[R-390] R-390A BFO

[Flowertime01 at wmconnect.com]

Bill,

I just have not been into that can since about 1970.

The BFO shaft should have threads on it so that it moves into and out of the 
BFO face plate assembly as the shaft is turned. This is why there is a bellows 
coupler between the BFO extension shaft and the BFO can assembly. 

The slug is threaded on the inside. The shaft is threaded on the end in the 
BFO can and coil. The two parts go together and are glued together. You glue 
has broken loose.

As the shaft turns it should screw in and out of the BFO can and move the 
slug in and out of the coil The slug spins with the tuning shaft inside the coil.

It sounds like your slug has come unscrewed / unglued from the shaft. This 
can happen because the BFO does not have a stop washer under the BFO pitch knob. 
Or the knob is set to far forward and thus the skirt tap does not catch on 
the stop washer.

First the shaft was run to minus BFO pitch until the shaft screwed out far 
enough to pop the slug off the end of the shaft. Then the shaft was run to plus 
BFO pitch until the shaft drove the slug to the bottom of the slugs tube.

You may need to do some more disassembly just to clean some bit of broken 
slug fiber out of the slug so the shaft will run back in to the slug cleanly.


As the shaft and slug are inside the coil core you may have to disassemble 
the face and shaft from the coil to get to the slug and end of the shaft where 
you need to glue the two parts back together.

If you can get the back end off the assembly you may be able to shake the 
slug out the back end of the coil tube, clean up the parts and glue the slug back 
on to the shaft.

Run the BFO shaft out as far as reasonable.

Thump the BFO, shaft first into the bench and get the slug to move away from 
the far end of the assembly.

Pry the slug to toward the shaft a bit. Turn the shaft and try to get the 
slug to re engage the threads on the BFO shaft.

If at first you do not succeed then try some additional disassembly until you 
can get things to go back together.

If you break it for real, post a note here and ask if someone will sell you a 
good used BFO can. Someone likely has one in a parts deck.

If you fix it then post us some details as to what it took to get it done.

Roger AI4NI   </HTML>