[R-390] Ferrite rod-slug and rack tuning assembly

[Tisha Hayes]

I have never seen any sort of binding caused by the roller bearings on the
slug carrier guides. They do such a minor amount of movement up and down
when tuning ( less than an inch each ) that unless someone has done
something physically damaging to the slug carrier guides they seem to last
forever.

Where I have seen damage to the slug carriers is when a radio was left
sitting around without the Utah plate that covers the RF/IF decks.

Those little springy pieces of metal attached to each slug are sort of
fragile. If you do pull the slug carrier guide free (and that is where you
unload those springs on the end that keep the carrier pulled down tight
with the brass cams) you need to be careful to not break off a slug.

If you pull a slug carrier out of the IF cans and you are missing a slug
(because it has broken off) then you need to pull the IF can and dump out
the slug or turn over the entire radio to get the slug to drop free. You
"could" epoxy a slug back onto it's respective spring, that usually works.
If not you can find a spare slug off of a surplus RF deck and replace it.
Take care to note how far the slug is mounted into the rack (measure the
distance) and try to replicate that insertion length. Because of the slight
changes in permeability of the slug you will end up realigning the entire
band. Just accept that inevitability and move on.

As has been stated, you cannot use an RF slug in an IF spot (or vis versa).
Also there may be some differences between slugs in certain spots (I am not
too sure about that). The slugs are pretty sensitive to lots of things, too
much cleaning, the use of lubricants or solvents, moisture, etc...

The most I have ever done to them is to wipe them down with a little bit of
isopropyl alcohol and to clean out the RF/IF transformer bore with a cotton
swab. If I have one that scrubs against the wall I will dust it with talc
(baby powder, extremely tiny amount). The other choice is to try to bend
that springie thing that the slug is attached to and that is a very quick
way to break it off. I found one RF deck where some individual (use
unspeakable and impolite phrases here) used oil in the transformers. It
made a big mess and turned things into a dirt magnet.

-- 
Ms. Tisha Hayes. AA4HA

*""It is not because things are difficult that we dare not venture. It is
because we dare not venture that they are difficult." -Seneca"*