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Finished to build but LCD noise.

 

I've finished the Bitx40 experimental project today. I added the AF-AGC and LM386 POP limitter with raduino v1.20.1 (Thanks Allard). And I also added the DuinoVOX for Digital Mode operation. It's a great radio but the problem is only the "LCD noise" when increasing the AF volume. hi... Can I reduce this noise? Or I have to use the analog VFO? Any suggestions welcome.

ja9mat Hidehiko.

IMG_0226.JPG
IMG_0229.JPG

 

the power supply going to raduino has to be filtered at -close to raduino? by say 100uF and? 0.1? disc cap or MLC cap.
?

On Sat, Jul 29, 2017 at 1:52 PM, <qrper72@...> wrote:

I've finished the Bitx40 experimental project today. I added the AF-AGC and LM386 POP limitter with raduino v1.20.1 (Thanks Allard). And I also added the DuinoVOX for Digital Mode operation. It's a great radio but the problem is only the "LCD noise" when increasing the AF volume. hi... Can I reduce this noise? Or I have to use the analog VFO? Any suggestions welcome.

ja9mat Hidehiko.




--
Regards
Sarma
?
Jack Purdum
 

I had the same noise problem with my TFT display. Because of all the add-on boards that Dennis is working on, I needed additional takeoff points for +/-12V (mainly for BITX40, PA, and Dennis' boards) and +/- 8V (the TFT and my DDS). My original design for the PS introduced a ground loop into the circuit and updating the display created an ugly "whoosing" sound. (Hey! What do I know? I'm a software guy.) Under the guidance of Al Peter, AC8GY, I redid the PS (see picture) to eliminate the ground loop. The power comes into the pins on the left, and the yellow pins at the top of the board are +12V feeds (black is GND), the middle yellow pins are +8V for my PCB (less stress on the Mega), and the bottom single set is for the PA. The lone yellow pin near the top right feeds into pin A14 on the Mega to monitor the supply voltage (which might be a battery) on the display. Now there is no interference when tuning.

Jack, W8TEE?


From: Mvs Sarma <mvssarma@...>
To: BITX20@groups.io
Sent: Saturday, July 29, 2017 5:22 AM
Subject: Re: [BITX20] Finished to build but LCD noise.

the power supply going to raduino has to be filtered at -close to raduino? by say 100uF and? 0.1? disc cap or MLC cap.
?

On Sat, Jul 29, 2017 at 1:52 PM, <qrper72@...> wrote:

I've finished the Bitx40 experimental project today. I added the AF-AGC and LM386 POP limitter with raduino v1.20.1 (Thanks Allard). And I also added the DuinoVOX for Digital Mode operation. It's a great radio but the problem is only the "LCD noise" when increasing the AF volume. hi... Can I reduce this noise? Or I have to use the analog VFO? Any suggestions welcome.

ja9mat Hidehiko.




--
Regards
Sarma
?



Virus-free.

PowerSupplyModule.jpg

 

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Please Jack,
send us the schematic of the modified PSU.
?
73 Carlos
CX8ABF
?

Sent: Saturday, July 29, 2017 11:44 AM
Subject: Re: [BITX20] Finished to build but LCD noise.
?
I had the same noise problem with my TFT display. Because of all the add-on boards that Dennis is working on, I needed additional takeoff points for +/-12V (mainly for BITX40, PA, and Dennis' boards) and +/- 8V (the TFT and my DDS). My original design for the PS introduced a ground loop into the circuit and updating the display created an ugly "whoosing" sound. (Hey! What do I know? I'm a software guy.) Under the guidance of Al Peter, AC8GY, I redid the PS (see picture) to eliminate the ground loop. The power comes into the pins on the left, and the yellow pins at the top of the board are +12V feeds (black is GND), the middle yellow pins are +8V for my PCB (less stress on the Mega), and the bottom single set is for the PA. The lone yellow pin near the top right feeds into pin A14 on the Mega to monitor the supply voltage (which might be a battery) on the display. Now there is no interference when tuning.

