[R-390] Filter repair

[quartz55]

Hmm, I may be on to something here.  I 'repaired' a FA type filter, and just to test it in my test setup, I shoot 1vrms (2.8vp-p) into the 'repaired' filter and measure out of the thing .12vp-p (.042rms) doing the math, that turns out to be 27db. I haven't checked the BW, but it sure starts to cut off at about 1K high.  I've got one of the 4K 390A filters about to be ready to test, I need to tack the end caps in the tube so they don't fall out.

How does this test setup look?  I've got the 50 ohm monitor output going to the Pamona box with a .1uf and a 100K ohm in series, a 70pf variable across the filter and on the output the same 70pf variable and a 100K resistor feeding right into the scope input with the clip leads.  It seems to peak up fine.  I haven't got the grounds set up right yet, but that will come. I'm not sure how many db I can measure for loss anyhow.  The proof will be in the pudding.

http://i251.photobucket.com/albums/gg287/DogTi/R390A/FILTERTESTSET_zps3d02da99.jpg