Re: Help with strange audio fault

Alan G4ZFQ

Let's throw some logic at the target.
Jim,

Sorry I do not understand what you are trying to prove.
Ted has quoted 5.88 volts at pin 5 0f IC10. Measured with his DVM. This approximately 1/2 the supply voltage which is what one expects from the potential divider.

So - either the +12 volt end of R40 isn't making the trip or the ground end of R39 isn't.
Which would give a big error when measuring pin 5 voltage.

Perhaps you can explain why pin 6 is at 5.36 volts. Where does that come from?

73 Alan G4ZFQ

Re: Help with strange audio fault

Ted 2E0THH

Dear James and Alan

Thank you so much for helping me out here.
I'll be back on the case in about 90 minutes and will report.
James, I am thinking about just trying small wire bridges to isolate which one is open circuit.

73s Ted
M7ECH

Re: Help with strange audio fault

James Daldry W4JED

Hi, guys

Let's throw some logic at the target.

My B&K 2405 meter tells me that when my Fluke 111 is measuring the resistance of a 10K resistor it is putting about 0.115 volts across the resistor. In other words, it's not turning on any semiconductors. Especially silicon ones.

Assuming that the radio draws 100 ma on receive, let's substitute a 1200 ohm resistor for the radio, making a network of 2 10K resistors with a 1200 ohm across the open ends. A triangle. The 1200 ohm resistor takes the place of the rest of the radio. If we put an ohmmeter across one of the 10K resistors, then short the 1200 ohm resistor, we will get about 5300 ohms with the circuit "normal" and 5000 with a short across the 1200. So - either the +12 volt end of R40 isn't making the trip or the ground end of R39 isn't.

Jim Daldry W4JED

On 1/15/19 4:12 AM, Alan G4ZFQ wrote:
Battery disconnected
IC10 p5 to ground = 5.33K
PCB battery terminals shorted
IC10 p5 to ground = 5.33K
Just pondering what that means
Ted,

That means look at pin 6.

73 Alan G4ZFQ

Re: QCX 20m little Watt on output

Ronald Taylor

Patrick, the output of the BS170s is a square wave with lots of harmonics. The low pass filter removes the harmonic energy leaving only the fundamental. It’s normal to see a reduction in measured power after the harmonic parts are removed. I’ve worked on 3 QCX20s and 3.5 watts out is the best I’ve ever obtained. I think all is normal here.

Ron

On Tue, Jan 15, 2019 at 05:33 <hb9fkp@...> wrote:
Hello all
Who can help me?
At 13.5 volts I have just 3.5 watts at the L1 HF-output pin.
The BS170 has 5.2 watts at all three.
The windings are according to the description.
The varnish of the winding wire is all good.
The values are:
1 = 5.2 W
2 = 4.7 W
3 = 4.2 W
4 = 4.7 W
5 = 4.2 W
6 = 2.0 W
7 = 5.2 W
8 = 2.1 W

What could be the problem?
Thank you for your interest and help.
Best 73... Patrick

Re: QCX 20m little Watt on output

Dieter, DH1HD

Hallo Lbr OM Patrick, es ist schon viel darüber geschrieben worden, einfach mal div. Beiträge durchsuchen.
Tatsache ist, das es hier schon mehrere User hier gab, wo die Leistung beim 20 Meter QCX nicht ausreichend war.
Bei meinem 20 M QCX habe ich die Kondensatoren C25,26, 28, 29 sowie den C30 gegen bessere ausgetauscht und es war eine deutliche Leistungssteigerung messbar.
Schau bitte auch mal meine eingestellten Bilder an.

73 de DH1HD, Dieter

-----Ursprüngliche Mitteilung-----
Von: hb9fkp <hb9fkp@...>
An: QRPLabs <QRPLabs@groups.io>
Verschickt: Di, 15. Jan. 2019 13:29
Betreff: [QRPLabs] QCX 20m little Watt on output #problem

Hello all
Who can help me?
At 13.5 volts I have just 3.5 watts at the L1 HF-output pin.
The BS170 has 5.2 watts at all three.
The windings are according to the description.
The varnish of the winding wire is all good.
The values are:
1 = 5.2 W
2 = 4.7 W
3 = 4.2 W
4 = 4.7 W
5 = 4.2 W
6 = 2.0 W
7 = 5.2 W
8 = 2.1 W

What could be the problem?
Thank you for your interest and help.
Best 73... Patrick

Re: QCX 20m little Watt on output

Hans Summers

Hi Patrick

You have NO problem.

