The schematic does say ~50 T of #34 SWG wire on a stacked T-37-6 core.
First, SWG is not the same as AWG, so your #34 may not be quite the same size as called for. The size difference is small, but it adds up.
Second, yes, using a stacked core does make quite a difference.
Third, there is no reason not to change to a T50-6 or T67-6, and wind on that core. You are aiming for a certain inductance and it dies not matter a great deal how you get there; what changes is the Q of the circuit: Try 50 T on a T50-6 core. It will probably be a bit too much and the frequency generated will be a bit low. Take off a few turns at a time until you hit the right range, then evenly distribute the turns around about 2/3 of the core -- this will be L4.
Alternatively, you can increase the capacitance of the tank a bit to lower the frequency as well. Use a single layer coil with the T37-6 and fiddle with the capacitance as above. There are both advantages and disadvantages in a VFO to having the tank circuit inductance weighted or capacitance weighted. Sometimes it is a matter of personal choice.
In other words, unless there is an absolutely compelling reason not to do so, one can alter the tank circuit components in the oscillator pretty much at will, provided the end result is the same. Experiment. YRMV (all over the place).
john
AD5YE
---In BITX20@..., <marktbaldridge@...> wrote :
Just double checked. It says 50 turns in the construction manual, 52 on the schematic.
See this folder, and file bitx3b.sch.pdf
Now, the schematic does say on a stacked T37-6 core. Would two cores stacked make more or less inductance? More inductance would lower the frequency, right?
