?

Hi Paul

The NE5534’s provide the gain for the various IF modes.

>>You asked why U1A and U1B are needed and are two buffers better than one

U1A and U1B split the audio path for the USB/LSB and CW modes of operation to the main TDA2003 audio amplifier and the line output driver so one buffer for each signal path.

U1A is proceeded by a further buffer stage U2B so yes there are two buffers and to answer your question NO two buffers are not better than one but, in this case, they serve a purpose.

As already mentioned, U1A and U1B split the ssb/cw audio path but that is not there only job! ?For digital modes I want the audio to go to U2A the line output driver but not the TDA2003 audio amplifier.? For digital modes silence is golden ? so by muting U1B we don’t have to listen to the digi modes racket and it just gets passed onto the line driver stage via U1A & U2B.

So why proceed U1A with U2B?? The answer is simple, muting. I can mute the line stage independently of the USB/CW audio path.

>> You asked about the 4066 switch and in particular if it was noiseless during switching

The answer is yes.

>> You asked if I could provide indicative bandpass values for the NE5534 pre-amp?

I modelled the pre-amps in Spice simulation and when I get some spare time I will re-visit the files and post an update to the blog post with further information.

>>You asked, can you explain the meaning of virtual ground?

In general Op-Amps are designed to run from dual supply rails but in my circuit they operate from a single supply rail, the virtual ground serves to bias the op-amps halfway between ground and the single supply rail.

I hope this explains the operation of my audio module a little clearer.

Regards

Andy (G6LBQ)

Hi Paul?

If you go to Andys blog page via google (G6LBQ BLOG) it may help you if not Andy will I am sure will help you with some answers if you send him a message

hope this helps regards? Frank G6YAQ

Andy and others

The Irwell modules are interesting, thanks for sharing these.? I've been studying the Audio module.

It appears that all of the preamp gain is via U1 NE5534, which includes filtering. I am not smart enough to recognise what the textbook configuration is for this stage.? Can someone enlighten and also provide indicative bandpass for these values?

I am also wondering why U1A and U1B (NE5532) are needed. U1A is configured as a voltage follower to give high input impedance and low output impedeance, but why follow it with a second op amp?? Are two better than one?? Was it a small gain for no extra parts, given one was available in the dual package?

Finally, can you explain the meaning of virtual ground? I'm guessing this is a grounding arrangement to avoid earth loops that could lead to hum.? I am not sure how to build it.?

73 Paul VK3HN.?

The following files have been uploaded to the Files area of the [email protected] group.

• /G6LBQ Irwell Transceiver/Irwell Transceiver Audio Sub-System/PCB Files For Irwell Transceiver AF Sub-System/G6LBQ Irwell AF Schematic.pdf

By: g6lbq <ah.electronics@...>

Description:
Schematic diagram for the Irwell transceiver audio subsystem.

The following files have been uploaded to the Files area of the [email protected] group.

• /G6LBQ Irwell Transceiver/Irwell Transceiver Audio Sub-System/PCB Files For Irwell Transceiver AF Sub-System/Irwell_AF_Top.pdf

By: g6lbq <ah.electronics@...>

Description:
Document containing Irwell Transceiver AF subsystem PCB top layer. Its a high res PDF printable document.

---

The following files have been uploaded to the Files area of the [email protected] group.

• /G6LBQ Irwell Transceiver/Irwell Transceiver Audio Sub-System/PCB Files For Irwell Transceiver AF Sub-System/Irwell_AF_Top_Mirrored.pdf

By: g6lbq <ah.electronics@...>

Description:
Document containing Irwell Transceiver AF subsystem PCB top layer mirrored. Its a high res PDF printable document.

---

The following files have been uploaded to the Files area of the [email protected] group.

• /G6LBQ Irwell Transceiver/Irwell Transceiver Audio Sub-System/PCB Files For Irwell Transceiver AF Sub-System/Irwell_AF_Bottom.pdf

By: g6lbq <ah.electronics@...>

Description:
Document containing Irwell Transceiver AF subsystem PCB bottom layer. Its a high res PDF printable document.

---

The following files have been uploaded to the Files area of the [email protected] group.

• /G6LBQ Irwell Transceiver/Irwell Transceiver Audio Sub-System/PCB Files For Irwell Transceiver AF Sub-System/Irwell_AF_Bottom_Mirrored.pdf

By: g6lbq <ah.electronics@...>

Description:
Document containing Irwell Transceiver AF subsystem PCB bottom layer mirrored. Its a high res PDF printable document.

---

The following files have been uploaded to the Files area of the [email protected] group.

• /G6LBQ Irwell Transceiver/Irwell Transceiver Audio Sub-System/PCB Files For Irwell Transceiver AF Sub-System/G6LBQ Populated PCB.pdf

By: g6lbq <ah.electronics@...>

Description:
Picture of a completed Irwell audio subsystem PCB.

Hi all
Just letting you know more notes / updates /etc, on the Irwell and other interesting topics can be found on Andys Blog site pages
Enter on google search to view? ?G6LBQ BLOG? and all will be revealed!!
Keep busy and stay safe 73 Frank G6YAQ

The following files have been uploaded to the Files area of the [email protected] group.

