Part 2 Of A Digital VFO For The G6LBQ Irwell HF Transceiver

For part 1 of the Digital VFO click here.

Digital VFO & RF Oscillator Module

"For The G6LBQ Irwell HF Transceiver"

Welcome to part 2 of my blog post series in which I present further details of my Digital VFO and RF oscillator module for the “Irwell HF Transceiver" project. This is a significant building block and is solely responsible for frequency generation and the control of other modules in the project.

Since I posted part 1 on the blog, I have made good progress with the software changes that I outlined. I have added additional commands to JA2GQP’s source code for the I2C Multiplexer and I am now at the stage where I can communicate with two SI5351 devices to produce two chip independent clock signals. In order to achieve this, I have had to make changes to both the main code as well as the SI5351 library file.

For now, I only need to generate two clock signals for my transceiver, one for the VFO and the other for the BFO. This will permit the radio to run as a single conversion superhet in its current state. Once further modules are developed, the receiver will be upgraded to a dual conversion superhet, this will require a third clock signal  for the requisite conversion oscillator.

The additional software code required to support a third SI5351 is going to be a bit more difficult for me to implement. I hope to replicate JA2GQP’s BFO oscillator code for this as it includes a routine for calibrating the BFO frequency and saving it to memory. If I can do this, it should also pave the way for implementing an IF shift control.

Part 1 Of A Digital VFO For The G6LBQ Irwell HF Transceiver

 Digital VFO & RF Oscillator Module

"For the G6LBQ Irwell HF Transceiver"

In this blog post, I present my digital VFO and RF Oscillator module for the Irwell HF Transceiver project, which is based on the Silicon Labs CMOS SI5351 Clock Generator.

Before we begin, I would like to pay homage to an era in my life which has flourished and brought great happiness, prosperity and achievement. 

I make the aforementioned statement with a sense of humbleness and I also feel privileged to have experienced great wealth in the recent flourishing times. 

If all this has got you thinking, I have won the national lottery or been a beneficiary to a nice windfall you are excused and forgiven :)  The truth is I have only ever been good at making other people wealthy and said people choose to forget what the catalyst was for their wealth status. Those people know who they are, shame on you!

I digress a little as I sailed off course for a moment there but suffice to say I am very happy with my modest lifestyle.