[R-390] More geartrain rebuild info

[Bob Camp]

Hi

Purely as a controlled experiment I have *also* done the gear shuffle. 
They do go back together fairly well when you randomize them.

The real trick is to put it all together and then rotate it. It should 
spin freely with no binding. If you have a point that it binds at then 
there is a gear mismatch or bur somewhere.

On page 3-23 of the Y2K manual there is an interesting block diagram of 
the RF deck gear train. The gizmo we call the planetary gear is called 
out as a differential in the drawing. On page 3-26 section 4 goes into 
all the messy details of the beast. Bottom line - yes it is driven by 
both the KC and MC knobs to allow you to tune to both the correct KHz 
and MHz.

My main concern with the planetary is that it is very much driven off 
of the KC knob. Because of that any drag is noticeable as you tune in a 
signal. If you want one of these radios that will tune from one end of 
a sub band to the other with a single twist of the KC knob then the 
planetary needs to be in pretty darn good shape.

	Take Care!

		Bob Camp
		KB8TQ



On Feb 24, 2005, at 11:17 PM, Barry wrote:

> Well, I suppose I'm outta luck on this one.  I've played musical gears 
> with
> them already so there's no way for me to tell which one's mate is 
> which.  I
> just hope any effect will be minimal.
>
> Also, does the planetary gear revolve on KC changes or is it only on 
> MC?  I
> can't see the geartrain on my other radio to tell.
>
> Barry(III) - N4BUQ
>
>
>> Hi
>>
>> I very much agree that a gear train with a reasonable amount of crud 
>> in
>> it probably will require the planetary gears be torn down. When you do
>> the only way to really get them clean is to take them down to pieces
>> and clean each one.
>>
>> The obvious gotcha is how do I get these back together with only two
>> hands and a limited number of toes involved. Cleverly bent paper clips
>> seem to be the "other" way to do this if you don't have access to 
>> stuff
>> like plastic hemostats.
>>
>> Here's an issue that's a little more subtle. The gears probably left
>> the factory all nice and uniform. When they did you could swap any
>> "top" with any "bottom" and there would be no net effect at all. Over
>> the years each "top" has rubbed against it's respective "bottom" for a
>> really long time. Essentially you have created matched pairs of gear
>> halves.
>>
>> So in addition to needing a number of fingers and toes to put it all
>> back together you also need three sets of eyes to make sure all the
>> sets remain with each other.
>>
>> The gear will work pretty darn well even if you randomize the gears. 
>> My
>> story is that it was a controlled experiment and I'm sticking to it. 
>> If
>> you want a silky smooth gear set when you are done it seems to be best
>> to keep everything in order ....
>>
>>     Enjoy!
>>
>>         Bob Camp
>>         KB8TQ
>>
>>
>>
>> On Feb 23, 2005, at 10:19 PM, Barry wrote:
>>
>>> List,
>>>
>>> In the process of tearing down this geartrain, I noticed the 
>>> planetary
>>> gears
>>> were quite clogged with grease.  Scott's slide show says it probably
>>> isn't
>>> necessary to tear the planetary gears apart, but it didn't appear I
>>> would
>>> get this one clean unless I did and I'm sure glad I did.
>>>
>>> Upon taking apart the three split gears, all three exhibited a fair
>>> amount
>>> of drag when I twisted them against each other.  Upon closer
>>> inspection, I
>>> could see small burrs on the teeth.  After removing these burrs, the
>>> gears
>>> ride smoothly against each other.  I would never have known this
>>> unless I
>>> disassembled them.  Also, it gives me a good chance to ensure a lot 
>>> of
>>> the
>>> hardened grease and dirt is removed.  After a 24-hour soaking in
>>> kerosene,
>>> there was still a significant amount of grime in this assembly.
>>>
>>> Now if I can figure out how to get four split gears all tensioned and
>>> reassembled at the same time!
>>>
>>> Barry(III) - N4BUQ
>>>
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>>
>>
>
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