[R-390] R390/URR Gear train

Francesco Ledda frledda at att.net
Sun Jun 9 20:07:30 EDT 2019 

Very nice job!

Sent from my iPad

> On Jun 9, 2019, at 18:41, <jgedde at optonline.net> <jgedde at optonline.net> wrote:
> 
> Thanks Don!
> 
> Oh yes, I am indeed familiar!  Too much so.  When I set the MC gear I ran it fully counterclockwise and installed the deck with the MC band set slightly below zero, but not as far as where it stopped.  So, when it's been installed I hit the 10-turn stop before I hit the end of travel for the deck itself.
> 
> That RF deck geartrain is definitely not for the faint of heart.  I took the deck off to fix a crackle I get on the 0 MHz band.  Thinking it was the switch, I went in there with intent to clean the switch up.  Being able to see the gears up close, I decided all that gunk HAD to go and that started the ordeal.  All pieces apart and cleaned in an ultrasonic cleaner with Purple Power/water and the gunk all came off although it took several runs to get it all off.  Changed out the water/purple power three times because it got so dirty I couldn't see the parts anymore!  The KC dial has a nice feel now.  Before it was very loose and sloppy feeling and bound up every now and then.  Now it has a slightly snug (damped feeling), slop free feel, yet turns easily enough that I can spin the dial with one finger.
> 
> Interestingly, whatever it the crap was, mineral spirits didn't touch it (no I didn’t put MS in the ultrasonic cleaner 😊  ).
> 
> The gears are now lubed with Mobil Vacuoline machine tool way and gear oil from my home machine shop which is basically a detergent free medium weight oil with a tackifier additive so it stays put.  It's made to be such that it stays where you put it, but doesn't make a mess, doesn't attract dirt more than any oil, doesn't have an offensive odor, and works with a very thin film.  The gears, shafts, bushings, etc. are well lubricated but you're hard-pressed to look at them and tell there's oil on them.  Just the way I think it ought to be.   The tackifier additive Mobil puts in there makes the oil kind of like you see in those auto parts store demos with the crank and gears where it makes the oil stick to the gears.  (but for goodness sakes, don't put that Lucas snake oil, junk in your car's engine oil!!!  I have a some tribology background and climbing oil is NOT what you want to happen inside your engine.  But I digress...)
> 
> While I was in there, I cleaned the Veeder-Root in the ultrasonic cleaner with a well diluted mix of water and purple power, then repainted the shield/fingers over the numbers with thinned satin black acrylic enamel.  Looks like new!
> 
> A pic of the RF geartrain back together is attached.
> 
> John
> 
> -----Original Message-----
> From: Don Heywood <wc4g at knology.net> 
> Sent: Sunday, June 9, 2019 6:18 PM
> To: jgedde at optonline.net
> Subject: Re: [R-390] R390/URR Gear train
> 
> Congratulations John, that RF deck is no easy task. There is one thing I have discovered you may be interested in, I will try to explain:
> 
> When you turn the MC knob down to zero you will notice that it goes just a little farther 'below zero'. This is where the ten turn stop should be set. 
> Any further rotation should be stopped by the ten turn stop on the MC shaft. 
> If this is not properly set the force will be applied to the Geneva Mechanism, no Buenos... By now you should be familiar with what I am saying.
> 
> Good Luck and I was glad to help.      73 Don, WC4G
> 
> 
> -----Original Message-----
> From: jgedde at optonline.net
> Sent: Sunday, June 09, 2019 5:35 PM
> To: 'Don Heywood'
> Subject: RE: [R-390] R390/URR Gear train
> 
> It's all back together and everything is preloaded properly.  The KC dial takes a slight bit more effort to turn, but there's no slop whatsoever (it feels like my R390A).  The gunk is all cleaned off the gears, the rf deck has been reinstalled and the radio aligned.  It didn't really need that much adjustment which means to me I put the geartrain back together correctly.
> What an ordeal though.  I won't do that again any time soon...
> 
> John
> 
> -----Original Message-----
> From: Don Heywood <wc4g at knology.net>
> Sent: Saturday, June 8, 2019 5:28 PM
> To: jgedde at optonline.net
> Subject: Re: [R-390] R390/URR Gear train
> 
> OK, John, I turned one of my receivers up on end and can see that those gears with the four holes will mesh with the small gear on the PTO shaft when you reinstall the RF deck and mate it with the KC knob mechanism. I took a picture and attached it.
> 
> -----Original Message-----
> From: jgedde at optonline.net
> Sent: Saturday, June 08, 2019 4:12 PM
> To: 'Don Heywood'
> Subject: RE: [R-390] R390/URR Gear train
> 
> Hiya Don,
> 
