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Collins 300G Tuning motors




 
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Author Topic: Collins 300G Tuning motors  (Read 2649 times)
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KD6VXI
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« Reply #25 on: November 29, 2017, 05:03:59 PM »

Two thoughts.

If their is a raised relief on one side, matching an indent on the opposite surface with the spring between them, I'd say that's for a slippage type clutch... Keeps the gears from eating themselves up.

If it's a gear with another gear that slips inside, that can be a 2 speed clutch.  If the motors hit full inertia, possibly then develop enough centrifugal force to overcome the spring pressure and change the gear ratio....  One of my old remote controlled cars had a 2 speed transmission like that.  It would hit a specific speed and shift.  You set the speed by changing the spring inside.

Or I'm out in left field.

--Shane
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KB3WFV
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« Reply #26 on: November 30, 2017, 01:10:22 AM »

..(snip).... but the motor may have a shaft that moves forward when powered, like a starter in a car..(snip)...  
Fred

Right Fred, the motor shaft moves forward when power is applied to the motor. BTW I picked up a bottle of 3 n 1 oil tonight. Sadly it's a plastic bottle, I'm gonna miss the sound the metal can made when you squeezed it to apply the oil.

Two thoughts.

If their is a raised relief on one side, matching an indent on the opposite surface with the spring between them, I'd say that's for a slippage type clutch... Keeps the gears from eating themselves up...(snip)....

--Shane
KD6VXI

Hi Shane, Thanks for the comments. Between You and Fred I think I have it figured out. Attached is a photo of the motor shaft with the pieces on it.

NOTE: THE PIECES ON THE SHAFT ARE IN THE WRONG ORDER IN THIS PHOTO

The correct order should be from RIGHT to LEFT starting at the motor body.

Pin in shaft
A washer ? (blurry picture)
A gear ? (blurry picture)
Spring
Hub
Gear
Washer
Felt washer

In the photo you can see the felt and the washer are in the wrong place (right of the hub and left of the spring). They should be left of the hub and the gear. Sorry I don't have a photo of the correct order (yet).

Understanding:
1) The correct order
2) The motor bolts to a plate (see photo of capacitor assembly with motor).
3) The tip of the motor shaft sticks through a hole in the plate
4) When the motor is installed on the plate the teeth of the left gear mesh with teeth of a gear in the gear box.

It is easy to see that the motor shaft would move to the left (in this photo) or forward as Fred mention, when power is applied. Pushing the shaft through the hole in the plate.

This would push the gear closest to the motor body to the left (in the photo) towards the plate, compressing the spring in to the hub, the left gear, the washer and felt washer which are held in place by the plate.  

This allowss the gear on the right to engage with (I think) the hub. It might engage the gear on the left instead.

When all of the componets are compressed against the motor plate wall the gear on the left turns the gear box which turns the capacitor.

When power is removed the spring pushes the shaft back towards the motor disengaging the hub or outer gear.

This is probably done to prevent gear stripping as Shane had mention or more likely to prevent overshoot or backlash from the desired capacitor setting when power is remove from the ac motor. Overshoot or backlash can occur from motor momentum or a rocking back when the voltage is removed. In other words without this clutch set up one would play a constant game of "opps, too far" and "damn, not far enough".

I have two more motors to go through, as I work on them I will try to get a better picture of the motor shaft an it's parts in the correct order.

I am pretty sure this is the correct line of thinking, any thoughts ?

Brian
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* IMG_2029.JPG (1191.72 KB, 2592x1936 - viewed 62 times.)

* IMG_2033.JPG (525.93 KB, 2592x1936 - viewed 50 times.)
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KB3WFV
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« Reply #27 on: November 30, 2017, 06:32:30 PM »

  Smiley
A working Collins 300G Grid tuning motor.

https://youtu.be/QrG0ijAryvg
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KB3WFV
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« Reply #28 on: December 02, 2017, 10:28:34 PM »


A working Grid tuning motor with capacitor assembly

https://youtu.be/Iah9gJU1wMY

Now on to the slug tuning motors....

Brian
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KA2DZT
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« Reply #29 on: December 03, 2017, 12:30:28 AM »

Great, you got the whole thing working, pretty cool the way it works.

I was thinking about how much money Collins saved by not having to put knobs on the xmtr. Grin
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KB3WFV
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« Reply #30 on: December 03, 2017, 06:56:30 PM »

.......I was thinking about how much money Collins saved by not having to put knobs on the xmtr. Grin

Yep, I had the same thought. I wonder if Coolins was setting things up for future remote transmitter site control?

Brian
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KB3WFV
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« Reply #31 on: December 03, 2017, 07:05:49 PM »

A working slug tuning motor assembly.

https://youtu.be/YRCmaTxZHRM

I was really lucky with this one. No need to disassembly anything. All that had to be done was some cleaning and some good ole 3 IN ONE oil.

Now on to number 3 and the last motor. Will my luck hold out?

Brian
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Steve - K4HX
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« Reply #32 on: December 04, 2017, 08:32:16 PM »

That's the Collins way Fred - why make is simple when you can make it complex.
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Tom W2ILA
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« Reply #33 on: December 26, 2017, 08:27:01 PM »

Good to see progress on these motors!  See the March 1954 Service Bulletin enclosed.  The setup of your IPA cap motor is the same as the two motors in the final but many of the IPA motors have survived while most PA motors are gone.
The failure mode on the PA was the internal surface of the ceramic coils were coated with cigarette smoke, dreck and mung.  The tuning motors attempted to push the piston through the ceramic coil but eventually bound and stuck in the mung.  The engineer could hear the motor spinning and plate current was not changing so the motor was kept spinning. The flexible metal push tape got wrapped around the axle and broke (first safety) , then the drive shaft reached its mechanical stop.  At that point the slip clutch (second safety) should have started spinning.  But, the slip clutch no longer slipped because it too was now glued together with cigarette tar, dreck and mung.  So the next and final sacrificial part was the fiber gear.  And that was the death of many a drive motor gear train.

Squeeky clean the gear train and clean/lube the slip clutch (it is the larger aluminum cylinder attached to the large, very fine tooth gear).  The slip clutch should give way relatively easily using hand pressure on the gears.  Clean & polish the inner surfaces of the coils and the aluminum pistons so the pistons slide smoothly without binding.  But be careful removing those coils so as not to let them unwind like I did unless you plan to rewind the coils that scorched.  From what I remember when seeing your transmitter in Florida it was much cleaner than many but still has some accumulation of 60 year old dust/dirt/old grease to flush.

Todd and I have talked about printing new gears so if someone has access to a print solution a few are needed.  There is a bronze gear centered on the fiber gear so that bronze core could be epoxied to the printed gear.  At one point I was in touch with Boston gear but never pushed to finding if they had a replacement.

I have a vague plan to replace the motors with small 24vdc gear motors that will tap into the original gear train.  

73
Tom  


* 300g gear.jpg (305.57 KB, 1306x1526 - viewed 32 times.)

* 300g motor svc bulletin .jpg (711.9 KB, 1464x1888 - viewed 33 times.)
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KU8L
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« Reply #34 on: December 27, 2017, 12:24:41 PM »

A good Clock builder will be able to fabricate pretty much any gear that you would need.  They do it all the time.  Brass would be the preferred material. 

FWIW

Curt
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