[R-390] my PTO problem, part II

Fri Jul 12 07:33:20 EDT 2013

Hi Roger,

Thank you for the email, advice and all information.

I am scared about messing with the corrector stack. I hope it is solidly
held in place so I cant accidentally mess it.

I will take pictures and make video on the way.

Thanks,

Felipe

Felipe Ceglia - PY1NB
-------------------------------------------------------------------------------------
PR1T team member /// Rio DX Group member /// Araucaria DX Group member
http://dxwatch.com /// http://reversebeacon.net /// http://riodxgroup.com

On Thu, Jul 11, 2013 at 11:50 PM, Roger Ruszkowski <
flowertime01 at wmconnect.com> wrote:

>
>
> Felipe,
>
> I think you just got a good sample of very good advice.
>
> Tisha's  idea that you could be ahead to just buy another PTO
> is in line.
>
> I watched your two videos. (nice job).
>
> You are moving the shaft and the guts have a back lash inside.
>
> We all know this Is not good. PTO's do not have internal backlash.
> That is part of what makes PTO so wonderful. OK a couple hertz back lash
> but not like your video.
>
> As posted by the other Fellows do not let those cans scare you.
>
> Do not disassemble the corrector stack.
> Find some other method to make your self feel bad before you
> unbolt a corrector stack inside a PTO.
>
> Ok with all the mental health warnings out of the way we can proceed.
>
> Do some more video as you go. The next stage in R390 archiving.
>
> We do not have photos of VFO guts in color or moving video.
> We have not been in there since the camera was invented
> We would all like to see what ever  video you can get up on the web.
>
> And we thank you in advance for taking the time.
> You are about to become famous if you take on this mission.
> No money and little fame but we know who you are and will always thank you.
>
> You will have to unsolder some heater wires as you go.
> Not a big deal its just part of the disassemble process.
>
> Inside, the shaft is just a nice acme thread on the shaft.
> on the shaft is a carrier  with a matching set of threads in it.
>
> Turning the shaft moves the carrier along the axis of the can.
> The carrier slides a slug through a core not unlike watching a slug move
> in one of the RF deck's tuning coils with cores.
>
> The PTO slug is a bit larger than the RF deck slugs.
>
> The corrector stack acts as the device that keeps the carrier from going
> round and round as the
> shaft is turned and thus forces the carrier to move along the threaded
> shaft.
>
> I am thinking gummed up thread on the carrier mechanism.
> The runner on the carrier must follow the stack and not back lash.
>
> Yours does. The carrier runs one side against the stack. The
> back side is spring loaded against another rail.
>
> As you change direction the shaft to carrier threads are so gummed up,
> that instead of the spring having enough strength to hold the carrier
> against
> the stack, the spring gets compressed, the carrier torques over to the
> other rail
> (back lash) before it meets enough resistance that the threads begin to
> move.
>
> The shaft bushing is also gummed up or when you dialed the PTO back and
> let go,
> the spring would push the carrier back against the stack and you would get
> a counter lash effect.
>
> I think you just need some cleaning inside the PTO to restore the VFO to
> good operation.
>
> The stack we describe is like an S Curve. as it is not straight, over the
> tuning range.
> It lets the threads get a little ahead or behind the curve to provide a
> more linear operation.
>
> Once you get the PTO open you will see the coil has a magic non linear
> wind.
> The coils got wound on the form by machine (lath).
> A simple pattern lath. The pattern was hand make and tweaked to get it
> as linier with the PTO slug as possible. Real black magic in the
> manufacturing process.
>
> It was tired and retried to get it almost perfect.
>
> Then the stack was adjusted by hand during assembly for awesome good
> behavior.
>
> The secret to getting the stack together in manufacturing was the exact
> red color of the stick em.
> Not true it was air dry time of the stick em.
> The stuff was sticky enough to hold the mess in place but not so loose it
> would let things slide
> out of adjustment. Not so stiff to make adjustment hard. Not to fast
> drying to prevent you from
> getting the adjustment done.
>
> Things were painted up and bolted loosely together.
> Then the unit was let set on the line until it was about the right dry
> state.
> Then you selected the unit when it had "cured" just right and popped it
> into the jig.
> Hooked it up and with a gauge block S curve in one hand and a stick in the
> other hand
> you sweep the corrector stack into perfect adjustment as you dialed the
> PTO through 11 turns or
> so from stop to stop. And then tighten every thing up and run one more
> pass for a check.
>
> It took longer to type this than it took to do it on the production line.
>
> Not having the magic red stuff in hand with S curve guide, do not loosen
> the
> corrector stack and thus cause it to come un adjusted.
>
> Some brave souls  have been down this path.
> You can read about them in the same history book you are about
> to be recorded in if you do some video.
> These wonderful  Fellows tell us that when they were done
> the linearity of the PTO under maintenance was no better than
> when they started. The women at Collins aligned them as good as could be
> done.
> And Fellows should not try and out do the women.
>
> Thus we tell you do not undo the corrector stack.
>
> But have fun with the rest of it.
>
> You can likely save in an afternoon.
>
> And be happy that you did.
> You will likely spend more time doing video for every one
> than it takes to clean the PTO up.
> Take the time and point out all the parts and what you find
> / found as you go.
>
> Honest this is an effort that needs to be done.
>
> Good luck with fixing the PTO and doing a video.
>
> I hope there is enough info here to guide you through
> the process,
>
> I do not hang on my mail like I should.
> but I will get back to you if you need more help.
>
> If you have problems do some more post.
> The Fellows will jump in and get you some timely responses.
>
> If you are looking for some history or good words to put with the
> video just ask the Fellows here. You can see from the
> mail there is plenty of experience to help you along.
>
> Roger an old  33C4H
>
>
>
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