Hi Daniele,
Am 27.09.2011 17:15, schrieb Daniele Tincani:
Hello Stefan,
> but maybe the Q is
reduced by the aluminium shield!
Do you
think the aluminium could be the problem or the distance between the
coil and the core?
The wire shouldn't wound directly on the rod. I have a PVC tube above
the rod and so the wire is in a distance of about 3 mm to the rod. I
used litz wire and got a Q of 485...
I could
replace the aluminium tube with a plastic tube, if shielding is not
necessary, but this would not improve the Q if the problem is the gap
between the coil and the core.
Just experiment what is the best solution. But the aluminium shield -
if used - should be thin and can be applied above the winding in some
distance. I know you have much QRM at home so probably an E field
shield makes sense here. Anyway you will be bothered by the local
magnetic QRM of course.
I personally think that a shield is not necessary if you are /p and far
away from man made noise. Then, a higher Q helps more than the shield
and a Q of 30!
> Are the rods
galvanically separated from each other by a thin plastic tape? What
type is the ferrite material?
Yes I
put two layers of plastic tape on tips of each rod. The ferrite
material is russian MU400HH.
Fine! I also use the same ferrite type and 55 turns. Your cap is surely
the best what you can use. So shorten the wires between L and C and
measure the Q on 137 kHz. If it is still in the range of 30, i assume
the shield causes high losses.
Another idea: There is some conducting spray available. Maybe this can
help here? No experience with that, just a spontaneous idea...
http://it.farnell.com/_/kontakt-chemie-emv-35-200ml/rivestimento-conductive-emv-35/dp/220115
73, Stefan/DK7FC
