The filters shown on this page are out of the ordinary.

The filter in the top left picture has no package style designator. It is taller that the standard "FA" style filter and will plug into the "FA" slot. I have yet to plot the band pass for this filter.

The filter bottom left is a "H" style package very similar to the "J" style. The "H" has soldier pins. I removed that unit from a circuit board cleaned the pins and plugged it into a 75A-4. It is a 500HZ filter and works great.

Top right filter is a R-390A filter fitted to plug into a 75A-3. It works.

The discrete component filter to the right is OK for AM on a 75A-3. Input 820 ohms, .01 micro farad, output  750 ohms.

The bottom right is a home-brew 13 kHz filter for the 75A-4. Hi Fi AM. Sounds great.