Topics

QCX 40 meter build help, 700 HZ tone shows up in weird place... #40m #si5351a

Mark Garrisi
 

Hi everyone!

      Thank you for the add.  I'm really excited about building my 40 meter QCX I ordered.  Got a problem that is perplexing me and I want to pose to the group.

I'm troubleshooting on why I do not have a 700 hz tone when I go to 8.7 BPF Alignment.  So I'm using a cheap DSO 150 scope and start tracing as by Han's troubleshooting video.  
Here is the weird part, Start 8.7 BPF alignment, plug in headphones,  I start at the source for the tone output, IC1 pin 6, I touch it with the probe - Tone comes on through earphones and my display jumps up to 10 and allows me to peak it at 11.  I remove the probe from the pin, it all stops and my display goes down to 3, no audio.

Has anyone out here come across this?  Of course, I've checked my solder joints and values of components.  All my IC's show correct voltages but no 700 hz tone on the pins.

I sincerely ask for any suggestions and thoughts on what I can do.  I know I'm so close to getting this on the air. Not to mention the cabinet I've been building for it.

Thanks for reading.

Mark

Alan G4ZFQ
 

Has anyone out here come across this?  Of course, I've checked my solder joints
Mark,

Sorry, that seems just like a bad joint.
What about IC3 pin 4?
If nothing looks like it is IC1 pin 6 that's bad. Not easy, look carefully round that connection.
Try to resolder, desolder braid gets rid of any excess.

73 Alan G4ZFQ

Wes AE6ZM
 

It seems you may have misunderstood the function of the various components.
First, IC1 does not produce any 700 hz tone. It operates at the RF frequency you have set. For a 40 M QCX, this will be in the 7 MHz range. IC1 pin 6 is the actual transmit frequency source, which is routed to IC3 which routes it our either pin 3 during transmit, or pin 8 during alignment. If you are getting a tune signal when you have the probe on IC1-6 but not when on IC3-8 it means the gate IC3C is not turning on. The strange behavior you are seeing when touching pin IC1-6 is just the RF signal being radiated into the T1 circuit and going thru the Quadrature and audio circuits, as it should. The 700 hz tone is created in the Quad circuit, not produced by some oscillator. 
Second, where you want to look is at IC3 pin 9 to see if the voltage changes when in Tune or in TX/RX. That pin is the control pin for the IC3C gate. 
Third, if you hear/see the 700HZ tone when you probe IC3 pin 8 it means that the RF signal is going thru IC3C gate, but is not getting to the antenna connector and back to the T1 circuit. Check continuity of R43 and back to C29. Your problem could be anywhere in that circuit, including Q5. 
--
> I finally got it all together...now I can't remember where I put it<

VY 73,
Wes

AE6ZM

Sierra Vista, AZ

 

Mark Garrisi
 

Makes perfect sense.  I’ll look at it tonight and inspect the area.

Thank you, Wes. I’ll update soon...


On Jun 6, 2020, at 11:49 AM, Wes AE6ZM <wesbflyer@...> wrote:

It seems you may have misunderstood the function of the various components.
First, IC1 does not produce any 700 hz tone. It operates at the RF frequency you have set. For a 40 M QCX, this will be in the 7 MHz range. IC1 pin 6 is the actual transmit frequency source, which is routed to IC3 which routes it our either pin 3 during transmit, or pin 8 during alignment. If you are getting a tune signal when you have the probe on IC1-6 but not when on IC3-8 it means the gate IC3C is not turning on. The strange behavior you are seeing when touching pin IC1-6 is just the RF signal being radiated into the T1 circuit and going thru the Quadrature and audio circuits, as it should. The 700 hz tone is created in the Quad circuit, not produced by some oscillator. 
Second, where you want to look is at IC3 pin 9 to see if the voltage changes when in Tune or in TX/RX. That pin is the control pin for the IC3C gate. 
Third, if you hear/see the 700HZ tone when you probe IC3 pin 8 it means that the RF signal is going thru IC3C gate, but is not getting to the antenna connector and back to the T1 circuit. Check continuity of R43 and back to C29. Your problem could be anywhere in that circuit, including Q5. 
--
> I finally got it all together...now I can't remember where I put it<

VY 73,
Wes

AE6ZM

Sierra Vista, AZ

 

James Daldry W4JED
 

Hi, Mark

I would start by taking a fine solder pencil tip and reflowing the connections on IC1. It wouldn't be the first time I saw a leg on an SMD chip hanging a couple of thou above the foil, making like a tiny microswitch CW key.

