[R-390] Collins R 389 PTO

[2002tii]

Roger wrote:

>Down the other path, what are the chances of mixing core stuff and epoxy to
>make a new core?

Not a chance.  For little repairs, yes, but not a whole core (or even 
a decent chunk of one).  The thing to do is find a lump of the right 
ferrite that is bigger than the core, then machine it to 
size/shape.  If someone shipped a good 70H-1 core to Magnetics, they 
could probably help to reverse-engineer it.

>Then we would have to do a new coil form and wind a coil.

The coils and forms should be salvageable, even if they're 
broken.  If not, one could relatively easily duplicate the coil and 
form if they had a good one to copy.

>I cannot imagine how many test coils would need to be wound to get the
>inductance and linearity close enough to be usable.

I wouldn't dream of trying to re-engineer a PTO that would meet 
original specs.  But I would copy whatever is necessary to repair one 
to the original design.

Best regards,

Don