The QCX built-in RF power meter, like most peak- or RMS- detecting power meters, will only be accurate if a sine wave is applied. The waveform at the BS170 drains is VERY non-sinusoidal. The display reading 5.2W here is completely meaningless.

The measurement is only meaningful when it is a sine wave which means, at the output of the LPF.

3.5W is not a bad power at 13.8V on 20m.

73 Hans G0UPL

On Tue, Jan 15, 2019, 15:29 <hb9fkp@... wrote:
Hello all
Who can help me?
At 13.5 volts I have just 3.5 watts at the L1 HF-output pin.
The BS170 has 5.2 watts at all three.
The windings are according to the description.
The varnish of the winding wire is all good.
The values are:
1 = 5.2 W
2 = 4.7 W
3 = 4.2 W
4 = 4.7 W
5 = 4.2 W
6 = 2.0 W
7 = 5.2 W
8 = 2.1 W

What could be the problem?
Thank you for your interest and help.
Best 73... Patrick

QCX 20m little Watt on output

hb9fkp@...

Hello all
Who can help me?
At 13.5 volts I have just 3.5 watts at the L1 HF-output pin.
The BS170 has 5.2 watts at all three.
The windings are according to the description.
The varnish of the winding wire is all good.
The values are:
1 = 5.2 W
2 = 4.7 W
3 = 4.2 W
4 = 4.7 W
5 = 4.2 W
6 = 2.0 W
7 = 5.2 W
8 = 2.1 W

What could be the problem?
Thank you for your interest and help.
Best 73... Patrick

2m u3s

M0RON

Hi all,
I've been working on a vhf u3s, 2m produces around 20mW and 6m 50mW's, with standard pa and inductor, this can be increased but the single bs170 gets very hot.
I am going to try a T37-17 20-200mhz as the inductor and a RD15HVF1 as pa. The inductor will be wound as 25 turns single winding and a 10 turns bifalar winding.
I have the OCXO and the output is very stable but 0.02w from my location isn't going to get far, initial reception tests have been promising, my problem is a big lump of a hill to the north and east, about half a mile away which blocks vhf signals.
Has anyone else tried this combination of inductor and pa? I have parts ready to fix to board, I converted a clock kit that I acquired to u3s spec, waiting for a processor and then I can begin experiment. To start with I'm going to use short fly leads to attach pa and inductor to main board enabling me to make changes easily.

--
The universe is made up of Protons, Neutrons, Electrons but contains only one M0RON.

Re: Help with strange audio fault

Alan G4ZFQ

Battery disconnected
IC10 p5 to ground = 5.33K
PCB battery terminals shorted
IC10 p5 to ground = 5.33K
Just pondering what that means
Ted,

That means look at pin 6.

73 Alan G4ZFQ

Re: Help with strange audio fault

Ted 2E0THH

Hi again Alan and James

Battery disconnected
IC10 p5 to ground = 5.33K

PCB battery terminals shorted
IC10 p5 to ground = 5.33K

Just pondering what that means

73s Ted
M7ECH

Re: Help with strange audio fault

Ted 2E0THH

Hi Alan

Just about to get stuck in again and saw yours and James' posts.
Yes the voltages readings were taken under fault conditions with my DVM Fluke (I only have a few seconds window when the set works)
I am pretty certain it is a 10k Alan but will get a camera in there to check. Both ends are soldered and the set performed flawlessly for nearly a month.

I will run James' tests and report back, huge thanks James and Alan (and everyone else on the safety advice),

73s Ted
M7ECH

Re: Help with strange audio fault

Alan G4ZFQ

James wrote:
If it fails these 2 tests you have a connection problem at pin 5.
Ted,

Are your voltage readings taken when the fault is present? If so then surely pin 5 is correct? (James, Ted is using his DVM which is not loading the circuit like Hans' figures show.)
I'm concerned about pin 6 which should be connected to pin 7 by R38, as there should be no other DC connection to pin 6 it should therefore be close to the pin 7 voltage.
Is R38 soldered? Check it's value, that each end is actually connected to the IC pins. Check the resistance from pin 6 to ground.

73 Alan G4ZFQ

Re: Help with strange audio fault

Roger Hill

I think the resistance tests would be done with the battery disconnected...DO NOT intentionally short the battery itself.