73

Jim W4JED

On 6/5/20 10:50 PM, n8iaj via groups.io wrote:
Hi everyone!

      Thank you for the add.  I'm really excited about building my 40 meter QCX I ordered.  Got a problem that is perplexing me and I want to pose to the group.

I'm troubleshooting on why I do not have a 700 hz tone when I go to 8.7 BPF Alignment.  So I'm using a cheap DSO 150 scope and start tracing as by Han's troubleshooting video.  
Here is the weird part, Start 8.7 BPF alignment, plug in headphones,  I start at the source for the tone output, IC1 pin 6, I touch it with the probe - Tone comes on through earphones and my display jumps up to 10 and allows me to peak it at 11.  I remove the probe from the pin, it all stops and my display goes down to 3, no audio.

Has anyone out here come across this?  Of course, I've checked my solder joints and values of components.  All my IC's show correct voltages but no 700 hz tone on the pins.

I sincerely ask for any suggestions and thoughts on what I can do.  I know I'm so close to getting this on the air. Not to mention the cabinet I've been building for it.

Thanks for reading.

Mark

Wes AE6ZM
 

Jim, that sure does happen. Personally I would make a first step to see what signal is present along the IC1-6 to IC3C trace. If the Tune signal shows up when touching a probe to points along this trace, then the problem is not IC1. Reflowing a tiny SMD device like IC1 has its own world of problematic consequences. That would not be my recommended first step. 

--
> I finally got it all together...now I can't remember where I put it<

VY 73,
Wes

AE6ZM

Sierra Vista, AZ

 

Mark Garrisi
 

I checked continuity between R43 through C29 and it's good.  De-soldered IC3 carefully with braid and resoldered.  I do have an .69 watt output, but have 5.2 watts showing  at C29.  I'm tired now, 1 am in Detroit.  I'll tackle more tomorrow, I'll do more work in the LPF chain.  Still have same problem.  Yes, I do have tone at pin 8 when I touch it with probe.  Will update as I go.
Tnx Wes.  

James Daldry W4JED
 

Hi, Mark

If you have 5.2 watts showing at the 3 output FET's and 0.69 into a KNOWN GOOD 50 OHM DUMMY LOAD at the antenna jack, I would check for (1) continuity from C21 to the center pin of the antenna jack and (2) resistance from the antenna jack center pin to ground. There should be zero ohms from C29 to the antenna jack and infinite ohms from the jack center to ground.

73

Jim W4JED

On 6/7/20 1:08 AM, Mark Garrisi via groups.io wrote:
I checked continuity between R43 through C29 and it's good.  De-soldered IC3 carefully with braid and resoldered.  I do have an .69 watt output, but have 5.2 watts showing  at C29.  I'm tired now, 1 am in Detroit.  I'll tackle more tomorrow, I'll do more work in the LPF chain.  Still have same problem.  Yes, I do have tone at pin 8 when I touch it with probe.  Will update as I go.
Tnx Wes.  

Mark Garrisi
 

Hi James;

     I've check C29 to center pin on antenna jack, and yes, full continuity.  1380 Ohms from pin to ground, 1.5 ohms from center pin to board pin.  I'm almost calling it quits...

James Daldry W4JED
 

Hi, Mark

1380 ohms? Something is leaky, and that something won't act like a capacitor. Most likely one of the low pass filter caps is punctured and that is allowing the RF to arc to ground. If I was troubleshooting it I would unhook one filter coil lead at a time until I determined which capacitor had the problem. The coils can easily be unsoldered one end at a time. Not so much the caps. Safe (not tearing up the board) removal of a small ceramic cap pretty much requires crushing the cap with pliers, then desoldering the leads 1 at a time. Have fun.

73

Jim W4JED

On 6/8/20 12:40 PM, Mark Garrisi via groups.io wrote:
Hi James;

     I've check C29 to center pin on antenna jack, and yes, full continuity.  1380 Ohms from pin to ground, 1.5 ohms from center pin to board pin.  I'm almost calling it quits...

