[R-390] need help with intermittent gear aka Geneva gear

Sun Jan 12 17:59:08 EST 2014

Phil,

Knowing when and where you need the  intermittent gear aka Geneva gear
to move is half the problem. Once you understand when it needs to move
and to what band position it needs to move to , Getting it aligned is easy.

There were some other post pointing to some other tings to also look for.
If you are not finding the proper intermittent movement you may need to follow up on
those points. If the intermittent movement is just at the wrong place as you dial through the 
Mega Hertz then that's an easy adjustment. 

Ten turns on the Mega Hertz shaft gets you from end to end on the counter dial.
It drives a set of cams through their travel range.
It drive the intermittent gear aka Geneva gear through it range.
Setting and timing the intermittent gear aka Geneva gear is like setting a cam shaft alignment.
But you do not get a timing mark. You do have to watch the operation of the RF band switch.
You want that switch to move as you change the Mega Hertz shaft between mega hertz.
You want the RF band switch to complete its operation as the Mega Hertz shaft drops into a detent position.
You want the RF band switch to complete its operation while tuning up or down one Mega Hertz and at the proper change points.

Roger 

Roger,  thanks for the reply.

Your info on getting the mega heartz detent set so that
it is between bandswitch changes is something that I
did not know about.  I will have to think about how to
accomplish that as the planetary gear is the last thing
I put in place before putting the front plate on.  At this
point, I'm not even sure I'm getting the Geneva gear to
go through six changes but I will look into that.

As for aligning the bandswitch itself, that is no problem
for me as I've done it before and it is clearly illustrated
in the gear rebuild tutorial in the Y2K manual.

thanks again, Phil

----- Original Message ----- 

From:   Roger Ruszkowski 

To: pmills7 at comcast.net 

Sent: Sunday, January 12, 2014 2:06   PM

Subject: Re: [R-390] need help with   intermittent gear aka Geneva gear

Phil,

Pull the RF deck one more time and do not put it back in until you get it   aligned.

Stage one of two.

You want to see the intermittent gear move the band switch as the Mega   Hertz shaft is rotated.

Going up the range you need a shift from .5 to 1, 1 to 2, 3 to 4, 7 to 8,   15 to 16.

Five shifts for six octaves. 

Going down the range you need a shift from 16 to 15, 8 to 7 , 4 to 3, 2   to 1, 1 to .5

This will be right or wrong. 

Start in the mid range to avoid the bottom end stop on .5

As you change the Mega Hertz shaft and move the dial counter between 7   and 8 you need the band switch

to shift positions.

You need a nice clean start, shift and rest of the switch as the shaft   goes from detent stop to detent stop.

The R390A TM and the Y2K manual show the same gear train drawing and part   numbers.

Looking in from the bottom of the RF gear train right behind the dial   counter is a short shaft.

>From front to back is a small gear a big gear (66) a clamp (71) and   small gear (79).

If the switch is not moving at the right time and centered in motion   between the Mega Hertz detent stops.

If the motion is not quite centered going both up and down at all the   switch points, turn the Mega Hertz shaft

 until the intermittent gear completes its motion. Then loosen   the clamp (71) on the small gear. Dial the Mega Hertz shaft

over to where it needs to be in a detent stop and tighten the clamp.

You may need several shots at this to get the operation smooth and well   centered at all five of the switch

 points going both up and down the range of the gear train.

This adjustment is just to get the  intermittent gear switching   at the correct points.

Stage two of two.

Adjusting the band switch position.

The band switch has 8 wafers with 6 positions each this is 48 contacts   that must make well.

There is a spot between the band switch gear and the band   switch shaft where all is well.

This is an eye ball value. Do it by sight and not with a meter like   it says in the TM.

Each wafer and contact will be a bit different and not exactly   center.

Run the gear train from end to end both up and down. Watch the switch   settings as the  intermittent Geneva gear 

settles after a shift. You may need to loosen the switch shaft gear clamp   and nudge the shaft a bit one way or another to better

ensure each switch wafer contact makes at all the points. You will eye   ball 48 contacts coming and going and then try for a best fit where 

every thing works when needed. 

Once you get the Geneva gear moving at the right octave change points and   the band switch shaft timed for good switch contacts on

each wafer point your good on this part of the alignment.

Phil, Just because I think this reads well does not mean that it   does.

If you have questions please put up another post.

Roger AI4NI

I just can't seem to get this one right....I've got all the rest of
the gear train set up and aligned but I can't seem to get the
intermittent gear on the bandswitch to work correctly and the
drawing in the manual is not much help.  I know that some of
the teeth on the little gear between the intermittent gear and
the bandswitch gear are longer than others and I suspect that
these are not in sync with whatever on the intermittent gear.
I have been told that these longer teeth are supposed to run
up/down with the bandswitch in the 7 mc position but I've
tried this in conjunction with what I think is the correct setup
for the intermittent gear according to the manual drawing.

I've been working with this so much that I can go from complete
rf deck on the bench down to the intermittent gear and back 
fully reassembled in less that 15 minutes which shows
that I've had a lot of practice :-)

Can anyone offer any help or instructions on how to get these
gears positioned so they work correctly?

thanks, Phil   W5BVB

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