Topband: Rejuvenating WW2 vintage roller inductors?

[George Stewart (VK5ALS)]

Hi topbanders,

Has anybody successfully rejuvenated the type of roller inductor that
was found in WW2 transmitters? The ones I have are wound on a 2 inch
diameter ceramic material and there are 36 turns over a length of 5.25
inches the wire used is 1/8th of inch in diameter and was originally
silver plated.

A while ago I cleaned a similar inductor using a contact cleaning spray
which in retrospect was not very smart as it would probably leave a film
of conductive lubricant between the turns.

Would the type of ceramic used handle being steam cleaned with a small
domestic steam cleaner? Another idea that passed through my mind was to
put it in the dish washing machine without the normal dish washing
powder as I have seen what happens to a silver spoon if accidentally put
for a normal wash.

What about resilvering the wire when all is clean? I have never tried it
but from memory a small DC voltage applied and using spent hypo for the
source of the silver may work??

Final question: What is the Q of such coils? If I want an efficient base
loading coil would it be better to establish what value of inductance is
needed using a roller inductor and then to wind up such a coil with a 2
or 3 inch diameter air wound with the approx spacing of the winding
having the same diameter as the wire used?

Could respondents please e-mail me direct at ggstew at bigpond.net.au and
if necessary I will summarise the answers for inclusion on the listing.

73

George/VK5ALS

E-mail: ggstew at bigpond.net.au