I wanted a better feel tuning on my Bitx20 so I decided to convert it to varactor tuning VFO with a 10 turn potentiometer. I used the MVAM109 to replace the 1N4752A diode on the board. I was able to connect the 10k 10turn pot to the fine tuning post. I added a 33pf cap where the coarse tuning pot connected. It was trial and error but I did get the right combination to put me in the frequency range needed.
I followed the schematic provided by kc0wox but made changes to fit my project, you can find it here: http://www.golddredgervideo.com/kc0wox/bitx20amods/varactormod.htm