[R-390] Filter Repair

[quartz55]

I got the early shiny 4K filter repaired.  I had to use a coil from the broken 2K filter I had since one of the coils went bad.  I dropped the magnetostrictive wire and couldn't find it so I used the #34 nickel wire I have and it didn't take long to fix.  The older style filters are actually easier to work on, they are in a metal structure with clips attached to the end caps so I can put the thing together in it's structure and push the whole thing in the tube as an assembly without messing with the end caps and wires.  The response is not great, 8 dB ripple but it certainly is a 4K filter.

This makes the second 4K filter I have fixed that's extra.  If anyone needs one let me know.  I can't guarantee these things, but I won't hurt you too much.  It does take a day to fix them, it was raining all day today anyhow.

Here's the response.  Interesting all the 4K I have show a rise at the high end.  This one is very sharp on the skirts, but I'm not sure it's the way I measure now with 20 dB more in/out isolation. 

http://i251.photobucket.com/albums/gg287/DogTi/R390A/R390A%20Filter%20Repair/4Kshinyresponse_zpsf882abe8.jpg

Dave