[HomeBrew] A quick toroid "use" question

[Steven Weber]

>sources.  I can't help but believe that there would be at least some coupling
>between closely mounted toroid coils in compact construction, such as I show
>below with ASCII graphics.

Yes, closely spaced toroids will couple. The coupling between vertically
mounted cores will be minimual if spaced at least 1/2 thier diameter apart.
The best method is to mount them at right angles to each other.  I -- I  

I just tested the filter used in my new four band, Altoids sized rig, which
uses small plug in filter modules. The two cores in the Tx LPF are very
close to each other. Best results are when both cores are vertical and
spaced .2" apart, (T27 cores) or when one core is vertical and one laid
flat. Worse is when both cores are laid flat and the sides actually
touching. But that only results in about 2 dB degergation. Regardless of
how the cores are positioned, the filter still exceeds FCC rules (the new
rules of -41 dBc min), so not concerned. (I'm also glad to see that routing
the input and output of the filter to adjacent pins on the SIP header
didn't cause a problem either)
 

72,
Steve, KD1JV
"Melt Solder"
White Mountains of New Hampshire
http://www.qsl.net/kd1jv/