Justin:
There is something to be said for fixing the radiuno.
The resulting signal is much more stable than an
"ordinary" analog VFO.
That being said, there is nothing wrong with using an analog VFO.
Designing a very good one is always one of the great challenges
faced by any ham.
The BITX40 came originally with an analog VFO -- it is easy to
"reinstate" it if one does not wish to use the raduino. Look at the
original circuit diagram and you will see the VFO and BFO around
the center. The VFO is Q8 and Q9 and associated circuitry; the
BFO is Q10. Note that there is a place for a DDS connection.
This is where the raduino connects. If that connection is not made,
one merely has to make sure the rest of the circuitry is in place.
Usually L4 and D0, possibly C91 and C92 are disabled. It is a
simple matter to put them back to active status.
It is also possible (I have not checked this) that the newer BITX40 rigs
come with the analog VFO already enabled, and will work just by wiring them
up. This VFO is known to be somewhat drifty, and one can think of ways to
make it better, e.g., replacing C91 and C92 with known C0G units. One can also
experiment with the cap values and see what effect that has on the rig. Etc.
The files section has diagrams of the earlier rigs, such as the BITX v.3. These
had analog VFO'S as well and are quite educational to look at and copy.
As always, if you don't know the answer, ask the question...that is always the best
first step. The files section of this list is a very rich resource. Look it over well.
Check out the magnificent work of F8VOA.
Hope this helps.
john
AD5YE
