Date   

Re: #20m #qsx #rcvr partial short to gnd #20m #qsx #rcvr

Ronald Taylor
 

Syd, it looks to me like you've done all the right things so far. As you say, the problem at this point can either be a shorted trace or IC3 itself. From the photo, the traces look good. Also no solder shorts appear to exist. And that "RX" line doesn't go anywhere else on the board, so I think you should consider removing IC3. I have had to replace this chip on a couple of different repairs. One time it was the source of a low resistance short similar to what you are seeing. If you have some good solder wick and liquid flux it makes the job bearable. Take care not to use more heat than necessary to clear the holes of solder. Good luck ...73 ... Ron


On Fri, Aug 14, 2020 at 10:01 AM N3MNT <bob@...> wrote:
Short could be other places.  Please add photo of rest of board. 


Re: #20m #qsx #rcvr partial short to gnd #20m #qsx #rcvr

N3MNT
 

Short could be other places.  Please add photo of rest of board. 


Re: U3S Latest Firmware has no .eep #smoked #firmware #u3s

umakanth bojanapalli <Bojanapalliumakanth@...>
 

Sir in the files section I found difficult to find the hex file for frimware 3.12a, will you please help me in this regard


QCX 50W amp / PTT cable

Rick Thorpe KC3PNM
 

II had finally got my 40m amp up and running earlier this week.  However, it now is not functioning.  I have re-run the adjustment, which works - amp recognizes the key closing in practice mode on the QCX+, roughly 108 ma of current before turning the screw further results in an increase.  When I reconnect the power without the DVM in the circuit and turn off practice mode, closing the key results in a brief jagged tone and then nothing, no volts out to the dummy load.  QCX+ works fine on its own.

Other than moving things around on the desk, the only change from earlier in the week was to clean up the connection on the stereo cable between the two PTTs.  I have confirmed continuity rig tip to amp ring and sleeve to sleeve.  The remaining wires on each are not connected.   I would have thought that if the issue was in the cord, the alignment wouldn't have worked, so I am not sure where to start with troubleshooting this (other than to examine my soldering for the umpteenth time...)


#20m #qsx #rcvr partial short to gnd #20m #qsx #rcvr

Syd
 


IC2 pin 14, IC3 pins 12&13, and Q5 gate  are all connected together, and this line also measures 18 ohms to ground!  A big problem! I meticulously, with a magnifier, looked at all the pathways and can see no shorts or bad solder joints. I must have done this about 20 times, over and over again. Took out IC2, same results. Tracing the path starting at IC2  pin 14, the path goes to the other end of the IC and then changes side.  Unfortunately I can't see the path on the other side because of the  IC socket.

If I could find a thin enough wire to fit through the through the PCB holes, I would stick a wire through so I could see where the trace continues on the other side and then follow the trace onward. I don't even know if such a thin wire exists and I certainly can't find anything like this size in my junk box. Even unwrapping a stranded wire and using one strand is way too large to fit through the hole. 

Shorts can be a real pain to diagnose. In the 'old days' when PCB paths were a lot larger, I fixed this kind of problem very easily.  I just found the connected paths causing the problem, and then, with a razor blade, make a small cut in one path and found out which branch had the problem. Repeat the process until problem found. Found the problem, fixed it, and then put a solder blob or a jumper wire over the trace and all was well. With today's microscopic PCB paths it seems all we can do is a visual inspection and hope we can find the problem.

I'm at the end of my patience with the problem and will start cutting traces, since the alternative is to take out Q5 and IC3 (destructive) and hope that fixes the problem. I don't like blaming components unless I can prove they are bad. I do hope I can find parts of traces that look like I can do this and then solder blob it back together.

I wonder if anyone else has had similar problems trying to trace shorts in these microscopic PCBs and what they did to solve the issue?  Other than look, look, look.

Attached is a HD picture that can be opened and perused. Note the yellow markers for the 'other side' traces and the note about the wire that I tacked onto pin 14 for troubleshooting purposes.  The picture is only for the area under  concern.

Also note I have removed IC2 and Q5, no help.

wt1v


Re: What to do?

Shirley Dulcey KE1L
 

One thing you can do without warming up the soldering iron is to adjust the spacing of the turns on the inductors in the low pass filters. Squeezing them together reduces inductance; spreading them increases it. What you need is most likely a reduction, so try squeezing them; on a 20m QCX there is plenty of room on the cores to allow you to try that.


On Fri, Aug 14, 2020 at 11:51 AM geoff M0ORE via groups.io <m0ore=tiscali.co.uk@groups.io> wrote:

2 Watts to 3.5 Watts, less than 3dB or less than half a S point. It's not worth the effort of heating the soldering iron. Just make a note in the log book and check again in a couple of months to look for any change.

On 14/08/2020 16:33, Phil/K3UT (ex W3HZZ) wrote:
Last weekend, I completed my build of my third QCX, a 20m QCX+. I powered it up while a European contest was in its Sunday afternoon winddown phase and EU stations were listening for anyone. I promptly worked UA, OZ, HB contacts. Over the next couple of days, I worked US and EU stations - not all, to be sure, but enough.

