J
Joerg
- Jan 1, 1970
- 0
Folks,
Designing the umpteenth higher power RF filter here and wondering. Are
there any truly bifilar-wound common mode chokes? Maybe some niche shop
in the boonies makes them? I've been through the usual places such as
Pulse and Gowanda.
I'd need 100uH or more, 1A of (differential) current with 2-3A
preferred, thru-hole would be nice but not required, and leakage
inductance is very critical because of a somewhat sensitive filter
requirement. 300nH or maybe 400nh could be digested but not more.
So far I've always done that with some big double-hole ferrite cores and
coax but this gets old. Mostly because that's bulky, you need 3-4 in a
row because you can't get more that two turns of RG174 through those and
the manufacturers never offer any kind of fastening material. Seems the
issue of having to mount them onto a board or chassis is beneath them.
Plus it's a custom part we have to hand-wind in production and
off-the-shelf would be more desirable.
Commercial ones either have double-chambered bobbins which results in
horrible leakage inductance or they look like this and still have almost
2% of nominal as leakage:
http://media.digikey.com/photos/Murata Photos/51504C.JPG
Insulation strength between the two wires won't matter, there's never
going to be more than 100V and there is going to be a safety shut-off in
case it goes kaputt.
Designing the umpteenth higher power RF filter here and wondering. Are
there any truly bifilar-wound common mode chokes? Maybe some niche shop
in the boonies makes them? I've been through the usual places such as
Pulse and Gowanda.
I'd need 100uH or more, 1A of (differential) current with 2-3A
preferred, thru-hole would be nice but not required, and leakage
inductance is very critical because of a somewhat sensitive filter
requirement. 300nH or maybe 400nh could be digested but not more.
So far I've always done that with some big double-hole ferrite cores and
coax but this gets old. Mostly because that's bulky, you need 3-4 in a
row because you can't get more that two turns of RG174 through those and
the manufacturers never offer any kind of fastening material. Seems the
issue of having to mount them onto a board or chassis is beneath them.
Plus it's a custom part we have to hand-wind in production and
off-the-shelf would be more desirable.
Commercial ones either have double-chambered bobbins which results in
horrible leakage inductance or they look like this and still have almost
2% of nominal as leakage:
http://media.digikey.com/photos/Murata Photos/51504C.JPG
Insulation strength between the two wires won't matter, there's never
going to be more than 100V and there is going to be a safety shut-off in
case it goes kaputt.
