[R-390] Filters

[quartz55]

Norman,

Thanks for that link.  I'd seen a few links to the filter repair but not that one.  I'm thinking if I need to I could do that.  I'm wondering about the donut that holds the assembly in the tube, seems it should be completly non-conductive, but stiff enough to hold the assembly tightly in the tube.  I'm just trying to think of what would be really good there. Maybe a teflon or delrin donut with some silicone rubber to make a rather press fit into the tube?  I'm not thrilled with A/C insulation tubing, it would probably do what the old stuff does eventually, turn to puckety.

I'm not sure I've seen what the in/out inpedances are for the filters?  I suppose I could find out by hitting them with 455 out of my service monitor and increasing a series resistance until I get 3db or half voltage across the resistor and the filter.  The 50 ohm of the monitor would be irrelevant at that time.  My monitor will only sweep down to 1MHz so it may be a bit difficult to check the response by sweeping.  I could just do it 10Hz at a time.  The monitor is High Stability, so it's plenty accurate.