Band-Pass Filters for HF Transceivers such as 7 , 14 , 21 and 28 MHz.
A parts diagram for the filter components. All inductors can be wound on Amidon or Palomar T-68-6 toroids, although larger T-80-6 toroids toroids may be used. I used with no. 20 enameled wire and used silver-mica capacitors in all the filters. for capacitors 500 V or more if possible.
Credit : ARRL
Special thanks : HS8JYX , E22RBV