Of course the voltage checks would need the battery connected, but at that stage you are not shorting anything.

Roger
G3YTN

Roger

---
***************************
Roger Hill
***************************

On 2019-01-15 02:13, Bill Cromwell wrote:
Ted,
Do not intentionally short the battery terminals out. If you do be
sure to wear adequate eye protection. Have a new fuse on hand and the
present fuse between your crowbar and those battery terminals.
Batteries can and do explode when the terminals are shorted out.
73,
Bill KU8H
On 1/14/19 8:37 PM, James Daldry W4JED wrote:
Hi, Ted
On the top side of the board, check the resistance from pin 5 of IC10 to ground. It should be around 10K. Now short the battery terminals out. It should now be about 5K. If it fails these 2 tests you have a connection problem at pin 5.
If you connect your voltmeter to pin 5 (top side, not bottom) and then connect the battery it will probably start at 5-ish volts and gradually drift upward. That's your 5 seconds of audio. One end of R39 should be zero ohms to battery negative and the other end zero ohms to pin 5 of IC10, measured on the top of the board. I keep stressing "top of the board" because there may be a bad solder joint or an open piece of foil at pin 5. The break may be invisible. It's possible that R39 is open but so unlikely that I would exhaust all other possibilities before changing it out. Oh, the other foil that could have a problem is from R39 to ground.
Jim Daldry W4JED
On 1/14/19 2:01 PM, qrp@runway23.com wrote:
Just a quick update.
I am still struggling to track this fault down but I do now have some data from my latest investigation.
Do note that this QSX40 set aligned perfectly and was working fine for 2 weeks.
The fault is no receiver output. However if I turn it off for an hour, it fires up again for about 5 seconds and then fades out. This is repeatable. If I fire it again instantly, the fault hasn't cleared and stays silent.
I have been around every solder joint with the iron, not very scientific but sometimes it is a quick fix.
So I though I would start at the beginning with a factory reset and realignment.
8.7 Peak BPF worked fine and produced its normal deafening output.
However 8.8 I-Q Bal, 8.9 Phase Lo and 8.10 Phase Hi are all at 0
Given this alignment needs audio from the output stage, this I think is a fairly good pointer.
IC9 Voltages
1) 4.78
2) 4.78
3) 4.45
4) 0
5) 2.44
6) 2.45
7) 2.45
8) 12
And now IC10, these voltages are clearly wrong
1) 11.06
2) 11.06
3) 11.09
4) 0
5) 5.88
6) 5.36
7)11.10
8) 12
I have been over and over the PCB looking for shorts and dry joints around IC10 and IC09 to no avail (that doesn't mean they don't exist)
The weird part is that after leaving the set off, after time it will always fire up for a few seconds before fading away.
I am going to get my supper and then have another bash but any pointers at all would be most gratefully received.
73 Ted M7ECH
On Thu, Jan 10, 2019 at 02:13 PM, <qrp@runway23.com> wrote:
Just before I remove the QCX40 from its enclosure to fault find, I
thought I would share it in case anyone else had ever experienced
a similar issue.
My QCX40 rev4 has been performing beautifully for about a month
now since it was built.
It is installed in a bespoke enclosure with a alternative volume
control with a power switch.
The fault first manifested itself about 2 weeks ago, I had left
the set on all day but when I went to listen out later in the
evening, there was no audible output.
I had some work to complete so I turned it off for a few hours but
when I switched it back on, all perfect again!
It remained fine for about 5 minutes and then it just went quiet
again, not instantly but as though a volume control was being
turned down.
It was now late so I left it overnight with a view to fault find
it in the morning.
Of course in the morning all fine again!
It has been fine until a few days ago when the fault returned.
If I turn it off for an hour, it fires up again fine but then the
gremlin in there turns the audio down after about 20 secs. This is
fairly repeatable. If I fire it again instantly, the fault hasn't
cleared.
A very quick check at low power during fault conditions
demonstrates it is still able to transmit on the selected frequency.
I am suspecting a capacitor issue in the audio circuitry or
earlier in the signal path.
I just wondered if anyone has experienced anything like the same
issue?
73s Ted M7ECH
--
bark less - wag more

Re: QCX 30 and case for sale

Michael Witham

Sold. Thanks!

