Local Oscillator PLL upgrade for
DB6NT MK2 13cm Transverter.
Page 2

It is probably a safe bet that the board was designed with the layout of the 13cm transverter in mind!  Again, no disrespect to CT1DMK and VE1ALQ; what distinguishes this design is the fact that initial configuration is completely automatic and it can handle a wide range of Local Oscillator frequencies without the need for any preset links.

The heart of the design is a PIC12F1840 8-bit microcontroller crammed into an 8-pin package, in this case SOIC (surface mount). The actual PLL component is an Analog Devices ADF4002. When configuration is initiated, the microcontroller measures the frequency of both the reference and the local oscillator. It then calculates the two divisors such that the resulting quotients are theoretically identical. These divisors are used to preset the reference and N-dividers in the ADF4002 and the resulting output is used to tune the transverter crystal oscillator by way of a (supplied) varicap diode. A minimum amount of modification to the original transverter is required.  The hardest part was fitting the SMA connector (not part of the kit) for the 10MHz reference.   

Once lock is achieved for the first time, the settings are automatically stored in the CPU … thereafter, lock is obtained almost instantly as long as the GPSDO reference is locked.


More information (price etc.) on the OZ5N Auto-PLL can be found here.