Local Oscillator PLL upgrade for
DB6NT MK2 13cm Transverter

It is ten years since I built my MK2 13cm transverter (above). Back then the concept of phase-locking the local oscillator of such things was a relatively major project and to be honest, I wasn’t too worried about frequency accuracy since I had a couple of ways of verifying and compensating for any offset. A few months ago, a friend of mine purchased two of OZ5N’s ‘Auto-PLL’ kits … one for his 13cm transverter and the other for his 9cm transverter. Due to an oversight on his part, he had forgotten that his 9cm transverter is in fact a G3 DB6NT design and thus has LO PLL locking built in. As a result he passed the extra kit on to myself.

  

June 2016:

Wow! How technology has advanced. No offence to CT1DMK and VE1ALQ who developed the CPLD board on the left. This is the PLL board used to lock the LO in my 9cm transverter to my 10MHz GPSDO. The board, dated 2007, is roughly 6cm square and continues to give me good service.   

Steen Nielsen, OZ5N’s Auto-PLL board, on the right is a real advancement in technology. The principle is identical, however advances in technology have simplified the implementation such that the PCB measures a mere 2cm x 3cm.