630m gang, Fritz asked me to forward this to you because he seems to be having problems posting to the 600mrg list today....

February 16, 2023

Gentlemen:

     Ferrite makes excellent small-signal inductors
and chokes (e.g., for a receiver).  It also is the
better material to use for transformers in power
amps and tuners.  77 MF, 43 HF, 61 VHF.

     However, it is unsuitable for high-power
inductors and chokes because it saturates.  Once
saturated, the inductance is basically that of an
air-core inductor of the same size and shape.  You
can see this effect easily by measuring the inductance
while passing dc through the winding.

     For transmitting applications, you need to use
either air-core coils or powdered-iron toroids.  I
used Micrometals T130-6 for fine-tuning of my
500-kHz antenna tuner.


73, Fritz, W1FR

Frederick H. (Fritz) Raab, Ph.D.
GREEN MOUNTAIN RADIO RESEARCH COMPANY
1183 Jonquil Lane
Boone, Iowa  50036  USA
Tel:  +1 (515) 275-2141
Cell: +1 (802) 598-9527
E-mail:  [email protected]
Web:  www.gmrr.biz