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QCX Mini 40m version -Band Pass Filter Alignment Problem

Colin Christie
 

Hi All,

My issue is that I can not align the BPF .

I have checked the following for the 40m version.

I have used the correct red toroid.

Checked the number of turns 38; continuity checked Ok
Checked the number of turns5;? continuity checked? ?Ok
Checked the number of turns5;? continuity checked Ok
Checked the number of turns5;? continuity checked Ok
I have double checked the wiring is in the correct location on the PCB.


C1?checked soldered ok.

Going into 8.0 Alignment I get the loud audio noise in the speakers?.

After going into 8.7 Peak BPF? I get a bar graph moving backwards and forwards rapidly which seems to relate to the audio and? 00 displays.

Now, moving the C1 cap with a screwdriver?there is little to no change in the bar graph?and the number briefly goes to 1 but back to 00.

I am really open to any advice please



73 Colin VK2JCC
 

Hi Colin. If you are hearing the 700 Hz tone in the speaker when in menu 8.7 Peak BPF (not 8.0 Alignment) and if it isn't a strong enough signal to give a reading above 00, then I suspect you have an issue with the enamel removal on L1, L2 or L3. Please do a DC continuity?check (with radio OFF) between the center pin of the BNC connector and the C29 end of L3. If there is no continuity through there, you have a bad connection?in one or more of the lowpass filter toroids and the test signal has to come through there to get to the receiver. So I suspect some amount of test signal is making it through but not enough.Please check that part and report back what you find. Good luck. 73...

Ron

On Tue, Jun 7, 2022 at 9:37 PM Colin Christie <colincolin30@...> wrote:
Hi All,

My issue is that I can not align the BPF .

I have checked the following for the 40m version.

I have used the correct red toroid.

Checked the number of turns 38; continuity checked Ok
Checked the number of turns5;? continuity checked? ?Ok
Checked the number of turns5;? continuity checked Ok
Checked the number of turns5;? continuity checked Ok
I have double checked the wiring is in the correct location on the PCB.


C1?checked soldered ok.

Going into 8.0 Alignment I get the loud audio noise in the speakers?.

After going into 8.7 Peak BPF? I get a bar graph moving backwards and forwards rapidly which seems to relate to the audio and? 00 displays.

Now, moving the C1 cap with a screwdriver?there is little to no change in the bar graph?and the number briefly goes to 1 but back to 00.

I am really open to any advice please



73 Colin VK2JCC
 

By far the most common fault is soldering especially the enameled wire.
The next most common is +1 turn, counting error on the winding.

Allison
-------------------------------
Please reply on list so we can share.
No private email, it goes to a bit bucket due to address harvesting
Colin Christie
 

Hi Ron et al,

?I have?? continuity? between the center pin of the BNC connector and the C29 end of L3.
I did just a double? check reflowed each joint on all the toroids and BNC centre. resistance is 2 ohms across the lot.
cheers Colin VK2JCC


On Thu, 9 Jun 2022 at 02:47, ajparent1/KB1GMX <kb1gmx@...> wrote:
By far the most common fault is soldering especially the enameled wire.
The next most common is +1 turn, counting error on the winding.

Allison
-------------------------------
Please reply on list so we can share.
No private email, it goes to a bit bucket due to address harvesting

 

¿ªÔÆÌåÓý

Look at the circuit diagram, there IS DC continuity to ground from the center pin of the BNC.

On 9 Jun 2022, at 01:58, Colin Christie <colincolin30@...> wrote:

Hi Ron et al,

?I have?? continuity? between the center pin of the BNC connector and the C29 end of L3.
I did just a double? check reflowed each joint on all the toroids and BNC centre. resistance is 2 ohms across the lot.
cheers Colin VK2JCC

On Thu, 9 Jun 2022 at 02:47, ajparent1/KB1GMX <kb1gmx@...> wrote:
By far the most common fault is soldering especially the enameled wire.
The next most common is +1 turn, counting error on the winding.

Allison
-------------------------------
Please reply on list so we can share.
No private email, it goes to a bit bucket due to address harvesting



 

Howard, there is not supposed to be continuity from the BNC center to ground. C29 DC isolates the filter from the rest of the circuit. The only thing to ground are 4 capacitors which better not be showing DC continuity.?

Colin, please check to make sure there is NOT DC continuity from the BNC center pin to ground. If there is you will need to find out why and correct it.?

Ron

On Thu, Jun 9, 2022 at 03:52 howard winwood G4GPF <winwoodh@...> wrote:
Look at the circuit diagram, there IS DC continuity to ground from the center pin of the BNC.