• /G6LBQ Irwell Transceiver/Irwell Transceiver Audio Sub-System/PCB Files For Irwell Transceiver AF Sub-System/PCB Dimensions with CAD view.pdf

By: g6lbq <ah.electronics@...>

Description:
Document containing PCB dimensions & CAD view image of Irwell AF Sub-System PCB.

---

The following files have been uploaded to the Files area of the [email protected] group.

• /G6LBQ Irwell Transceiver/Irwell Transceiver Audio Sub-System/PCB Files For Irwell Transceiver AF Sub-System/Irwell_AF_PCB.pdf

By: g6lbq <ah.electronics@...>

Description:
Document containing printable PCB layout for the Irwell AF Sub-System PCB.

---

The following files have been uploaded to the Files area of the [email protected] group.

• /G6LBQ Irwell Transceiver/Irwell Transceiver Audio Sub-System/PCB Files For Irwell Transceiver AF Sub-System/Irwell_AF_PCB_Mirrored.pdf

By: g6lbq <ah.electronics@...>

Description:
Document containing mirrored printable PCB layout for the Irwell AF Sub-System PCB.

The following files have been uploaded to the Files area of the [email protected] group.

• /G6LBQ Irwell Transceiver/Irwell Transceiver Audio Sub-System/G6LBQ Populated PCB.pdf

By: g6lbq <ah.electronics@...>

Description:
Fully populated PCB - PDF document with photograph of finished module.

The following files have been uploaded to the Files area of the [email protected] group.

• /G6LBQ Irwell Transceiver/Irwell Transceiver Audio Sub-System/G6LBQ Irwell AF.pdf

By: g6lbq <ah.electronics@...>

Description:
Schematic diagram for the Irwell Transceiver audio sub-system. Revision 1.0

The following files have been uploaded to the Files area of the [email protected] group.

• /G6LBQ Irwell Transceiver/Irwell Audio DSP Noise Reduction/Arduino Controller Software/BHI_DSP_Control.ino

By: g6lbq <ah.electronics@...>

Description:
Revision 1 of my BHI noise reduction DSP controller software

The following files have been uploaded to the Files area of the [email protected] group.

• /G6LBQ Irwell Transceiver/Irwell Audio DSP Noise Reduction/G6LBQ Irwell Audio DSP Controller Rev1.pdf

By: g6lbq <ah.electronics@...>

Description:
Schematic diagram for the BHI DSP noise reduction controller by G6LBQ as used in the Irwell HF Transceiver.

Hello? to all,
Just letting you know the Irwell high spec tcvr is nearing completion after many ups and downs
and an update by Andy is due on developments in the very near future.
Another project also in the pipeline is the Allstar link node transceiver and has inf on what and what not to be aware of if you are building it, which can be followed on Andy,s
blog pages,(google search G6LBQ BLOG) for some very interesting reading on all of the items.
So poss irons at the ready soon
STAY SAFE?
Best 73 to all? G6YAQ Frank

Ian did the board arrive?

Chris

Hi Adrian

Thank you for your reply and your findings on your build and will be taken onboard on our way forward.

We only produced the board for our group and used/supplied the info for that board.? We had no intention to supply others with them but we had a
spare and it was good to help someone else out with it.

Ill let you know how we get on with them and looks like we could have a bit of teetering further on.

Thank you again Chris

开云体育

Hi Chris

The genuine G6LBQ V3 PCB is near identical to the PCB image you have sent out. However your image says V2...this could lead to confusion. The G6LBQ files for the PCB are in the Irwell folder on the IO Groups website.

The G6LBQ V2 PCB can be identified because it does not have the BD139? transistor. I have built the original G6LBQ V2 and I have found that it has a tendancy to oscillate uncontollably. Despite many attempts to stop this, I eventually gave up with the G6LBQ V2 board and built my own amplifier stage which develops around 25 watts. Good RF design practice when designing the PCB is key here.?

Hence my question about how you got on, I was keen to know if you had cured the oscillation problem (seems to be linked to BIAS).

As the G6LBQ is a simple (I mean that as a compliment) transceiver design, good design practice is key to getting it working properly. I discovered issues around power supply filtering being key to noise reduction in RX performance and TX cleanliness, due to the DDS VFO being susceptable to noise. Initally running & testing? on batteries is a good idea.? I have changed the mixer section and improved power supply filtering in my G6LBQ to improve the situation.

I also added a section to improve carrier balance & injection due to the amount of gain in the TX audio stage.

HTH

Adrian M1LCR

This is what we ended up with....

Hi Adrian

We done a group build of them, made our own gerbers and sent them away for production as we couldnt find a source of the PCBs.
I have not built it as yet as we are still waiting on a couple in the group to catch up with 1 or 2 of the more experienced guys with soldering etc. Im sure we wont be long till we all get to the Amp PCB and we will let you know how we all get on.
We all are online in a group on Discord so we can sort out any issues with sources for components to testing and the current Covid rules and we are spread throughout the central belt in Scotland.
I have other projects on the go aswell but its great to help some of the guys out from time to time on their projects and they throw some ideas to me for my new and coming projects. They dont know yet but they will be building them theirselves some time soon ;)

Regards Chris

Hi Ian

I will post it first and we can see what the postage will be, no hurry for the payment. If its a couple of quid im sure you could buy me a cup of tea at the next rally we meet at :) LOL

Ill pop it in the post tomorrow as i was really busy at work today.

Regards Chris