Forte RF Amplifier, LPF
LPF board scehmatic
You can also visit a GitHub repository to access KiCad project including gerbers, BOM, software and more: link.
How to make inductors?
Below table lists bands covered by the LPF board. Second column indicates the type of mathematical polynomial used to calculate the filter's LC values. Third column indicates type of toroidal core used. Notice that all HF bands use ferrite material for the core while 6 m band uses air.
Columns L1, L2, L3 show the value of inductance for each coil as well as number of turns (15T = 15 turns of wire). I have used 1.2 mm enammel wire for all my coils. For the 6m band I have designed a former that can be eaisly 3D printed resulting in an accurate inductance. You can download model of that former from my github (link).
| Band |
Type |
Core |
L1 |
L2 |
L3 |
| 160 |
Spherical |
T-106-2 |
3u 15T |
3u 15T |
NA |
| 80 |
Cheby7 |
T94-2 |
2.5u 17T |
2.8u 18T |
2.5u 17T |
| 40/30 |
Cheby7 |
T94-2 |
1u 11T |
1.2u 12T |
1u 11T |
| 20/17 |
Cheby7 |
T94-10 |
0.6u 10T |
0.7u 11T |
0.6u 10T |
| 15/12/10 |
Cheby7 |
T94-10 |
0.317u 8T |
0.41u 8.4T |
0.371u 8T |
| 6 |
Cheby7 |
Air |
3D printed Form |
