[Amps] 160m mosfet linear amplifier problem with ferrite cores

[Rob Stampfli]

On Sun, Apr 18, 2010 at 08:00:49AM -0700, sasas asasas wrote:
> i think that the proper material is 43 or 77 for frequences between 1-2mhz.

When I was experimenting with common mode chokes on 160m and 80m,
I tried type 77 toroids, and although they worked quite well, they
overheated very easily.  Type 43 toroids, although spec-wise seemingly
less desirable at these frequencies, worked well and were capable of
handling a lot more power before overheating.  I didn't have ready
access to any type 31 material, although it looks good on paper.

FWIW, for a very good treatise on the subject:

http://audiosystemsgroup.com/RFI-Ham.pdf

YMMV,
Rob / KD8WK