Jack, W8TEE


From: Mvs Sarma <mvssarma@...>
To: BITX20@groups.io
Sent: Saturday, July 29, 2017 5:22 AM
Subject: Re: [BITX20] Finished to build but LCD noise.
?
the power supply going to raduino has to be filtered at -close to raduino? by say 100uF and? 0.1? disc cap or MLC cap.
?
?
On Sat, Jul 29, 2017 at 1:52 PM, <qrper72@...> wrote:

I've finished the Bitx40 experimental project today. I added the AF-AGC and LM386 POP limitter with raduino v1.20.1 (Thanks Allard). And I also added the DuinoVOX for Digital Mode operation. It's a great radio but the problem is only the "LCD noise" when increasing the AF volume. hi... Can I reduce this noise? Or I have to use the analog VFO? Any suggestions welcome.

ja9mat Hidehiko.




--
Regards
Sarma
?



Virus-free.

Jack Purdum
 

I'll try to get that done this weekend and then post it.

Jack, W8TEE


From: CX8ABF Carlos Molina <cx8abf@...>
To: BITX20@groups.io
Sent: Saturday, July 29, 2017 10:55 AM
Subject: Re: [BITX20] Finished to build but LCD noise.

Please Jack,
send us the schematic of the modified PSU.
?
73 Carlos
CX8ABF
?
Sent: Saturday, July 29, 2017 11:44 AM
Subject: Re: [BITX20] Finished to build but LCD noise.
?
I had the same noise problem with my TFT display. Because of all the add-on boards that Dennis is working on, I needed additional takeoff points for +/-12V (mainly for BITX40, PA, and Dennis' boards) and +/- 8V (the TFT and my DDS). My original design for the PS introduced a ground loop into the circuit and updating the display created an ugly "whoosing" sound. (Hey! What do I know? I'm a software guy.) Under the guidance of Al Peter, AC8GY, I redid the PS (see picture) to eliminate the ground loop. The power comes into the pins on the left, and the yellow pins at the top of the board are +12V feeds (black is GND), the middle yellow pins are +8V for my PCB (less stress on the Mega), and the bottom single set is for the PA. The lone yellow pin near the top right feeds into pin A14 on the Mega to monitor the supply voltage (which might be a battery) on the display. Now there is no interference when tuning.

Jack, W8TEE


From: Mvs Sarma <mvssarma@...>
To: BITX20@groups.io
Sent: Saturday, July 29, 2017 5:22 AM
Subject: Re: [BITX20] Finished to build but LCD noise.
?
the power supply going to raduino has to be filtered at -close to raduino? by say 100uF and? 0.1? disc cap or MLC cap.
?
?
On Sat, Jul 29, 2017 at 1:52 PM, <qrper72@...> wrote:

I've finished the Bitx40 experimental project today. I added the AF-AGC and LM386 POP limitter with raduino v1.20.1 (Thanks Allard). And I also added the DuinoVOX for Digital Mode operation. It's a great radio but the problem is only the "LCD noise" when increasing the AF volume. hi... Can I reduce this noise? Or I have to use the analog VFO? Any suggestions welcome.

ja9mat Hidehiko.




--
Regards
Sarma
?



Virus-free.


 

开云体育

Thanks Jack
73 Carlos
?

Sent: Saturday, July 29, 2017 12:05 PM
Subject: Re: [BITX20] Finished to build but LCD noise.
?
I'll try to get that done this weekend and then post it.

Jack, W8TEE


From: CX8ABF Carlos Molina <cx8abf@...>
To: BITX20@groups.io
Sent: Saturday, July 29, 2017 10:55 AM
Subject: Re: [BITX20] Finished to build but LCD noise.
?
Please Jack,
send us the schematic of the modified PSU.
?
73 Carlos
CX8ABF
?
Sent: Saturday, July 29, 2017 11:44 AM
Subject: Re: [BITX20] Finished to build but LCD noise.
?
I had the same noise problem with my TFT display. Because of all the add-on boards that Dennis is working on, I needed additional takeoff points for +/-12V (mainly for BITX40, PA, and Dennis' boards) and +/- 8V (the TFT and my DDS). My original design for the PS introduced a ground loop into the circuit and updating the display created an ugly "whoosing" sound. (Hey! What do I know? I'm a software guy.) Under the guidance of Al Peter, AC8GY, I redid the PS (see picture) to eliminate the ground loop. The power comes into the pins on the left, and the yellow pins at the top of the board are +12V feeds (black is GND), the middle yellow pins are +8V for my PCB (less stress on the Mega), and the bottom single set is for the PA. The lone yellow pin near the top right feeds into pin A14 on the Mega to monitor the supply voltage (which might be a battery) on the display. Now there is no interference when tuning.