> I get the preload thing there are about a half dozen other ones I already did in putting it back together.  This one is different as it doesn't seem to be able to lock itself.  What I mean is this...  All of the other split gears get preloaded then the preloaded gear engages itself in another gear - a single one so as to be able to spring open within the gear profile of the regular gear and eliminate backlash...  The key thing with this is that the split gear spreads between teeth on a single gear.  Easy.
> 
> Now, the one I'm asking about preloads but engages in to*two* separate
> gears.  One preload gear for each of the two normal gears.   In other words,
> the preloaded gear engages to another split gear except that gear doesn't have springs nor is the split laying on top of each other.  There's a spacer between the two gears.  It's very strange.  If you look at the bottom of my picture you'll see a steel gear with four big holes in it.  Directly behind that gear is another just like it.  There's a spacer between them.  One of those two gears is connected to the shaft and the other can freely rotate on the shaft.  Above that gear to the left is the split gear.  It's much bigger than all of the other split gears and is made of brass.  It has no holes in it apart from where the springs are located.  See it?  That gear can be preloaded but each of the sprung pair engages to a separate gear and the preload just unwinds!  That's what's throwing me.
> 
> John
> 
> -----Original Message-----
> From: Don Heywood <wc4g at knology.net>
> Sent: Saturday, June 8, 2019 2:59 PM
> To: jgedde at optonline.net
> Subject: Re: [R-390] R390/URR Gear train
> 
> John, I know the section of Pearls I referred you to is for the "A" model but the preload information still applies, in fact a lot of the pearls also affect the older model we work on. There has been a section added just for this older radio the R-390/URR!
> I can't see any number 79 in your picture, but if the gears have a set of springs between them then they need to be preloaded.
> This preloading procedure takes practice, slide one gear carefully to disengage from the gear it meshes with leaving its mate engaged, then using your thumb and forefinger slide the gears to overlap a tooth or two and while holding this relationship slide the first gear back onto the mating gear. If the springs come loose reinsert them with fine needle nose pliers of forceps.
> 
> I am only trying to help. I had to learn all this the hard way.
> 
> Don
> 
> 
> -----Original Message-----
> From: jgedde at optonline.net
> Sent: Saturday, June 08, 2019 2:30 PM
> To: 'Don Heywood'
> Subject: RE: [R-390] R390/URR Gear train
> 
> Hi Don and thanks,
> 
> You pointed me to the R390A pearls and I'm working on a R390.  The R390A from what I can see, doesn't even have the gear I'm talking about.  There are a bunch of preloaded gears, but it's the one in particular I'm referring to.  It doesn't seem to have any way of holding preload.  Is it some kind of sprung thingamabob to prevent excess force on some part of the mechanism?  I understand the purpose of the split gears to eliminate backlash, but this gear has nothing to lock to since the gears it meshes with are both freely rotatable.  It's hard to explain.  In my photo, the two spaced gears on the part marked 79 can both rotate independently.  It wasn't preloaded to start with either yet everything seemed to work...
> 
> John
> 
> -----Original Message-----
> From: Don Heywood <wc4g at knology.net>
> Sent: Saturday, June 8, 2019 2:07 PM
> To: jgedde at optonline.net
> Subject: Re: [R-390] R390/URR Gear train
> 
> Hi John, please go to: <http://www.r-390a.net/Pearls/> and look under the RF deck mechanical section and then do a work search (cont. f) for "preload"
> and see all the data. This preloading is to keep tension on the teeth to preclude any backlash when tuning back and forth, hence - no slop - have fun , 73, Don WC4G
> 
> -----Original Message-----
> From: jgedde at optonline.net
> Sent: Saturday, June 08, 2019 1:39 PM
> To: r-390 at mailman.qth.net
> Subject: [R-390] R390/URR Gear train
> 
> I took apart my geartrain for cleaning this morning on the 390.  No end to solidified lubricant.  Now I'm putting it back together.  I noticed before I took it apart that the big brass split gear (part 73) wasn't preloaded.
> Nowhere in the manual does it say how this should be done or what it's supposed to preload.  What is this for?  It meshes with another gear assembly (79) that has two gears separated by a spacer.
> 
> 
> 
> I've attached a photo of what I'm asking about.
> 
> 
> 
> John
> 
> 
> 
> 
> 
> 
> 
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> <clean gears.jpg>
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