QCX 30 and case for sale

Michael Witham

As much as I regret, I do not have time for the build let alone operations at present due to professional duties. When I retire, this will change!
I offer an unboxed kit and QRP-LABS case for \$65.00.
I am available at mdwitham@....
Paypal accepted after contact: mdwitham
I will continue to follow and learn!!
Kd4kld

Re: Help Needed QCX Kit parts R17 and R24 installed in reverse

Hello everyone and thank you for your replies.
Hi Juan, Ken, thank you for this info.
Joe, re flowing the solder and wick did actually work.
In inspection of the the holes and track every thing looks OK.
My concern now are the pots OK internally.
With the DVM what should I measure to confirm that I have not damaged them internally.
Before I put them back into the board or should I replace with new ones.
Regards

Re: Help with strange audio fault

Bill Cromwell

Ted,

Do not intentionally short the battery terminals out. If you do be sure to wear adequate eye protection. Have a new fuse on hand and the present fuse between your crowbar and those battery terminals. Batteries can and do explode when the terminals are shorted out.

73,

Bill KU8H

On 1/14/19 8:37 PM, James Daldry W4JED wrote:
Hi, Ted
On the top side of the board, check the resistance from pin 5 of IC10 to ground. It should be around 10K. Now short the battery terminals out. It should now be about 5K. If it fails these 2 tests you have a connection problem at pin 5.
If you connect your voltmeter to pin 5 (top side, not bottom) and then connect the battery it will probably start at 5-ish volts and gradually drift upward. That's your 5 seconds of audio. One end of R39 should be zero ohms to battery negative and the other end zero ohms to pin 5 of IC10, measured on the top of the board. I keep stressing "top of the board" because there may be a bad solder joint or an open piece of foil at pin 5. The break may be invisible. It's possible that R39 is open but so unlikely that I would exhaust all other possibilities before changing it out. Oh, the other foil that could have a problem is from R39 to ground.
Jim Daldry W4JED
On 1/14/19 2:01 PM, qrp@runway23.com wrote:
Just a quick update.

I am still struggling to track this fault down but I do now have some data from my latest investigation.
Do note that this QSX40 set aligned perfectly and was working fine for 2 weeks.

The fault is no receiver output. However if I turn it off for an hour, it fires up again for about 5 seconds and then fades out. This is repeatable. If I fire it again instantly, the fault hasn't cleared and stays silent.

I have been around every solder joint with the iron, not very scientific but sometimes it is a quick fix.

So I though I would start at the beginning with a factory reset and realignment.
8.7 Peak BPF worked fine and produced its normal deafening output.
However 8.8 I-Q Bal, 8.9 Phase Lo and 8.10 Phase Hi are all at 0
Given this alignment needs audio from the output stage, this I think is a fairly good pointer.

IC9 Voltages
1) 4.78
2) 4.78
3) 4.45
4) 0
5) 2.44
6) 2.45
7) 2.45
8) 12

And now IC10, these voltages are clearly wrong
1) 11.06
2) 11.06
3) 11.09
4) 0
5) 5.88
6) 5.36
7)11.10
8) 12

I have been over and over the PCB looking for shorts and dry joints around IC10 and IC09 to no avail (that doesn't mean they don't exist)
The weird part is that after leaving the set off, after time it will always fire up for a few seconds before fading away.

I am going to get my supper and then have another bash but any pointers at all would be most gratefully received.

73 Ted M7ECH

On Thu, Jan 10, 2019 at 02:13 PM, <qrp@runway23.com> wrote:

Just before I remove the QCX40 from its enclosure to fault find, I
thought I would share it in case anyone else had ever experienced
a similar issue.

My QCX40 rev4 has been performing beautifully for about a month
now since it was built.
It is installed in a bespoke enclosure with a alternative volume
control with a power switch.

The fault first manifested itself about 2 weeks ago, I had left
the set on all day but when I went to listen out later in the
evening, there was no audible output.
I had some work to complete so I turned it off for a few hours but
when I switched it back on, all perfect again!
It remained fine for about 5 minutes and then it just went quiet
again, not instantly but as though a volume control was being
turned down.
It was now late so I left it overnight with a view to fault find
it in the morning.
Of course in the morning all fine again!

It has been fine until a few days ago when the fault returned.
If I turn it off for an hour, it fires up again fine but then the
gremlin in there turns the audio down after about 20 secs. This is
fairly repeatable. If I fire it again instantly, the fault hasn't
cleared.

A very quick check at low power during fault conditions
demonstrates it is still able to transmit on the selected frequency.
I am suspecting a capacitor issue in the audio circuitry or
earlier in the signal path.