On 9 Jun 2022, at 01:58, Colin Christie <colincolin30@...> wrote:

Hi Ron et al,

?I have?? continuity? between the center pin of the BNC connector and the C29 end of L3.
I did just a double? check reflowed each joint on all the toroids and BNC centre. resistance is 2 ohms across the lot.
cheers Colin VK2JCC

On Thu, 9 Jun 2022 at 02:47, ajparent1/KB1GMX <kb1gmx@...> wrote:
By far the most common fault is soldering especially the enameled wire.
The next most common is +1 turn, counting error on the winding.

Allison
-------------------------------
Please reply on list so we can share.
No private email, it goes to a bit bucket due to address harvesting



 

Dear Howard,
I had a similar problem when building my 30M QCX-Mini.?? My BNC connector mounting pins on the outside ring of the connector? was a little crooked in the solder outlined holes and when I soldered them?? I inadvertently had solder drift over
and short the center pin to the outside of the connector.??? The short occurred from one of the auxiliary holes in the board for making alternate connections for the antenna.connections.? I had the same indications when trying to do the
BPF alignment.? It was hard to see without some magnification.?? so look closely.

take care and have fun.
73 Dave WA5DJJ
SUPER GRABBER https://www.qsl.net/wa5djj/
Colin Christie
 

Hi all,
thanks for the suggestions made to solve my issue relating to not being able to peak my BPFilter.

I have watched the?youtube videos and read as much as i can on the issue. It seems the 40m usually does not have this issue.

I have tried each of the suggestions?and have reflowed just about every soldered joint.?

I have spent my? time looking for shorts between soldered points using an eye loop and strong light.

?I am very happy with the connectivity of both the T1 wiring and the L1,L2,L3 wiring.

I have conductivity between the centre of the BNC and Cap 29.

I can, when I hold my finger on the control board ( where the pins go to the motherboard) hear very, very faintly local broadcast?stations.


I have also lodged a "technical enquiry"?with Hans to get his advice.

Is there something I am missing here, I am not a techie?but self taught in electronics?, so any help will be taken on board.

I am dying to get this little beauty on the air.

73 Colin vk2jcc

On Fri, 10 Jun 2022 at 03:06, David R. Hassall WA5DJJ <dhassall@...> wrote:
Dear Howard,
I had a similar problem when building my 30M QCX-Mini.?? My BNC connector mounting pins on the outside ring of the connector? was a little crooked in the solder outlined holes and when I soldered them?? I inadvertently had solder drift over
and short the center pin to the outside of the connector.??? The short occurred from one of the auxiliary holes in the board for making alternate connections for the antenna.connections.? I had the same indications when trying to do the
BPF alignment.? It was hard to see without some magnification.?? so look closely.

take care and have fun.
73 Dave WA5DJJ
SUPER GRABBER

 

Colin

Assuming you don't have a short between center and outer conductor, I still wonder about having connections at each T1 winding. Reflow may not cure an issue. On one of my qcx I manually scraped insulation above the pad, then added solder and that solved it.?

Several builders completely missed one or more solder joints.?

It is easy not to have some pins soldered.?

It's clearly something there.?

Curt
 

¿ªÔÆÌåÓý

Hi there.

How do you measure the output?
With a wattmeter of with a scope?

IF you have a scope (AND an attenuator!!) please check the shape of the output!.

If it is a solid sine-wave, that already looks promising.
If not, you have a problem¡­



?XS Max (512Gb)

On 14 Jun 2022, at 07:54, Colin Christie <colincolin30@...> wrote:

?
Hi all,
thanks for the suggestions made to solve my issue relating to not being able to peak my BPFilter.

I have watched the?youtube videos and read as much as i can on the issue. It seems the 40m usually does not have this issue.

I have tried each of the suggestions?and have reflowed just about every soldered joint.?

I have spent my? time looking for shorts between soldered points using an eye loop and strong light.

?I am very happy with the connectivity of both the T1 wiring and the L1,L2,L3 wiring.

I have conductivity between the centre of the BNC and Cap 29.

I can, when I hold my finger on the control board ( where the pins go to the motherboard) hear very, very faintly local broadcast?stations.


I have also lodged a "technical enquiry"?with Hans to get his advice.

Is there something I am missing here, I am not a techie?but self taught in electronics?, so any help will be taken on board.

I am dying to get this little beauty on the air.

73 Colin vk2jcc

On Fri, 10 Jun 2022 at 03:06, David R. Hassall WA5DJJ <dhassall@...> wrote:
Dear Howard,
I had a similar problem when building my 30M QCX-Mini.?? My BNC connector mounting pins on the outside ring of the connector? was a little crooked in the solder outlined holes and when I soldered them?? I inadvertently had solder drift over
and short the center pin to the outside of the connector.??? The short occurred from one of the auxiliary holes in the board for making alternate connections for the antenna.connections.? I had the same indications when trying to do the
BPF alignment.? It was hard to see without some magnification.?? so look closely.

take care and have fun.
73 Dave WA5DJJ
SUPER GRABBER

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