Hi All,
My issue has been resolved. The mistake was mine. The Mini circuit VCO runs on 3.3V and 5V. The Oscillator and buffer portion are on 5V, however the ADF I/F is running at 3.3v.
Although I had the data sheet, I completely overlooked the fact that the ADF is 3.3V and the Picaxe ran from 5 V. As a result the ADF failed due to excessive voltages on the SPI port(s).
The ADF4106 is a fantastic PLL, so easy to use and implement when combined with a Picaxe for simple singular operation and loading.
Thank you for the support.
Regards
Gerald
VK3GJM