[R-390] Gear Train Removal

Thu Sep 5 10:32:48 EDT 2024

Hi Barry,
Good news !
Let us know how the alignment goes.

73, Jacques, VE2JFE in Montreal

-----Message d'origine-----
De : r-390-bounces at mailman.qth.net <r-390-bounces at mailman.qth.net> De la part de Barry Scott
Envoyé : 4 septembre 2024 19:15
À : Jim Whartenby <old_radio at aol.com>
Cc : R-390 Mailing List <r-390 at mailman.qth.net>
Objet : Re: [R-390] Gear Train Removal

Success!

TM 11-5820-357-35 (1962), at the top of page 84 (Step (50) (a) states that
S206 should be on contact 5 for MC=2 (contact 7 for MC=0 and contact 6 for MC=1).  Once I had that in position, then rotating the KC gear eventually brought all the cams into alignment.  Whew!

Thanks,
Barry - N4BUQ

On Wed, Sep 4, 2024 at 1:19 PM Jim Whartenby via R-390 < r-390 at mailman.qth.net> wrote:

> Barry
> What you have experienced was a know shortcoming of the original R-390 
> design and is mentioned in "Chapter 6.0 Recommendations" starting on 
> page
> 79 of the Final Engineering Report.  Also mentioned are mechanical 
> filters and tubes used that could have been upgraded if better tubes 
> were available earlier in the design.  But at some point, the design 
> work had to stop or it would have never left the engineering phase.  
> There is a point reached where the design is "Good Enough" aka GE.
> Relax and take a breath, nothing you have done is fatal and all can be 
> corrected.  Keep us informed.
> JimLogic: Method used to arrive at the wrong conclusion, with confidence.
> Murphy
>
>     On Wednesday, September 4, 2024 at 12:43:14 PM CDT, Jacques Fortin 
> < jacques.f at videotron.ca> wrote:
>
>  Ah, also forgot to mention: the RF deck have to be re-installed in 
> the frame (see procedure chapter 59) BEFORE any re-alignment is 
> attempted !
>
> 73, Jacques, VE2JFE in Montreal
>
> Barry, some COMMENTS imbedded in your text below.
>
> 73, Jacques, VE2JFE in Montreal
>
> Well, I don't quite know how it happened, but I can no longer get all 
> the cams properly aligned.  As I mentioned, I've removed the VR 
> counter so that's one point of reference that I no longer have.
>
> AH, DON'T WORRY: I HAVE DONE THE SAME FEW YEARS AGO....
>
> I had been rotating the MC change gear one click or two and then back 
> and no problem; however, I think I lost track of which way I had 
> rotated it and now I can't get back to where 2.000 would normally be 
> displayed by the counter.
>
> FOR THE MC POSITION, JUST RELY ON THE ROTATING DIAL OF THE SYNC XTAL 
> OSC THAT INDICATE ON WHICH MC POSITION THE SWITCHES ARE.
>
> I'll mention that I've kept the Green Gear in place and, contrary to 
> my previous comment, that gear does indeed keep the MC and KC gears 
> synchronized and, given that, I don't know how they're no longer where 
> I can get them back in sync.
>
> IT DEPEND ALSO IF YOU SET THE PROPER MECHANISM POSITION CORRECTLY 
> BEFORE REMOVING THE RF DECK.
> READ THE CHAPTER 59 CAREFULLY AGAIN !!!
> THEN, ROTATE THE KC SHAFT AND TRY FIRST TO ALIGN THE 8-16 MC CAM.
> IF YOU ARE LUCKY, ALL THE OTHER ONES WILL ALIGN (IF THEY WERE ALIGNED 
> CORRECTLY PREVIOUSLY).
> IF NOT, TRY A FULL TURN AROUND LEFT OR RIGHT (DEPENDING THAT YOU 
> REMEMBER OR NOT WHAT YOU HAVE DONE BEFORE).
> OR... JUST TAKE THE PROPER ALIGNMENT OF THE 8-16 mc AS THE STARTING 
> POINT AND FOLLOW THE FULL CAMS RE-ALIGNMENT PROCEDURE CAREFULLY !
>
> According to the manual, as part of the complete gear teardown and 
> rebuild (which I still have not decided to do), one is supposed to be 
> able to rotate the MC gear CW (which I presume is taken to mean "CW as 
> viewed from the rear"), until it hits a stop point and then, back up 
> to the nearest notch which should correspond to 0.000.  My presumption 
> is that if I back off to the 3rd click, that should correspond to 
> 2.XXX and rotating the KC shaft should eventually get the gears (and 
> cams) in the 2.000 position.
>
> I found that there is something that causes a "stop" at full CW and 
> full CCW.  I think that stop is happening as a function of the Geneva 
> mechanism and not the 10-turn stops (which aren't engaged when the RF 
> deck is removed); however, CW or CCW still won't let me get the 
> gears/cams in their proper setting and am wondering if I'm now truly "stuck".
>
> Any help is appreciated.
>
> Additionally, to avoid getting the transformers' cores wet, I'm 
> removing the slug racks and transformers while cleaning the gears and, 
> right off, I found that one of the slugs (for Z2223) was broken.  I'm 
> sure that didn't help performance any.  I have it CA glued back 
> together so that should help when I get this all reassembled.
>
> Thanks again,
> Barry - N4BUQ
>
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