Showing posts from April 13, 2014

Bitx3B VFO

The FLL frequency counter used for Bitx3B may sometimes not read the frequency from the Bitx3b VFO stage, the reason being the VFO buffer has a low output kept for the stability of the VFO. It is observed that in some cases the Freq counter does not read the freq and some times it does, some transistors may have a higher gain and some lower as the brand is not same for all the kits we supply the 2n3904 transistor. Due to the different gain of transistor the issue of FLL not reading the freq arises.

 The solution is simple without disturbing the VFO capacitors value's we just need to change C13 in the FLL Freq counter from 22PF to 47 PF. I tied this and it works fine. Here is a picture of FLl Freq counter with FLL C13 that has to be changed to 47PF

The second issue of VFO Freq Stability. T50-6 was tried on the VFO of Bitx3B with around 50 turns. Kindly adjust turns to reach 4.MHZ reading on the VFO, you may have to wind turns as per need, if you connect the FLL freq counter yo…