[R-390] RF Deck Removal and Questions

[Jacques Fortin]

Hi Alex,
To complement Barry's answers, removing the RF deck with the "green" gear not in place usually ends with the need to resynchronize the gearbox.
For the springs, see the attached design specifications document.
I have found some suitable substitutes, but never used those in my own R-390 and R-390As.
If ever you want to try those, let me know.

73, Jacques, VE2JFE in Montreal

Alex,
The green gear doesn't exactly "lock" the gear train.  I keeps the sections synchronized with each other when the RF deck is removed.  It is normal for it to rotate like that.
Getting the backlash set is a bit fidgety.  I found it helpful to have something that can keep the tension and the teeth of both halves matched up during the process.  If I recall correctly, I loaded them and then pushed a flat-blade screwdriver in the teeth to hold them until I could get them meshed.  i think that's necessary for both sides.  Others may have better advice for how to do that.
I don't know what might be used as replacement springs.
Thanks,
Barry - N4BUQ


On Sun, Mar 15, 2026 at 8:28 AM Alex Hopper via R-390 <r-390 at mailman.qth.net>
wrote:

> Hello All,
>
> Following my manual, I carefully removed the font panel on my 
> R-390/URR
> (non-A) last night.  I am at a point where I would like to begin the 
> process of removing the RF deck.
>
> How exactly is the green gear intended to 'operate'.  While the RF 
> deck was still in place last night, I attempted to affix the green 
> gear to it's post to the right of the KC change gear.  The green gear 
> still moved in this position when the KC change was rotated.  Does the 
> green gear work by locking the entire tuning mechanism only after the RF deck is removed?
>
> What other pitfalls should I look out for?  Reading the manual makes 
> the process of replacing the RF deck sound MUCH more difficult.  Is 
> meshing the gears back together as complex as it sounds?
>
> Finally, when the deck is out I would like to replace at least a few rather
> rusty and tired looking springs on the slug racks.   Is there a specific
> spring size/tension I should be looking for?
>
> Thanks,
> -Alex
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