Jack, W8TEE


From: Mvs Sarma <mvssarma@...>
To: BITX20@groups.io
Sent: Saturday, July 29, 2017 5:22 AM
Subject: Re: [BITX20] Finished to build but LCD noise.
?
the power supply going to raduino has to be filtered at -close to raduino? by say 100uF and? 0.1? disc cap or MLC cap.
?
?
On Sat, Jul 29, 2017 at 1:52 PM, <qrper72@...> wrote:

I've finished the Bitx40 experimental project today. I added the AF-AGC and LM386 POP limitter with raduino v1.20.1 (Thanks Allard). And I also added the DuinoVOX for Digital Mode operation. It's a great radio but the problem is only the "LCD noise" when increasing the AF volume. hi... Can I reduce this noise? Or I have to use the analog VFO? Any suggestions welcome.

ja9mat Hidehiko.




--
Regards
Sarma
?



Virus-free.


Jack Purdum
 

I'm just getting started with Diptrace, so this is the best I can do right now.


Inline image
All of the electrolytic capacitors are 330uF 16V and all the rest are 0.1uF disk ceramics. I separated out J1's 12V in case I want to up the voltage and throw a 7812 into the other leg. I probably should have used higher voltage caps, but it's what I have on hand and, so far, seems to work fine. Each set of ground pins associated with each connector is tied to the ground leg of the final bypass capacitor. That is, the ground pins for J2 tie to the ground leg of C4, for J3 it's C13, and for J1 it's C12. I had connectors on the schematic for the ground pins, but I thought it cluttered it up. The single ground point is important.

I'm sure someone with real EE skills can do a better job with the schematic and explanation of avoiding a ground loop. I've attached a JPG of the schematic, too.

Jack, W8TEE


From: CX8ABF Carlos Molina <cx8abf@...>
To: BITX20@groups.io
Sent: Saturday, July 29, 2017 11:57 AM
Subject: Re: [BITX20] Finished to build but LCD noise.

Thanks Jack
73 Carlos
?
Sent: Saturday, July 29, 2017 12:05 PM
Subject: Re: [BITX20] Finished to build but LCD noise.
?
I'll try to get that done this weekend and then post it.

Jack, W8TEE


From: CX8ABF Carlos Molina <cx8abf@...>
To: BITX20@groups.io
Sent: Saturday, July 29, 2017 10:55 AM
Subject: Re: [BITX20] Finished to build but LCD noise.
?
Please Jack,
send us the schematic of the modified PSU.
?
73 Carlos
CX8ABF
?


Virus-free.




PowerSupplySchematic.jpg

 

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About “ground loops” please read...
?
?
?

Sent: Saturday, July 29, 2017 11:08 PM
Subject: Re: [BITX20] Finished to build but LCD noise.
?
I'm just getting started with Diptrace, so this is the best I can do right now.


Inline image
All of the electrolytic capacitors are 330uF 16V and all the rest are 0.1uF disk ceramics. I separated out J1's 12V in case I want to up the voltage and throw a 7812 into the other leg. I probably should have used higher voltage caps, but it's what I have on hand and, so far, seems to work fine. Each set of ground pins associated with each connector is tied to the ground leg of the final bypass capacitor. That is, the ground pins for J2 tie to the ground leg of C4, for J3 it's C13, and for J1 it's C12. I had connectors on the schematic for the ground pins, but I thought it cluttered it up. The single ground point is important.

I'm sure someone with real EE skills can do a better job with the schematic and explanation of avoiding a ground loop. I've attached a JPG of the schematic, too.

Jack, W8TEE


From: CX8ABF Carlos Molina <cx8abf@...>
To: BITX20@groups.io
Sent: Saturday, July 29, 2017 11:57 AM
Subject: Re: [BITX20] Finished to build but LCD noise.
?
Thanks Jack
73 Carlos
?
Sent: Saturday, July 29, 2017 12:05 PM
Subject: Re: [BITX20] Finished to build but LCD noise.
?
I'll try to get that done this weekend and then post it.

Jack, W8TEE


From: CX8ABF Carlos Molina <cx8abf@...>
To: BITX20@groups.io
Sent: Saturday, July 29, 2017 10:55 AM
Subject: Re: [BITX20] Finished to build but LCD noise.
?
Please Jack,
send us the schematic of the modified PSU.
?
73 Carlos
CX8ABF
?
?

Virus-free.




 

do this....


?

--
Paul Mateer, AA9GG
Elan Engineering Corp.

NAQCC 3123, SKCC 4628

Virus-free.