Before I screwed up the case, I decided to check the power output. With an Elecraft wattmeter, I got about 2 watts with a 13.5 volt PS. With a Digital voltmeter across a dummy load, about 8.3 volts. So, I am below specs. I've checked the number of turns on L1-L2-L3. They're okay. I can count and wind to 17. My guess would be to pull them and take off a wind.

My dilemma - do I leave well enough alone - after all it works. 

Or should I dig inside, and risk all kinds of builder caused catastrophes - burning a trace, messing up the plating around the toroid holes, burning something else with a wayward solder iron- just to get another 1.5 or so watts out of the transceiver?

What would you do?

Phil, K3UT


Re: What to do?

geoff M0ORE
 

2 Watts to 3.5 Watts, less than 3dB or less than half a S point. It's not worth the effort of heating the soldering iron. Just make a note in the log book and check again in a couple of months to look for any change.

On 14/08/2020 16:33, Phil/K3UT (ex W3HZZ) wrote:
Last weekend, I completed my build of my third QCX, a 20m QCX+. I powered it up while a European contest was in its Sunday afternoon winddown phase and EU stations were listening for anyone. I promptly worked UA, OZ, HB contacts. Over the next couple of days, I worked US and EU stations - not all, to be sure, but enough.

Before I screwed up the case, I decided to check the power output. With an Elecraft wattmeter, I got about 2 watts with a 13.5 volt PS. With a Digital voltmeter across a dummy load, about 8.3 volts. So, I am below specs. I've checked the number of turns on L1-L2-L3. They're okay. I can count and wind to 17. My guess would be to pull them and take off a wind.

My dilemma - do I leave well enough alone - after all it works. 

Or should I dig inside, and risk all kinds of builder caused catastrophes - burning a trace, messing up the plating around the toroid holes, burning something else with a wayward solder iron- just to get another 1.5 or so watts out of the transceiver?

What would you do?

Phil, K3UT


Re: What to do?

George Korper
 

I'd  leave it. Formally I would have gone nuts. But look what you did as is! Real QRP and it's  all up from now on sunspot wise.


On Fri, Aug 14, 2020, 10:34 AM Phil/K3UT (ex W3HZZ) <pgraitcer@...> wrote:
Last weekend, I completed my build of my third QCX, a 20m QCX+. I powered it up while a European contest was in its Sunday afternoon winddown phase and EU stations were listening for anyone. I promptly worked UA, OZ, HB contacts. Over the next couple of days, I worked US and EU stations - not all, to be sure, but enough.

Before I screwed up the case, I decided to check the power output. With an Elecraft wattmeter, I got about 2 watts with a 13.5 volt PS. With a Digital voltmeter across a dummy load, about 8.3 volts. So, I am below specs. I've checked the number of turns on L1-L2-L3. They're okay. I can count and wind to 17. My guess would be to pull them and take off a wind.

My dilemma - do I leave well enough alone - after all it works. 

Or should I dig inside, and risk all kinds of builder caused catastrophes - burning a trace, messing up the plating around the toroid holes, burning something else with a wayward solder iron- just to get another 1.5 or so watts out of the transceiver?

What would you do?

Phil, K3UT


Re: Need wspr transmitter source code and latest hex file for frimware 3.12a

geoff M0ORE
 

It is on the QRPLabs groups.io website under files page 2. It also has a PDF on how to upgrade.

On 14/08/2020 14:02, umakanth bojanapalli wrote:
Hi 
My call sign is VU3UBU, recently I am doing Wspr project, in this regard I found difficult in downloading the source code and latest hex file for my hardware frimware version 3.12a

So please kindly send me those codes
 Thank you
Regards Bojanapalli Umakanth


What to do?

Phil/K3UT (ex W3HZZ)
 

Last weekend, I completed my build of my third QCX, a 20m QCX+. I powered it up while a European contest was in its Sunday afternoon winddown phase and EU stations were listening for anyone. I promptly worked UA, OZ, HB contacts. Over the next couple of days, I worked US and EU stations - not all, to be sure, but enough.

Before I screwed up the case, I decided to check the power output. With an Elecraft wattmeter, I got about 2 watts with a 13.5 volt PS. With a Digital voltmeter across a dummy load, about 8.3 volts. So, I am below specs. I've checked the number of turns on L1-L2-L3. They're okay. I can count and wind to 17. My guess would be to pull them and take off a wind.

My dilemma - do I leave well enough alone - after all it works. 

Or should I dig inside, and risk all kinds of builder caused catastrophes - burning a trace, messing up the plating around the toroid holes, burning something else with a wayward solder iron- just to get another 1.5 or so watts out of the transceiver?

What would you do?

Phil, K3UT


Need wspr transmitter source code and latest hex file for frimware 3.12a

Bojanapalliumakanth@...
 

Hi 
My call sign is VU3UBU, recently I am doing Wspr project, in this regard I found difficult in downloading the source code and latest hex file for my hardware frimware version 3.12a

So please kindly send me those codes
 Thank you
Regards Bojanapalli Umakanth


Re: AGC request

@CurtisM
 

Ari
 
Well if you examine the qcx design, only 2 logical places to implement agc, so you yourself can explore it. With the ubitx I wanted to squash huge signals, and it works decently to place a simple led/photoresistor advocated by vk3ye. On qcx it works wonderful without agc. Respect the maestro has a business to run, maybe time to qrt as he is committed to board translation as is. A pair of these in some enclosure arrangement might serve trail ops with a band for each ear in a handheld rig.

