[TenTec] 564 9 mHz Filters

[Bob Good]

I just purchased an Omni VI Plus (564) and I am looking to fill my "N-2" 
filter slot.  I have a 1.8 mHz TT filter in N-1 and the full complement in 
the 6.3 slots.  I am 90% cw and have operated a Omni VI (563) for 17 years. 
I want a 500 Hz filter in this slot.  In your opinion should I purchase the 
TT 217 or an "Inrad"  filter?  Roofing filter is a term I have yet to learn. 
Your thoughts would be appreciated.  Any help for the OM?  Thanks  Bob K4BG 
k4bg at planters.net