 

I did this, but less: Vin raw (no cap needed), 10E as yours, 220uF across supply to DDS (direct across pins of 7805 regulator, +Vin is away from pot.). Bits scrapped from a duff PC PSU. Worked a treat for me. I'd posted this earlier, but your diagram draws the 'picture worth a thousand words'. :) 73 all, Dex ZL2DEX
 

TKS to all suggested to me.

Well I added the 2000uFx2+10ohm filter between the main 13.5V and the Raduino's regulator input. I feel it's efficient and the LCD noise has almost gone. After this Mod. I can hear -127dBm from hp8656B signal generator. Before this Mod. the sensiticvity was only -115dBm because of the LCD noise.

ja9mat Hidehiko.
 

Hidehiko-san: ? An active decoupler circuit in the AF amp DC power line might help. ? Just three parts:?
? 73? Bill N2CQR




On Saturday, July 29, 2017 4:22 AM, "qrper72@..." <qrper72@...> wrote:


I've finished the Bitx40 experimental project today. I added the AF-AGC and LM386 POP limitter with raduino v1.20.1 (Thanks Allard). And I also added the DuinoVOX for Digital Mode operation. It's a great radio but the problem is only the "LCD noise" when increasing the AF volume. hi... Can I reduce this noise? Or I have to use the analog VFO? Any suggestions welcome.

ja9mat Hidehiko.
 

Thanks Bill more suggestion, I will try...

ja9mat Hidehiko.
 

?????????????????????????????????????????????????????????????

On Wed, Aug 2, 2017 at 3:21 PM, <qrper72@...> wrote:
Thanks Bill more suggestion, I will try...

ja9mat Hidehiko.




--
Regards
Sarma
?

22nf related.PNG

 

please don't care for my message
?it was to be sent some one else.
?? i request moderator , help remove the message, please.
 

Hello Bill,
I've read all about the active decoupling but sorry I can't understand the values of this circuit. Do I have to calclate these values C and R ? If there is an example circuit it may help me.

ja9mat Hidehiko.
 

Hidehiko:?

Very simple.? Just three parts. ? NPN transistor (like a 2N3904) and a 47k resistor (collector to base) 100 uF cap (base to ground). ? Vcc the collector. Emitter goes to the DC power input of the AF amplifier. ?

You can see my use of this circuit in the schematic in this blog post:
Look in the lower right, near the LM386 AF amplifier.? Click on the schematic to enlarge.? 73? Bill N2CQR?


?


On Thursday, August 3, 2017 4:19 AM, "qrper72@..." <qrper72@...> wrote:


Hello Bill,
I've read all about the active decoupling but sorry I can't understand the values of this circuit. Do I have to calclate these values C and R ? If there is an example circuit it may help me.

ja9mat Hidehiko.


 

For the BITX40, possibly even simpler: just 'tombstone' R113, add that 47k resistor from there to NPN base + C114, NPN Collector to R111,R113,D18 junction, NPN emitter feeds similarly 'tombstoned' R112. Theory: R113 by itself overdrives the NPN, and the extra 47k (would 100k give enough drive? possibly device-dependent.) gives better time-constant with C114. Caveat: not tested personally; mine's quiet enough with the Raduino's supply filtered with 10E and 220uF.
 

Thanks Bill,

Well I added "3-parts"(2N3904+47kohm+100uF) between the D18(1N4148) and the junction of R111(100ohm) and R1113(220ohm). The noise has absolutely gone! Both the power line of AF Pre Amp and LM386 PA are connected to the emitter of 2N3904. Is this right? Your recommended circuit connected to AF Pre Amp only.

ja9mat Hidehiko.
 

Hidehiko:? I am happy that the circuit eliminated the LCD noise. ? Mine was connected only to the AF pre-amp, on the theory that that was where the noise was being picked up most significantly. ? But connecting it to all AF amps seems like a good option too.? Amazing what three parts can do.? 73? Bill N2CQR


On Friday, August 4, 2017 4:46 AM, "qrper72@..." <qrper72@...> wrote:


Thanks Bill,

Well I added "3-parts"(2N3904+47kohm+100uF) between the D18(1N4148) and the junction of R111(100ohm) and R1113(220ohm). The noise has absolutely gone! Both the power line of AF Pre Amp and LM386 PA are connected to the emitter of 2N3904. Is this right? Your recommended circuit connected to AF Pre Amp only.

ja9mat Hidehiko.


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