73 curt


Re: #qcx #qcx

geoff M0ORE
 

Try page 149, lower left corner, you will see T1. The winding associated with C1, C5 & C8 has one end connected to GND. The winding associated with Q5 source also has one end connected to GND. Due to the low resistance of the windings, you will see continuity between all connections associated with these windings.

On 14/08/2020 05:52, jay@... wrote:
I've gotten my 40m QCX+ and have gotten the T1 toroid wound and installed, but have a question about continuity before I proceed... All of the pairs of pads/holes have continuity, which is good, but the Primary winding (holes 3-4) also seems to have continuity with the Secondary 2 winding (holes 1-2, the big one). Is that right? I don't see a way I could possibly have gotten something twisted or crossed in a way that they would be connected since they aren't next to each other on the toroid.

I've found someone who mentioned this in this thread:
The only thing I have not chased down is the middle 5 wrap secondary is showing a no ohm relationship with the primary. "Shorted to" but have not examined the schematic close enough to know if that is normal path between them through the circuit somewhere. No continuity between the other two secondaries and the primary.
But it isn't confirmed that it's expected, so I just wanted to double check here.

Jay K, KG4FUU


Re: Change request, add morse characters #firmware #qcx

Ben
 

From some things I've read, techinically CQ is a prosign as per ITU-R M.1172
Is it? It doesn't have the line above the letters like BT for example.

BK is a prosign defined by ITU-R M.1172
Same as above, it is in the list of abbreviations, but doesn't have the line run above the letters.

So regarding M.1172 (for the maritime mobile service) they are not run together. But i learned BK run together to signal a quick over (without call signs).


#qcx #qcx

jay@...
 

I've gotten my 40m QCX+ and have gotten the T1 toroid wound and installed, but have a question about continuity before I proceed... All of the pairs of pads/holes have continuity, which is good, but the Primary winding (holes 3-4) also seems to have continuity with the Secondary 2 winding (holes 1-2, the big one). Is that right? I don't see a way I could possibly have gotten something twisted or crossed in a way that they would be connected since they aren't next to each other on the toroid.

I've found someone who mentioned this in this thread:
The only thing I have not chased down is the middle 5 wrap secondary is showing a no ohm relationship with the primary. "Shorted to" but have not examined the schematic close enough to know if that is normal path between them through the circuit somewhere. No continuity between the other two secondaries and the primary.
But it isn't confirmed that it's expected, so I just wanted to double check here.

Jay K, KG4FUU


Re: Change request, add morse characters #firmware #qcx

Ben
 

For what it's worth, I checked 3 devices with a display.

Elecraft KX2: SK
K3NG keyer: SK
Morserino 32: <SK>

Ben,
PA2ST


Re: QCX Firmware change request: Validate CAT frequency values. #qcx #firmware #cat

Ham Radio
 

Note that there is a bug in Rev T1.05 where if you send a CAT CW speed command, the display sometimes  gets corrupted and I believe there may be  another issue — I just don’t remember.

Hans is aware of the issue.  For now, make sure your host software does not send the CW speed command to the QCX.


--
73, Bernie, VE3FWF
(most typos in this message have been generated by highly sophisticated auto-correction software)


Re: Difficulty during alignment - RF output #20m #qcx #problem

Ronald Taylor
 

Alan made a great point about the possibility of open circuit BS-170s. Since you are paying shipping costs, you should probably order a handful of those as well. It looks like they are functioning somewhat from the explanation you gave but if the lowpass filter indeed tests good, then there should be power output, even though there is constant DC (not keyed on and off) at the drains. So remove the Q1, Q2, Q3 and Q6 while waiting for the parts to arrive. Install the new Q6 first. Check on the empty drain pad of Q1 (pin 1 in your drawing) for DC only when key is pressed. Also check on the empty gate pad (pin 2 in your drawing) for 2.5 V when the key is pressed. If both of those are correct, install Q1, Q2 and Q3 and test. 

Ron


Re: Difficulty during alignment - RF output #20m #qcx #problem

W5EGA@...
 

Sorry - work has been hectic these past few days and I'm just getting around to looking at this again.

Ok, I have checked continuity between the center BNC pin and end of C29 and it is good. So, I guess that just leaves Q6. Is there anything else that I should check that could be causing my issues? I will order a new Q6 tonight. 

Thanks! 


Re: AGC request

Daniel Walter
 

Boy, I'd love to have an AGC, an SWR foldback circuit, an antenna tuner, ... etc. It's called a KX3, which is a wonderful radio. However it's 20-30 times as expensive. I for one , applaud Hans approach. He has given us a wonderful transceiver at a fantastic price. He's also listened to lots of our requests and implemented many of them. However, there's a limit to what can be done. Let's see what we get with the next level that Hans comes up with. 
--
73, Dan  NM3A