Hello  expert LF'ers!

The  centre  toroid  of  my  three  toroid  LPF heats up on the longer
transmissions  like  WSPR15.  I  have  added  a  small fan as a crutch
(thanks  N1BUG!) but I guess that's a crutch for inadequate hardware. I
was  wondering  whether  instead of buying a larger toroid, which seem
only  to  be  available  from the US at high cost, I could wind an air
cored  coil  of  similar  inductance. But I am unsure whether it would
have the required "Q" factor. Your opinions please? Thanks,

Also  I  am  wondering,  looking  at the Micrometals site, whether the
current -2 material can be bettered by using -3 material?

http://www.w1vd.com/LPF.pdf

and info on frequency range of these cores is at: http://toroids.info/

  

-- 
Best regards,
 Chris                          mailto:[email protected]