Jeff wrote:

Hi,
Im confused regarding the choice of iron powder toroid for a 7Mhz high pass
filter. I need to use a small size (T68) toroid. For the freq range, some
reference texts say T68-2 is the one, others say T68-6" grade. I see
differing "best Q range" specs for the 6
grade.....2-30Mhz......10-50Mhz...etc.
Have similar need for 20Mhz LPF, but assume "6" is really the choice there.
Any suggestions as to the relative differences and reasons to choose between
grades 2 and 6 for the HPF in T68 size?
Thanks,
JEFF


As far as I know, 7MHz is on the border between using one mix or the
other. You'll see different Q's because details of winding, wire choice
and mounting will affect Q, as would use of a core from another
manufacturer (I don't know if anyone other than MicroMetals uses that
system, but if they did I wouldn't count on it being standardized).

If you're not going to be hitting it with really high power and if you
don't need it to be highly resonant I wouldn't worry too much. If
you're going for an engineered solution then you should make a number of
"identical" coils and test them; just make sure that the coils you make
are representative of what you'll be manufacturing.

--

Tim Wescott
Wescott Design Services
http://www.wescottdesign.com