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

[Craig Heaton]

Hello Alan,

The variable IF section has two (2) thingies which hold three slugs, each.
The RF section has six (6) thingies which hold three slugs, each. The IF
slugs are the same, but are different from the RF slugs. All RF slugs are
the same.

With a dental pick, short piece of solid hook-up wire with a hook on the
end; release the two springs holding the bar which holds three slugs. Remove
and set off to the side. Do not move any bar to a different location! With
the thingie (bar) removed it is possible to remove three IF or RF
transformers. Remove one at a time, don't find a new location for any
transformer. 

The IF transformers only have a wire wound core. The RF transformers have
silver mica caps & a wire wound core. Each have trimmer cap(s). 

If picking belly button lint is your thing: Over the years those trimmer
caps have been spun in circles several hundred times. A little metal tends
to rub off where it should not. Each transformer has two tabs which hold the
cover in place. Those tabs can be pushed inward and cover removed. Then the
end of each trimmer caps is held in place with a keeper. It, the keeper, can
be slid off with a small screwdriver. The top section of the trimmer then
can be removed and the offending metal can be wiped off with a q-tip and a
drop of DeOxit or cleaner of your choice. Each transformer has a single
Philips screw that holds it in place. After the slug(s) are out of the way,
a #1 philips screw driver lowered down the center opening of the core should
do the trick.  

Of course, this means starting from scratch in peaking the variable IF & RF
section. 

The entire shooting match which hold all those bars, slugs, etc. seldom
needs to be removed. Bearings are on the ends of those thingies (bars) which
holds three slugs. There are several screws on each threaded slug holder.
These can be loosened so the slug drops straight into the center of the wire
wound core.

DO NOT USE ANY LUBRICANT ON SLUGS or INSIDE OF CORES!

On some RF sections, depending on maker, clearance is tight. Transformers on
the adjacent octave might have to be loosened to obtain enough clearance to
remove the wanted transformer. 

Hope this helps.

Craig,



-----Original Message-----
From: R-390 [mailto:r-390-bounces at mailman.qth.net] On Behalf Of Alan Victor
Sent: Thursday, October 16, 2014 5:36 PM
To: 390 list
Subject: [R-390] Ferrite rod-slug and rack tuning assembly

Question on the ferrite rod slug and rack:

I have seen pictures of the slug rack removed. However, I don't see in those
pictures the bar that runs across the rack with roller bearings at each end.
Am I missing soemething? It appears to me that when the ferrite rod and rack
assembly are removed,  that the bar and roller bearing assembly would all
come out together. I anticipate cleaning the roller bearings after removing
the rack for each band.

Thank you,

Alan
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