Part 4 Of A Digital VFO For The G6LBQ Irwell HF Transceiver

For part 1 of the Digital VFO click here.

For part 2 of the Digital VFO click here.

For part 3 of the Digital VFO click here.

Digital VFO & RF Oscillator Module

"For the G6LBQ Irwell HF Transceiver"

Welcome to part 4 of my blog post series detailing the Digital VFO and RF oscillator module for my “Irwell HF Transceiver" project.  

The PCBs have arrived from the fabrication plant so it is now time to get busy with the soldering iron and hopefully call time on this part of the project, or at least for now. Providing there are no issues with the PCBs or hardware, all that remains to be done is software updates to coincide with the future development of the project.

A trio of G6LBQ VFO boards.

Global Component Crisis

Throughout 2020 and now 2021, there has been considerable disruption in the supply chain of electronic components and, in particular, semiconductors, with lead times continually extending and prices rising. At the beginning of March 2021, I ordered a quantity of SI5351 ICs from RS Components and now five months down the line, I have still not received them and the current scheduled delivery date is January 2022, though this could change with further extensions.

The cause of the global component crisis is due to a combination of different events, with the COVID-19 pandemic being the primary reason. Other factors that have contributed to the problem include:

• The China & United States trade war
• Taiwan drought
• A general shortage of raw materials
• A fire at the Renesas semiconductor plant in Tokyo Japan
  

The impact of the global component shortage has affected many manufactures and sectors who are reliant on their supply chains and at a time when the demand for consumer electronics is at an all-time high, it is, without doubt a global calamity.

The problem is likely to continue well into 2022 so for now "the chips are well and truly down"!

I felt compelled to mention the component crisis, as it does affect our hobby. The availability of certain components is now proving to be a problem for myself and delays progress. Last week I went on the RS Components website to order ULN2803A darlington array ICs for the digital VFO I/O board and this is what I was presented with:

 

The availability of the ULN2803A ICs is not much of an issue at the moment, as I won't be needing the I/O Board until I develop the bandpass & low-pass filter modules so for now I will set this aside.

Fortunately, I had exactly three SI5351 ICs in my component stock so I have been able to build the VFO oscillator and Display controller boards.

Here is an image of the finished VFO controller board showing the top side of the PCB without the display connected:

Actual PCB Size is 110mm by 75mm.

And next is a bottom or back view of the VFO controller PCB:

Actual PCB Size is 110mm by 75mm.

Here is an image of the finished VFO Oscillator board showing the top side of the PCB:

Actual PCB Size is 110mm by 75mm.

And next is a bottom or back view of the VFO oscillator PCB:

Actual PCB Size is 110mm by 75mm

The controller and oscillator boards have been designed so they connect together with PCB headers. These are then secured in place using M3 brass pillars and screws, as shown below:

 Here is a different view of the boards connected together:

The four unused mounting holes and header connector that can be seen on the left hand side of the oscillator board are used to mount the I/O board.

Finally the VFO can be seen working but I must apologize for the poor quality of the image, it does not do justice to the display:

I was relieved and pleased that the VFO worked the first time and the 3.2" TFT display is  clear to view and a nice size.

The next module that I will be tackling is the receiver bandpass filters and once I have done this, I will come back to the VFO and hopefully build the additional I/O module pending the availability of parts!

Project files and software will soon be made available via the Groups.io platform by joining my G6LBQ community group, where you can discuss my projects, ask questions and help others.

For part 5 of the Digital VFO, click here.

 

Joining my group is free. Just click on the button below.

 

 

 Until next time...

 

  

 

73's From Andy G6LBQ

Its all about the Radio Ga Ga...