Posted by
Geoffrey Mackenzie-Kennedy-3 on
May 03, 2012; 2:32pm
URL: http://elecraft.85.s1.nabble.com/Loading-inductor-Question-tp7513850p7523847.html
Ken,
When you do the research and math, worth bearing in mind that powdered iron
(and ferrite) cores can generate intermodulation products. Usually this
problem will affect the "receive" performance of an antenna matching
network, or a receiver's front end filters, if exposed to strong signals
e.g. SW Broadcast.
The root cause of this IMD problem can be traced back to the magnetic flux
generated in a core by the incoming signals. The flux density is
proportional to the applied voltage (vector sum of incoming signals), and
inversely proportional to the core's cross section (area), the number of
turns and the frequency. Thus the number of active turns should be as large
as possible, the loaded Q of the network should be kept low, the core's mu
low in value, and a large core used.
Sorry to be late with this comment.
73,
Geoff
LX2AO
On May 01, 2012 at 15:23 +0200, Ken Alexander wrote:
Many thanks for all the helpful responses! I do have many toroid cores in
stock already but almost all are FT-50-xx and T-50-xx. I'll do the research
and the math and give it a try when antenna building season arrives. It's
still a little too cold and wet for that at the moment.
73 - Ken
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