Has anyone ever tried using big crossover coils used for speaker building for RF chokes instead? It dawned on me many of them are exactly 2.5mH. I came across the ones below and they are 2.5mH using AWG18 wire and they would sure handle the current. They are air wound and I don't really see any reason why they wouldn’t work in RF circuits too. Of course, they are not pi-wound, but I don’t think it would really matter and their self-resonate point should still be well below 1.8MHz. You could make them pi-wound though by using 3 of them slipped over a wooden dowel and connecting them in series for 7.5mH total. These things are only $11 each and they also have a bigger one with AWG14 wire that handles 750W for $28. 2.5mH with AWG18 wire I think these would work really well for the 2nd choke in series with the cold-end of plate chokes in big linears, at the output connections in antenna matchboxes, and as corona discharge drains at the base of vertical antennas to ground etc. The only issue I can see might be HV breakdown if too high of a plate voltage is used, but they should have no issues for the other 2 applications. 2.5mH with AWG14 wire .