[R-390] Filter Repair

[quartz55]

I've pulled apart an early shiny 4K filter. I heated the label with the heat gun and was able to pull it off without messing it up except the glue stayed on the tube, but at least the label is intact. I thought from other articles that the end caps were strapped together, but unfortunately that is not the case, at least for this filter.  I hung the filter by the top end cap lugs and tied a 10 lb. weight to the flanges, hoping to pull the tube off, but all it did was pull the top end cap off, breaking the coil wires in the process. One broke at the terminal and the other broke at the bobbin.  However, I've repaired that, there was enough still on the bobbin to repair.  The innards of the filter seem much better made than the later ones.  See the pics, no foam goop.  The assembly is held in a metal circular bracket by 2 rubber grommets that are still in good shape.  The other problem is the magnet fell out of the top side, that can be glued back in place, not sure about the orientation N/S or if it's even important.  The biggest problem is the magnetostrictive wire fell out of the bottom side, but I still have it, if you look carefully at the pic, you can see it.  So it looks like I'll be trying to weld the wire back in place.  If I can accomplish that the filter may work again.  I'm going to try much lower voltage because the last one I tried, I melted it and had to go to a #34 nickel wire.

http://i251.photobucket.com/albums/gg287/DogTi/R390A/R390A%20Filter%20Repair/4Kshiny_zps42290a34.jpg
http://i251.photobucket.com/albums/gg287/DogTi/R390A/R390A%20Filter%20Repair/4kbottommagnetowie_zps3839bed4.jpg
http://i251.photobucket.com/albums/gg287/DogTi/R390A/R390A%20Filter%20Repair/4kshinytopmissingmagnet_zpscf3cd0bf.jpg

Other thing I've discoverd is the Fluke will measure conductance in nS. >From 0.1 to 50 nS, 0.1 nS = 1,000,000 MO, 50 nS = 20 MO.  Trying to measure conductance from ground to the coils in the repaired filters, I still can't measure anything.

Dave
N3DT