I just wondered if anyone has experienced anything like the same
issue?

73s Ted M7ECH
--
bark less - wag more

Re: Help with strange audio fault

James Daldry W4JED

Hi, Ted

On the top side of the board, check the resistance from pin 5 of IC10 to ground. It should be around 10K. Now short the battery terminals out. It should now be about 5K. If it fails these 2 tests you have a connection problem at pin 5.

If you connect your voltmeter to pin 5 (top side, not bottom) and then connect the battery it will probably start at 5-ish volts and gradually drift upward. That's your 5 seconds of audio. One end of R39 should be zero ohms to battery negative and the other end zero ohms to pin 5 of IC10, measured on the top of the board. I keep stressing "top of the board" because there may be a bad solder joint or an open piece of foil at pin 5. The break may be invisible. It's possible that R39 is open but so unlikely that I would exhaust all other possibilities before changing it out. Oh, the other foil that could have a problem is from R39 to ground.

Jim Daldry W4JED

On 1/14/19 2:01 PM, qrp@... wrote:
Just a quick update.

I am still struggling to track this fault down but I do now have some data from my latest investigation.
Do note that this QSX40 set aligned perfectly and was working fine for 2 weeks.

The fault is no receiver output. However if I turn it off for an hour, it fires up again for about 5 seconds and then fades out. This is repeatable. If I fire it again instantly, the fault hasn't cleared and stays silent.

I have been around every solder joint with the iron, not very scientific but sometimes it is a quick fix.

So I though I would start at the beginning with a factory reset and realignment.
8.7 Peak BPF worked fine and produced its normal deafening output.
However 8.8 I-Q Bal, 8.9 Phase Lo and 8.10 Phase Hi are all at 0
Given this alignment needs audio from the output stage, this I think is a fairly good pointer.

IC9 Voltages
1) 4.78
2) 4.78
3) 4.45
4) 0
5) 2.44
6) 2.45
7) 2.45
8) 12

And now IC10, these voltages are clearly wrong
1) 11.06
2) 11.06
3) 11.09
4) 0
5) 5.88
6) 5.36
7)11.10
8) 12

I have been over and over the PCB looking for shorts and dry joints around IC10 and IC09 to no avail (that doesn't mean they don't exist)
The weird part is that after leaving the set off, after time it will always fire up for a few seconds before fading away.

I am going to get my supper and then have another bash but any pointers at all would be most gratefully received.

73 Ted M7ECH

On Thu, Jan 10, 2019 at 02:13 PM, <qrp@...> wrote:
Just before I remove the QCX40 from its enclosure to fault find, I thought I would share it in case anyone else had ever experienced a similar issue.

My QCX40 rev4 has been performing beautifully for about a month now since it was built.
It is installed in a bespoke enclosure with a alternative volume control with a power switch.

The fault first manifested itself about 2 weeks ago, I had left the set on all day but when I went to listen out later in the evening, there was no audible output.
I had some work to complete so I turned it off for a few hours but when I switched it back on, all perfect again!
It remained fine for about 5 minutes and then it just went quiet again, not instantly but as though a volume control was being turned down.
It was now late so I left it overnight with a view to fault find it in the morning.
Of course in the morning all fine again!

It has been fine until a few days ago when the fault returned.
If I turn it off for an hour, it fires up again fine but then the gremlin in there turns the audio down after about 20 secs. This is fairly repeatable. If I fire it again instantly, the fault hasn't cleared.

A very quick check at low power during fault conditions demonstrates it is still able to transmit on the selected frequency.
I am suspecting a capacitor issue in the audio circuitry or earlier in the signal path.

I just wondered if anyone has experienced anything like the same issue?

73s Ted M7ECH

Re: Another QCX on the air

Ken Bell

On Sun, Jan 13, 2019 at 10:52 AM, Chopper wrote:
Chopper, I've ordered the QRP Guys antenna and tuner and this is what I intend to run with it.  This setup was for testing the new board and I used what I had on hand. I need buy a bnc - bnc cable for such things.

Re: Help with strange audio fault

Ted 2E0THH

OK
That's me done for tonight, no closer as yet.
One curious thing, I am running from a battery and while I was looking through settings I turned on the battery level icon, however it is empty.
Probably unrelated and some other setting is incorrect.
73s from Cambridge UK
Ted M7ECH

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