.67V, actually 2.67V (marginally below pins 6 and 7, which read 2.69V)
IC10
Pin 3 should read 5.83V, actually 6.94V (same as pins 1 and 2)
Pin 5 should read 4.21V, actually 6.93V (marginally below pins 6 and 7, which read 6.95V)
I'm going through checking component placements but if anything shouts out as an obvious error, I'd appreciate the help!
--
73 Bob G3YIQ


QCX click on QSK and odd DC readings

Bob
 

I have my 20m QCX (rev.4) up and running and delivering about 4W after replacing the output RF filter caps with polystyrene types and replacing the reverse polarity protection diode with a P-channel MOSFET to keep the supply voltage up. It's running on a bench power supply that's delivering about 13.9VDC. I noticed a lot of clicks on QSK and searched the forum. I'm using the latest 0.1mfd ceramic caps, as recommended, so that's not the problem.

This afternoon I started running through DC voltage checks. While most measurements are close enough to those in the manual to be accounted for by different supply voltages (Hans used a 12V supply) there are quite a few differences, the most significant of these on pins 3 and 5 of ICs 6, 7, 8 9, and 10. The largest differences are around ICs 8 and 9, highlighted in italics.

All measurements were taken with a Fluke 175 DMM.

Here are the readings versus what Hans shows in the manual:

IC6
Pin 3 should read 1.63V, actually 2.66V (same as pins 1 and 2)
Pin 5 should read 1.55V, actually 2.66V (same as pins 6 and 7)

IC7
Pin 3 should read 1.99V, actually 2.74V, (same as pins 1 and 2)
Pin 5 should read 1.89V, actually 2.74V (same as pins 6 and 7)

IC8
Pin 3 should read 0.65V, actually 2.65V (marginally below pins 1 and 2, which read 2.67V)
Pin 5 should read 0.67V, actually 2.67V (marginally below pins 6 and 7, which read 2.69V)

IC9
Pin 3 should read 0.65V, actually 2.65V (marginally below pins 1 and 2, which read 2.67V)
Pin 5 should read 0.67V, actually 2.67V (marginally below pins 6 and 7, which read 2.69V)

IC10
Pin 3 should read 5.83V, actually 6.94V (same as pins 1 and 2)
Pin 5 should read 4.21V, actually 6.93V (marginally below pins 6 and 7, which read 6.95V)

I'm going through checking component placements but if anything shouts out as an obvious error, I'd appreciate the help!
--
73 Bob G3YIQ


Just finished the clock kit #clock

Jim Sheldon
 

Got my clock kit in the mail yesterday - package was extremely mangled - very poor handling by postal workers somewhere!  Lucky though, the way Hans' crew packages things, nothing inside the mangled box was damaged at all.  Took about an hour to assemble the clock board, and about another hour to get things mounted (including a QLG1 GPS that I have had for a year or so now (used to calibrate several QCX builds).

Looking through the website's picture gallery, I really liked the way VE7TK packaged his with the 4 line display in the air-tight freezer container so I bought one and put my clock/GPS in it.  I had several 4 X 20 blue displays on hand from other projects so I used one of them.  I really like the larger format.  I did remote the programming switches to the front panel and boy was that a help during the tedious programming.

Programming the thing took several hours to read and figure out just how the commands affected things, but I finally got the display I want (at least until Hans fixes the Local date problem in the firmware and I buy a new chip from him.)

With the extreme sensitivity of the QLG1, it locked onto enough satellites to set the date/time within a couple of minutes even sitting on my desk with the built-in "patch" antenna. 

This is going to be a very welcome addition to the shack and if the US Government shuts down WWV/WWVB/WWVH like they have been talking about doing, I'll still have extremely accurate time in the shack.  (I also have a nice, fairly inexpensive GPS Disciplined Sine Wave Oscillator I got for just under $90 US on eBay.  It's also sensitive enough to pick up enough satellites to get a good lock with the antenna inside the house.  My Spectrum analyzer has an external 10 MHz input so I keep the GPSDO on it for accuracy.

Pix of my build (Programmed a little different than VE7TK's).

Jim Sheldon, W0EB
Park City, KS, USA


2m lpf inductors

M0RON
 

Hi all,
I have a question re L2 on the 2m lpf.
All other lpf's have the value of L2 higher than L1,L3, in the 2m lpf page Tor, SM6FWF states that his L2 is a smaller value than L1,L3 but does not give values, should L2 for 2m be higher than L1,L3?
I think it should be higher.
Andy
--
The universe is made up of Protons, Neutrons, Electrons but contains only one M0RON.


Re: T1 winding, how tight? #qcx #t1

Richard Clemens
 

You can also sharpen a dowel in a pencil sharpener to assist with the winding.


Re: 5 volt supply QCX #supply

tk5ep
 

A lot of things can go wrong and produce your problem...

Check for a solder bridge somewhere first.
If nothing found check for a reversed component (polarized capacitor, transistor, IC)

73 Patrick


Re: #wspr U3S for 2m WSPR: How to remove the frequency-swing at start of transmission #wspr

HF
 

Hi Alan
Thanks for calling my attention to the Taitien TCXO.  I ordered a couple.  I'll report here on whether they work better than the Fox 924B in my 2m U3S.
-Halden NR7V


Re: QCX output dropped from 5 W to 4W

tk5ep
 

Hi Peter,

Thanks for the advice. How much power did you have with a broken BS170 ?
Will check on monday.

I read the manual again and section 7.3 it is adviced not to produce more than 5 W and no to supply over 15-16 V. So i was considerabily below.

From tables i see that @ 13.5 V (with reverse protection diode bypassed) the "normal" output power is 4W, so i'm good.

But the question is why did the power drop ?

73, Patrick.


