what awg wire did you use on the fil. choke?
#14, there is 16A of current.
The choke Carl made is probably a better way to go. that 7.5 inch 1/2 inch diam. material 31 rod is available from Amidon; maybe other sources too.
There are no 31 rods, they are 61 and 33 only. I have both here in 4" and 7 1/2" way cheaper than Amidon.