[Elecraft] OT- DC-DC set up converter

[Johnny Siu]

Hello Elecrafters,
 
As you may be aware from my past postings in this mail reflector, I am not a radio man by profession. Therefore, I would like to seek your advice on the construction of an EMI filter.
 
In the junk box, I find a 2.5A, 12v to 15v DC-DC converter previously used to power up my notebook while I was in my car.  I have tried to use it with a 11.1v 3S LiPo cell to power the KX3.  Well, I can get 12 W out from the radio.  However, as expected, the RFI for this primitive DC-DC converter is terrible.
 
I open up this Chinese made DC-DC converter.  The input and output capacitors are 2200uf and 1000uf respectively.  The circuity is simply based on the IC RT34063a + a power transistor + a few resistors.
 
My question is how I can eliminate the RFI generated from this primitive DC-DC converter.  Will an EMI filter be useful in this case?  If the answer is positive, can I build an EMI filter myself?  What is the circuity of an EMI filter for this case?  Where can I get the reference?
 
Thanks for your help in advance.

TNX & 73,


Johnny VR2XMC