[R-390] 4kc filter

[Flowertime01 at wmconnect.com]

Been following John KC2FXE's R-390A problem 'on the air'...don't think he'll 
mind if I jump in here. The filter works but develops sufficient leakage to 
drag down the agc when the radio warms up. As it cools off the leakage 
problem goes away.

Jay W1VD

----------------------
We know the filters when built had some foam insulation in them.

We also know that after all this time that foam has turned to gunk.

If your filter happens to have an air leak in the solder joints on either end,
then it can attract moisture. The gunk can also move around, change size with 
temperature, change conductivity.

Any and all of this can cause circuit problems.

We also know the filters can be unsoldered, cleaned, repacked and reassembled.

All good work worth doing if you have a filter giving you problems.

Any old filter not yet rebuilt will have the same gunk inside.
After shipping and handling, there is no assurance that it will work OK.
Cause that gunk may do any thing while in shipping.

If you have to pull and replace a filter you may as well install a filter 
that has
had the extra effort applied to replace the packing foam.

You can do the rebuild the filter your self, buy one and send it out for 
rebuild or buy one that is rebuilt. YMMV and thus your choice.

Roger AI4NI
-------------- next part --------------
An HTML attachment was scrubbed...
URL: http://mailman.qth.net/pipermail/r-390/attachments/20081118/8952cab4/attachment-0001.htm