[R-390] need help with intermittent gear aka Geneva gear
Barry
n4buq at knology.net
Mon Jan 13 10:17:26 EST 2014
Is is possible the Geneva mechanism just isn't clocking the way it should? I seem to recall that when I rebuilt one I used to have, someone made the comment that if that ball/track isn't just exactly the right size, the mechanism just wouldn't clock.
Thanks,
Barry - N4BUQ
----- Original Message -----
> From: "Roger Ruszkowski" <flowertime01 at wmconnect.com>
> To: r-390 at mailman.qth.net
> Sent: Sunday, January 12, 2014 4:59:08 PM
> Subject: Re: [R-390] need help with intermittent gear aka Geneva gear
>
>
> 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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