[R-390] Mechanical Filters

[Flowertime01 at wmconnect.com]

Keith,

The Fellows here on the R390 reflector did a whole series on rebuilding the 
filters
here last year. You will need to look through the archives.

There were even web pictures and everything when we got done.

You can fix the filters if you can solder, We can help.

In side the filters was some sponge packing that held things in place.
Over time the sponge packing has turned to sticky stuff.
This has left the filter part hanging on the very small wire leads.
Over time the bumps and gravity will cause one of the wires to break.
Thus the filter goes from band pass to full stop.

The procedure is to remove filter from the IF deck.
Using a larger solder iron the ends are heated and the whole inside will slide
out of the round sleeve body of the filter.

Use care the wires are short. 
There are three parts inside the sleeve.
The two end caps and the filter part.
The three items are coupled with fine wire.

Heat one end and pull it free.
Turn the assembly over and do the other end.

With both end free, undo the wires.

You can then get every thing apart and clean up the solder joints.

Then you can put it all back to gether.

Some packing foam can be cut for new spacers.

Hang the sleeve with wire through the mounting flange holes.
Tie a second wire from the end terminals.
Hang the sleeve from over head.
Pull down on the second wire.
Take care not to catch hot solder on the human body.
Apply heat to the joint.


You can clean up the sticky stuff and do a wire repair.

The guys at Fair Radio have gone so far as to do a complete rewind on the
input and output coils. Install new packing and do a re solder.

Others have just done wire fix and re solder.

I am still rebuilding my retirement home and have no bench unpacked and set 
up yet. So I am not doing repairs my self.

I hope you receive some mail from other Fellows. One was trying to develop a 
small market to do repairs and exchanges.

Good Luck

Roger AI4NI

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