Replacing a through hole inductor with a SMD inductor?

F

freddysilver

New Member

• Apr 26, 2015

• #1

This should be a very basic question. I searched enough but was not able to find a direct answer. Can i replace a axial through hole inductor of a filter network in a RF circuit with a SMD of same value? Circuit specifies a 0.33uH axial molded inductor which is very hard to find now. Please help.
Cheers!

 

dr pepper

Well-Known Member

Most Helpful Member

• Apr 26, 2015

• #2

Yes you can, there are some imporatant specs to pay attention to, one is dc current capacity, this should be the same or higher, and another self resonance, it depends on the application but similar or higher is usually ok.

 

F

freddysilver

New Member

• Apr 26, 2015

• #3

Thank you dr pepper https://www.electro-tech-online.com/members/dr-pepper.100692/

 

Tony Stewart

Well-Known Member

Most Helpful Member

• Apr 26, 2015

• #4

SMD power chokes are far superior in Idc 42A possible.
SMD Signal inductors are far better for SRF.

Is it a power inductor or a signal inductor ? That one is < 1mΩ power inductor.

This is a signal inductor rated for 250MHzand 900MHz SRF
https://www.digikey.com/product-detail/en/9-1624112-3/A103724TR-ND/2731338

 

Last edited: Apr 26, 2015

B

BobW

Active Member

• Apr 26, 2015

• #5

Digikey also has a number of different axial .33µH inductors in stock. No need to buy SMT. For example:
https://www.digikey.com/product-detail/en/9250A-331-RC/M10109-ND/969843
Note: 330nH=0.33µH

The OP said it's part of an RF filter, hence a signal inductor, unless it's part of a high power transmitter output matching network. But, I suspect not.

 

Tony Stewart

Well-Known Member

Most Helpful Member

• Apr 27, 2015

• #6

Unless you specify application details.

Bob's part may do for < 100MHz or affect tuning freq a bit down.

Bourns Part No.
Inductance Q 46 Min. @25MHz
Test Frequency (MHz) SRF = 250 MHz)
9250A-331-RC 0.33 ±10

 

Mosaic

Well-Known Member

• Apr 27, 2015

• #7

The peak Q frequency would matter depending on the gain of the semiconductors downstream. Also whether the inductor is shielded from other magnetic influences nearby etc.
This might help.
https://rf-filter-circuits.blogspot.com/