[R-390] R-390A stuck slugs

Sun Apr 20 16:35:57 EDT 2025

Hi Karsten,

I have re-attached the picture.

Tool kit offered by Radio Daze in the US:

https://www.radiodaze.com/alignment-tool-kit-item-tl-align1/

The one you need within this kit is the 0,1” HEX (the white one).

There is several other “Alignment Tools Kits” offered on eBay, but I do not find one with the proper 0,1” HEX variant you need for the R-390A IF slugs.

Except this one: https://www.ebay.ca/itm/283917619073?_skw=radio+Alignment+tool+kit <https://www.ebay.ca/itm/283917619073?_skw=radio+Alignment+tool+kit&itmmeta=01JSADGEXMC20KE69WXW4R3HE3&hash=item421acf0f81:g:WhAAAOSwKVhe6ivG&itmprp=enc%3AAQAKAAAA0FkggFvd1GGDu0w3yXCmi1feMQg%2Fw%2B%2BBq63aZqCzGaGLfCFNT5wURt%2BnNJPAeens6hpwxjGWoIU3sgc6j%2FAuKLRC3wiXMeizhzjFTZfNlorHXgeO3Nw5depMLD%2FOZO2QNIk%2Fpf2dg9GvTYhh%2BJ%2FEuwUD3PNasEZLCibr0t8QMI2AMM6JyVKs9P2iF9Ujxn0vMCCYtn4Q7WjF9hYWDy0fig34TaGGoXXMmKrnIzFSAEMsRmViHQCtn3Mcj6HQgvN45b3CRAV%2FQAMiT6%2F23HfyDiY%3D%7Ctkp%3ABk9SR_7uwc3KZQ> &itmmeta=01JSADGEXMC20KE69WXW4R3HE3&hash=item421acf0f81:g:WhAAAOSwKVhe6ivG&itmprp=enc%3AAQAKAAAA0FkggFvd1GGDu0w3yXCmi1feMQg%2Fw%2B%2BBq63aZqCzGaGLfCFNT5wURt%2BnNJPAeens6hpwxjGWoIU3sgc6j%2FAuKLRC3wiXMeizhzjFTZfNlorHXgeO3Nw5depMLD%2FOZO2QNIk%2Fpf2dg9GvTYhh%2BJ%2FEuwUD3PNasEZLCibr0t8QMI2AMM6JyVKs9P2iF9Ujxn0vMCCYtn4Q7WjF9hYWDy0fig34TaGGoXXMmKrnIzFSAEMsRmViHQCtn3Mcj6HQgvN45b3CRAV%2FQAMiT6%2F23HfyDiY%3D%7Ctkp%3ABk9SR_7uwc3KZQ

Another paradox is that I have about 30 of these 0,1” hex tools, molded in nylon from the ‘70s.

If ever you are not able to procure any, let me know, I will send you a couple of those.

These are like the white one in the 2nd picture.

BTW, using WD-40 on those IF cores is a bad idea, because it can make the core swelling (it’s made of cardboard).

On another hand, I never experienced a problem like the one you have in the 5 IF decks I have (or had).

If you want your unit to behave correctly, you should preform a full alignment.

Never rely on what was performed by the previous owners…

You will have to adjust the mechanical filters trimmers also, input and output.

73, Jacques, VE2JFE in Montreal

De : Karsten Simon <karstenpg.simon at web.de> 
Envoyé : 20 avril 2025 14:23
À : 'Jacques Fortin' <jacques.f at videotron.ca>
Objet : AW: [R-390] R-390A stuck slugs

Jaques,

*	look at the picture I sent

No picture received. Maybe the forum software has deleted it? Pls try again to karstenpg.simon at web.de <mailto:karstenpg.simon at web.de> 

*	The tool for the bottom slugs have a shaft thinner than the head

Of course. Where can I buy such a tool?

*	the hex opening of the slugs is 3/32 of an inch, so 3 divided by 32 Times 25,4 = 2,38mm

Your math is correct. Nevertheless I have just measured again: hex opening is 2,55 mm (caliper). My Bernstein wrench measures 2,57 mm (micrometer). Somewhere I have read about hex opening = 0,1 inch = 2,54 mm. That would make sense („round“ number) and is also pretty close to my measurements 2,55/2,57 mm.

*	Any ideas how to free the lugs in T502, T503?
*	Stagger tuning: should be minor problem once the slugs are free. Or, follow manual and simply skip tuning these filters? Criteria for tune or not tune?

73, Karsten

-----Ursprüngliche Nachricht-----
Von: Jacques Fortin [mailto:jacques.f at videotron.ca] 
Gesendet: Sonntag, 20. April 2025 19:04
An: Karsten Simon
Cc: r-390 at mailman.qth.net <mailto:r-390 at mailman.qth.net> 
Betreff: Re: [R-390] R-390A stuck slugs

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 <mailto: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 <mailto: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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