Mark Garrisi
 

To Everyone;

     I'm reporting back that I had a another ham look at my rig for a fresh set of eyes. Come to find out, I skipped a step in 1nF caps installation.

Sometimes when a second person looks at a situation, a solution may present itself.  I did here.  I humbly take this as a lesson learned.  This is why I love Amateur Radio, hams helping hams, like all of you when I asked for help.  Radio TX @ 5 watts at 13.6 volts & receive and alignment is great.  I'm in the process of final assembly of the casing and will post pics here if I can.  Thank you to Wes, James, & Alan!

See you on the air soon,

Mark N8IAJ

James Daldry W4JED
 

Hi, Folks

Back in the late '80's I was working on a VCR with no color on playback. I had already replaced the chip that had the playback chroma in it, without correcting the problem. The other bench tech walked over and said "Whatcha workin on?" I told him. He said "Did you see that corner?" A triangular piece was broken off the main PCB, interrupting one foil path. Guess what? It was the playback chroma.

Second set of eyes.

Jim W4JED

On 6/12/20 1:54 PM, Mark Garrisi via groups.io wrote:
To Everyone;

     I'm reporting back that I had a another ham look at my rig for a fresh set of eyes. Come to find out, I skipped a step in 1nF caps installation.

Sometimes when a second person looks at a situation, a solution may present itself.  I did here.  I humbly take this as a lesson learned.  This is why I love Amateur Radio, hams helping hams, like all of you when I asked for help.  Radio TX @ 5 watts at 13.6 volts & receive and alignment is great.  I'm in the process of final assembly of the casing and will post pics here if I can.  Thank you to Wes, James, & Alan!

See you on the air soon,

Mark N8IAJ

jjpurdum
 

Same principle applies to software, too. I fiddled with a bug for almost a full day and got nowhere. Asked Al (AC8GY) if he had any ideas. 15 seconds later, the bug died. Took me about a week to scrap the egg off my face...

Jack, W8TEE

On Friday, June 12, 2020, 3:09:30 PM EDT, James Daldry W4JED <jim@...> wrote:


Hi, Folks

Back in the late '80's I was working on a VCR with no color on playback. I had already replaced the chip that had the playback chroma in it, without correcting the problem. The other bench tech walked over and said "Whatcha workin on?" I told him. He said "Did you see that corner?" A triangular piece was broken off the main PCB, interrupting one foil path. Guess what? It was the playback chroma.

Second set of eyes.

Jim W4JED

On 6/12/20 1:54 PM, Mark Garrisi via groups.io wrote:
To Everyone;

     I'm reporting back that I had a another ham look at my rig for a fresh set of eyes. Come to find out, I skipped a step in 1nF caps installation.

Sometimes when a second person looks at a situation, a solution may present itself.  I did here.  I humbly take this as a lesson learned.  This is why I love Amateur Radio, hams helping hams, like all of you when I asked for help.  Radio TX @ 5 watts at 13.6 volts & receive and alignment is great.  I'm in the process of final assembly of the casing and will post pics here if I can.  Thank you to Wes, James, & Alan!

See you on the air soon,

Mark N8IAJ

 

Good story, Jim.

I have one that's about one.single.dot...

Back in the mid 90's I was in my first software software damagement position. A fellow working on a project for me was writing some code in 8086 assembly language (don't ask). He'd been fighting a behavior problem (in the code, that is) for a good two days. Finally he calls me over and shows me the listing. "It's in here, in these three lines, I KNOW IT!" he insisted "But I just can't see it!".

He was more correct than he knew: the dot matrix printer he had used to  print out his source code had a sticky pin, and didn't correctly print out the midle bar of an "E", making it look like a "C". He had mistaken a "JNE" ("Jump on not equal") instruction for a "JNC" ("Jump on no carry "). When I pointed out the fact that lots of characters in the printout had dots missing, and that he had been subconciously correcting them, he darn near exploded :-)

The whole discovery took no more than a minute.

Second pair of eyes :-)

Julian, N4JO.

On 6/12/2020 2:09 PM, James Daldry W4JED wrote:

Hi, Folks

Back in the late '80's I was working on a VCR with no color on playback. I had already replaced the chip that had the playback chroma in it, without correcting the problem. The other bench tech walked over and said "Whatcha workin on?" I told him. He said "Did you see that corner?" A triangular piece was broken off the main PCB, interrupting one foil path. Guess what? It was the playback chroma.

