[R-390] R-390A stuck slugs

[Jacques Fortin]

Karsten, look at the picture I sent. 
The tool for the bottom slugs have a shaft thinner than the head. 
And again, the hex opening of the slugs is 3/32
of an inch, so 3 divided by 32 Times 25,4 = 2,38mm. 
Remember also that the IF transformers have to be staggered-tuned. 

Le 20 avr. 2025 à 10:13, Karsten Simon via R-390 <r-390 at mailman.qth.net> a écrit :

Jaques,

·         My hexagonal socket wrench for the tuning slugs is 2,6 mm wide
(distance between two parallel planes measured with micrometer). Apparently
same size as hex holes in the slugs of my 51S-1 receiver. However, you name
2,38 mm instead of 2,6 mm (??).

·         Wrench manufacturer is German firm Bernstein, renown maker of
precision radio/electronics/mechanics tools. Bernstein type is 1-525.
Material is all plastic. Hex head is glued to shaft, shaft is probably some
special tough material. Wrench shaft is somewhat springy, probably to
prevent excessive torsion.

·         Wrench fits precisely but tip is too short. Does not reach bottom
slug.

·         Top slugs in Z503, T501, T208 are free. Top slugs in T502, T503
are stuck.

·         Bottom slugs unknown because tool is too short – no probing
possible.

·         All tuning slugs are undamaged.

·         Tried drops of WD40 on T502 top slug (->Internet). No success
after 24 hours. Still stuck.



Questions:

·         How can I loosen the stuck tuning slugs?

·         Where can I buy a suitable socket wrench (short 2,6 mm hexagonal
tip, long thin shaft)?

·         Or should I simply skip alignment of these inductive components?
Manual says normally no readjustment needed.



Happy Easter + 73 from Moenchengladbach/Germany,

Karsten







-----Ursprüngliche Nachricht-----
Von: Jacques Fortin [mailto:jacques.f at videotron.ca]
Gesendet: Sonntag, 20. April 2025 04:50
An: 'Karsten Simon'; r-390 at mailman.qth.net
Betreff: RE: [R-390] R-390A stuck slugs
Wichtigkeit: Hoch



Karsten, can you give more precisions about the "stuck" slugs ?

Are you talking about the top or the bottom ones in each of the IF
transformers, or both ??

Are the slugs seems to be cracked ?

Is the slug of Z503 moving ?



Which tool are you using ?

The hexagonal openings of the tuning slugs are 3/32th of inch in size

(2,38mm)

Maybe that if you use metric size drivers (2,0mm ?) that they just "turn" in
the cores hex openings without moving those.

See attached picture.



73, Jacques, VE2JFE in Montreal

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