[Boatanchors] HFS Coils - More Thoughts

[Cal Cotner]

      I doubt that one can really calculate the needed inductances  
because of the effects of parasitic reactances at the higher  
frequencies that the HFS covers.  N7RK alluded to that in his  
response.  The easiest thing might be to use a counter to check the  
oscillation frequency of the LO as you tune across the bands.  But  
remember that counters are capable of much higher precision and  
accuracy than was available to the National factory in the late  
1940s.  Also, I confess that I don't know if the HFS uses high side  
or low side injection for the LO.
      I wish you the best of luck with your HFS restoration.  I'll go  
back and take another look at the B and C coils in particular to see  
just how close the turns are.  I think the A coil is just a single  
loop of strap.  I'll also take a look at the higher frequency coils  
in my NC 1-10A to see what they look like.
Cal K4JSI