Second set of eyes.

Jim W4JED

On 6/12/20 1:54 PM, Mark Garrisi via groups.io wrote:
To Everyone;

     I'm reporting back that I had a another ham look at my rig for a fresh set of eyes. Come to find out, I skipped a step in 1nF caps installation.

Sometimes when a second person looks at a situation, a solution may present itself.  I did here.  I humbly take this as a lesson learned.  This is why I love Amateur Radio, hams helping hams, like all of you when I asked for help.  Radio TX @ 5 watts at 13.6 volts & receive and alignment is great.  I'm in the process of final assembly of the casing and will post pics here if I can.  Thank you to Wes, James, & Alan!

See you on the air soon,

Mark N8IAJ

Mark Garrisi
 



All done!

Love the rig!



On Jun 12, 2020, at 3:13 PM, jjpurdum via groups.io <jjpurdum@...> wrote:


Same principle applies to software, too. I fiddled with a bug for almost a full day and got nowhere. Asked Al (AC8GY) if he had any ideas. 15 seconds later, the bug died. Took me about a week to scrap the egg off my face...

Jack, W8TEE

On Friday, June 12, 2020, 3:09:30 PM EDT, James Daldry W4JED <jim@...> wrote:


Hi, Folks

Back in the late '80's I was working on a VCR with no color on playback. I had already replaced the chip that had the playback chroma in it, without correcting the problem. The other bench tech walked over and said "Whatcha workin on?" I told him. He said "Did you see that corner?" A triangular piece was broken off the main PCB, interrupting one foil path. Guess what? It was the playback chroma.

Second set of eyes.

Jim W4JED

On 6/12/20 1:54 PM, Mark Garrisi via groups.io wrote:
To Everyone;

     I'm reporting back that I had a another ham look at my rig for a fresh set of eyes. Come to find out, I skipped a step in 1nF caps installation.

Sometimes when a second person looks at a situation, a solution may present itself.  I did here.  I humbly take this as a lesson learned.  This is why I love Amateur Radio, hams helping hams, like all of you when I asked for help.  Radio TX @ 5 watts at 13.6 volts & receive and alignment is great.  I'm in the process of final assembly of the casing and will post pics here if I can.  Thank you to Wes, James, & Alan!

See you on the air soon,

Mark N8IAJ

Dave
 

Looks great!  Love to see a picture of the insides as well.

Dave


On Jun 19, 2020, at 09:58, Mark Garrisi via groups.io <n8iaj@...> wrote:


<image0.jpeg>

<image2.jpeg>

All done!

Love the rig!



On Jun 12, 2020, at 3:13 PM, jjpurdum via groups.io <jjpurdum@...> wrote:


Same principle applies to software, too. I fiddled with a bug for almost a full day and got nowhere. Asked Al (AC8GY) if he had any ideas. 15 seconds later, the bug died. Took me about a week to scrap the egg off my face...

Jack, W8TEE

On Friday, June 12, 2020, 3:09:30 PM EDT, James Daldry W4JED <jim@...> wrote:


Hi, Folks

Back in the late '80's I was working on a VCR with no color on playback. I had already replaced the chip that had the playback chroma in it, without correcting the problem. The other bench tech walked over and said "Whatcha workin on?" I told him. He said "Did you see that corner?" A triangular piece was broken off the main PCB, interrupting one foil path. Guess what? It was the playback chroma.

Second set of eyes.

Jim W4JED

On 6/12/20 1:54 PM, Mark Garrisi via groups.io wrote:
To Everyone;

     I'm reporting back that I had a another ham look at my rig for a fresh set of eyes. Come to find out, I skipped a step in 1nF caps installation.

Sometimes when a second person looks at a situation, a solution may present itself.  I did here.  I humbly take this as a lesson learned.  This is why I love Amateur Radio, hams helping hams, like all of you when I asked for help.  Radio TX @ 5 watts at 13.6 volts & receive and alignment is great.  I'm in the process of final assembly of the casing and will post pics here if I can.  Thank you to Wes, James, & Alan!

See you on the air soon,

Mark N8IAJ

Mark Garrisi
 




On Jun 19, 2020, at 10:10 AM, Dave <VE3GSO@...> wrote:

Looks great!  Love to see a picture of the insides as well.

