[R-390] AGC/filters

[quartz55]

Just to add to the confusion.  The module I was repairing the filters in, I installed the repaired 2K and 4K filters and the agc line in that IF was measuring around 50Meg (pin 6 J512) with my Fluke 189.  The good module measures in the hundreds of Megs. I'm getting some confidence that this 189 will measure good Meg resistance without the need for high voltages.  So something's amiss.  Started removing resistors and no results, it appears that when I installed the FA filter in the 2K tube, one of the tabs hit the plastic base inside the filter, discovered after removing the end cap, hope I can get it back together I don't have another 2K filter, I'm going to take the dremel and see if I can grind off the plastic so I can install the cap without the wire tab hitting anything, that brought the resistance from that coil to ground to about 50 Meg.  The 8K filter is also around 60Meg, so it's apart now being repaired, just lots of goopy stuff from the old foam.  Hopefully this will bring the agc R back up to the hundreds.  We'll see.

I'll also do an exposé on repairing filters that only have isolation problems, I didn't do much to the 8K filter other than take it apart, remove the goop and I've got some hardline foam glued to the thing and ready to install back in the tube when the glue dries.  This only took me about 3 hours but I had a bunch of stuff ready.  The proof of the pudding is going to be soldering the #40 wires back on the end tabs.  The 16K filter coils are still measuring over 300Meg to ground.  You can only do this after removing any wires to the coils.  When it's in the circuit, you really can't tell anything.

Dave
N3DT