Very Low Power Out #qcx #problem

nigelspear@...
 

Hi

Just finished building the QCX (40m). Recieve works beautifully but I have very low power on transmit - about 20mW
My suspicion is IC3, but before I rip it out an replace it, Id thought Id check to see if there could be any causes.
Ive followed the troubleshooting guide posted by Hans and checked the the expected voltages on IC3 with a DVM.

  1. They are all correct on receive
  2. On transmit. Pins 1 and 2 are correct (around 4.2V) but pin 3 is only at 0.5v. Pin11 is at 1.0v (incorrect) and 12&13 are at 0v
  3. This would explain why the FETs are hardly being driven
  4. Also pins 8 and 9 seem wrong 1.0v and 2.5v
Ive checked for any problems around Q7, but the board is clean with no bridges.
L4 is also delivering a health 12 volts to the BS170's

Any other ideas before I attempt open heart surgery?


Re: Trouble with Blocks on top row of LCD #problem #qcx

Alan G4ZFQ
 

I've verified the processor is inserted correctly, correctly oriented, and that the pins are connecting correctly.  I've verified that the processor is getting power.  I've verified that the crystals are oscillating.
Chris,

There were some that got through without the chip being programmed.
If you are sure all is good then Hans will help, if he does not catch up with the posts write direct.

73 Alan G4ZFQ


Re: QCX output dropped from 5 W to 4W

Peter
 

Check for current drain. I had the same, current rised and the power dropped. One of BS170 was down, replaced with 3 new from other source and the power is now well over 5W at 7MHz. 


Re: Trouble with Blocks on top row of LCD #problem #qcx

s.qrplabs@...
 

Thank you for the suggestion!  Unfortunately when I listen to it, I'm just hearing a consistent hum.  I tried  going through the tuning process, and even tried moving through the menus based on some youtube videos and couldn't hear any evidence of life.  I did go over the LCD solder joints for fun, but unfortunately no luck.

Thanks!

Chris


Re: #wspr U3S for 2m WSPR: How to remove the frequency-swing at start of transmission #wspr

Alan G4ZFQ
 

Henning

These are 26MHz ones I tested and use https://www.ebay.co.uk/itm/CRYSTAL-TCXO-26MHZ-SMD-MPN-X1G0042110002-EPSON-/391339155043?hash=item5b1da19e63:g:1MMAAOSw-nZTpJCO

And mentioned in this thread a 27MHz one from Digikey https://ka7oei.blogspot.com/2018/02/better-frequency-stability-for-qrp-labs.html here the Taiten was said by the author to have no perceivable steps at 432MHz.

Now the same on 2m:
The "chirp" is visable and in addition another effect. There is a ~30Hz
difference between parking-carrier and wspr-modulated carrier. Who can
explain this behaviour ?
All I can think of is that there is a voltage variation, maybe minute, difficult or impossible to see. I think any temperature variations would be slower.
It has been mentioned that the LM317 regulator on the Synth board is run outside its specification for dropout voltage. I would try a low-drop 3.3V regulator. Maybe try a separate 5V supply first.

ps: I recognized your 60m "double"-transmission this night :-)
You mean both main frequencies? Maybe one day there will be just one..... 2 Softrocks, sometimes TX together, sometimes not.

73 Allan G4ZFQ


Re: #wspr U3S for 2m WSPR: How to remove the frequency-swing at start of transmission #wspr

mrdynalink <server@...>
 

@Alan,
ok  ... I like to experiment :-)   Which txco you would recommend to check ?

ps: I recognized your 60m "double"-transmission this night :-)

@All

Here another observation I made while testing park-modes. This is Parkmode 0, Calibration 10s, Tx every 4min  on the 80m-Band:



It`s starting with 10s calibration, then the parking-carrier, then the wspr transmission ... looks perfect.

Now the same on 2m:



The "chirp" is visable and in addition another effect. There is a ~30Hz difference between parking-carrier and wspr-modulated carrier. Who can explain this behaviour ?

Hmm ... my u3s is GPS controlled. Which carrier is the correct one ?

73, Henning


Re: Trouble with Blocks on top row of LCD #problem #qcx

Karl Heinz Kremer - K5KHK
 

This may not fix your problem, but in my recent build, I ran into the same problem. I was able to verify that the receiver worked by listening on some ear buds while tuning. Even without an antenna, you will find some birdies. That confirmed that the processor was actually working, and that the problem must be in the connection to the display. I redid all the solder joints and that fixed it. I am pretty confident that the culprit was one (or more) connection on the LCD board to the connector. 
--
Karl Heinz - K5KHK


Re: #wspr U3S for 2m WSPR: How to remove the frequency-swing at start of transmission #wspr

Alan G4ZFQ
 

I will skip experiments with an tcxo.
Henning

Do not forget you have been given links to cheap TCXOs that have analogue control.
In my experience such a TCXO has been better than my OCXO although I admit I probably gave up to soon with my attempts to optimise it.

73 Alan G4ZFQ


Re: #wspr U3S for 2m WSPR: How to remove the frequency-swing at start of transmission #wspr

mrdynalink <server@...>
 

@Halden: Thank you for telling me your experiences, I will skip experiments with an tcxo. I believe, I already saw your described discrete frequency jumps in the past. Before I tried the U3s I already checked the U02-DDS-Synthesizer. There a 25 MHz txco from Farnell is used. I remember that I was wondering about the asynchronous frequency jumps on 2m-Band ... may be the same problem.

@Glen: Thank you for the hints. Meanwhile I cancelled the plan to use the standard synthesizer and I ordered 2 OCXO for experimenting :-)

@Andy: I`m looking forward to seeing the results of your new 2m U3S ! When I`m ready with my OCXO I will report. Hope this is soon, I'm excited  :-)

73, Henning