Dave


On Jun 19, 2020, at 09:58, Mark Garrisi via groups.io <n8iaj@...> wrote:


<image0.jpeg>

<image2.jpeg>

All done!

Love the rig!



On Jun 12, 2020, at 3:13 PM, jjpurdum via groups.io <jjpurdum@...> wrote:


Same principle applies to software, too. I fiddled with a bug for almost a full day and got nowhere. Asked Al (AC8GY) if he had any ideas. 15 seconds later, the bug died. Took me about a week to scrap the egg off my face...

Jack, W8TEE

On Friday, June 12, 2020, 3:09:30 PM EDT, James Daldry W4JED <jim@...> wrote:


Hi, Folks

Back in the late '80's I was working on a VCR with no color on playback. I had already replaced the chip that had the playback chroma in it, without correcting the problem. The other bench tech walked over and said "Whatcha workin on?" I told him. He said "Did you see that corner?" A triangular piece was broken off the main PCB, interrupting one foil path. Guess what? It was the playback chroma.

Second set of eyes.

Jim W4JED

On 6/12/20 1:54 PM, Mark Garrisi via groups.io wrote:
To Everyone;

     I'm reporting back that I had a another ham look at my rig for a fresh set of eyes. Come to find out, I skipped a step in 1nF caps installation.

Sometimes when a second person looks at a situation, a solution may present itself.  I did here.  I humbly take this as a lesson learned.  This is why I love Amateur Radio, hams helping hams, like all of you when I asked for help.  Radio TX @ 5 watts at 13.6 volts & receive and alignment is great.  I'm in the process of final assembly of the casing and will post pics here if I can.  Thank you to Wes, James, & Alan!

See you on the air soon,

Mark N8IAJ

Dave
 

Wow!  Thanks.  Love the ribbon cable.  I like using that too.  I didn't see evidence of the fan in the previous shots.  You obviously thought it necessary, or there was a hole in the cabinet that needed filling.  Does it not seriously increase the total current drawn, which is a disadvantage for power by battery.

Dave


On Fri, Jun 19, 2020 at 11:01 AM Mark Garrisi via groups.io <n8iaj=yahoo.com@groups.io> wrote:



On Jun 19, 2020, at 10:10 AM, Dave <VE3GSO@...> wrote:

Looks great!  Love to see a picture of the insides as well.

Dave


On Jun 19, 2020, at 09:58, Mark Garrisi via groups.io <n8iaj=yahoo.com@groups.io> wrote:


<image0.jpeg>

<image2.jpeg>

All done!

Love the rig!



On Jun 12, 2020, at 3:13 PM, jjpurdum via groups.io <jjpurdum=yahoo.com@groups.io> wrote:


Same principle applies to software, too. I fiddled with a bug for almost a full day and got nowhere. Asked Al (AC8GY) if he had any ideas. 15 seconds later, the bug died. Took me about a week to scrap the egg off my face...

Jack, W8TEE

On Friday, June 12, 2020, 3:09:30 PM EDT, James Daldry W4JED <jim@...> wrote:


Hi, Folks

Back in the late '80's I was working on a VCR with no color on playback. I had already replaced the chip that had the playback chroma in it, without correcting the problem. The other bench tech walked over and said "Whatcha workin on?" I told him. He said "Did you see that corner?" A triangular piece was broken off the main PCB, interrupting one foil path. Guess what? It was the playback chroma.

Second set of eyes.

Jim W4JED

On 6/12/20 1:54 PM, Mark Garrisi via groups.io wrote:
To Everyone;

     I'm reporting back that I had a another ham look at my rig for a fresh set of eyes. Come to find out, I skipped a step in 1nF caps installation.

Sometimes when a second person looks at a situation, a solution may present itself.  I did here.  I humbly take this as a lesson learned.  This is why I love Amateur Radio, hams helping hams, like all of you when I asked for help.  Radio TX @ 5 watts at 13.6 volts & receive and alignment is great.  I'm in the process of final assembly of the casing and will post pics here if I can.  Thank you to Wes, James, & Alan!

See you on the air soon,

Mark N8IAJ

Mark Garrisi
 

Not a biggie if I'm running a plug-in power supply.  I will not run WSPR  on a battery, (at least the AA configuration)