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Author Topic: Sources for insulated shaft couplers  (Read 3160 times)
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wx3k
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« on: February 20, 2010, 03:07:38 PM »

I want to replace the shaft coupler on my Ranger VFO. During my careful disassembly of the ranger to replace R3 with a higher power value, I noticed that the phenolic on the coupler was cracked. (no wise cracks about how I wasnt  careful in disassembly of the ranger)  Undecided

The present one is usable but rather than have to rip the rig apart again, I want to see if I can find a replacement.

Shaft is 1/4", coupler is insulated and 1 inch wide and about 3/4" deep. Any ideas ?

I was thinking it might be possible to rebuild the one I have by substituting a flexible, insulating material and use small hardware to reassemble it. Has anyone tried this ?
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Stephanie WX3K
Eico 720/722/730  HRO50T
"Thunder is good; Thunder is impressive but it is lightning that does the work" ...Mark Twain
AB2EZ
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« Reply #1 on: February 20, 2010, 03:23:42 PM »

Stephanie

I repaired a broken Ranger VFO coupler for Ray... KC2PTS... using the following technique (although... if someone has a real replacement, that would be better)

If I recall, the shaft diameter of the variable capacitor is different from the shaft diameter of the tuning mechanism.

 started with a nylon spacer:  1/2" outer diameter with a 1/8" inner diameter bore, and about 1" long (my True Value hardware store used to carry these nylon spacers). I drilled it from both ends to match the two different shaft diameters. Then I drilled and tapped holes for set screws.

It was a little tricky... but it worked. To my knowledge, that Ranger is still working fine with this new coupler.
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Stewart ("Stu") Personick
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WQ9E
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« Reply #2 on: February 20, 2010, 03:27:37 PM »

Stephanie,

Many years ago I learned the hard way, with a Valiant, to loosen that coupler before flipping the heavy Valiant upside down.  I repaired that one using a piece of phenolic sheet and tiny hardware and over 10 years later it is still fine.

On the Valiant, the input and output shaft sizes for the coupler are different and I thought the Ranger was the same?  In any case, I think you are better off repairing than trying to find a replacement that isn't already damaged.

While you are doing this, does the VFO tuning feel a bit rough?  Every older Johnson rig I have gone through with the built in VFO has had badly dried and dirty grease in the ball reduction tuning and cleaning along with new lube greatly improves the tuning feel.  You need to take the front escutcheon off and then the reduction unit is easy to remove.   Once out, you unscrew the two parts of the reduction case (be careful not to let the little ball bearings get away although they are a standard size and easy to replace) to disassemble and I use WD-40 to clean the old grease and dirt.  After drying, use a general purpose lubricant to repack the mechanism and tighten the two sides together enough that the reduction drive doesn't slip.  Too loose and it slips while too tight results in requiring too much turning force.  

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Rodger WQ9E
wx3k
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« Reply #3 on: February 20, 2010, 03:49:22 PM »

That is quite an ambitious fix Stu Wink

Stephanie

I repaired a broken Ranger VFO coupler for Ray... KC2PTS... using the following technique (although... if someone has a real replacement, that would be better)

If I recall, the shaft diameter of the variable capacitor is different from the shaft diameter of the tuning mechanism.

 started with a nylon spacer:  1/2" outer diameter with a 1/8" inner diameter bore, and about 1" long (my True Value hardware store used to carry these nylon spacers). I drilled it from both ends to match the two different shaft diameters. Then I drilled and tapped holes for set screws.

It was a little tricky... but it worked. To my knowledge, that Ranger is still working fine with this new coupler.
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Stephanie WX3K
Eico 720/722/730  HRO50T
"Thunder is good; Thunder is impressive but it is lightning that does the work" ...Mark Twain
wx3k
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« Reply #4 on: February 20, 2010, 03:52:45 PM »

I had no idea about the phenolic coupler until I loosened the gear reduction nut and removed the front panel. It may have been previously cracked but in any event, where does one find phenolic sheeting ?

Yes ! The tuning is rough and I did notice this when I started to fiddle around with the gear reduction drive. I will make an effort to dissemble that and lose all the ball bearings in the process  Roll Eyes

Stephanie,

Many years ago I learned the hard way, with a Valiant, to loosen that coupler before flipping the heavy Valiant upside down.  I repaired that one using a piece of phenolic sheet and tiny hardware and over 10 years later it is still fine.

On the Valiant, the input and output shaft sizes for the coupler are different and I thought the Ranger was the same?  In any case, I think you are better off repairing than trying to find a replacement that isn't already damaged.

While you are doing this, does the VFO tuning feel a bit rough?  Every older Johnson rig I have gone through with the built in VFO has had badly dried and dirty grease in the ball reduction tuning and cleaning along with new lube greatly improves the tuning feel.  You need to take the front escutcheon off and then the reduction unit is easy to remove.   Once out, you unscrew the two parts of the reduction case (be careful not to let the little ball bearings get away although they are a standard size and easy to replace) to disassemble and I use WD-40 to clean the old grease and dirt.  After drying, use a general purpose lubricant to repack the mechanism and tighten the two sides together enough that the reduction drive doesn't slip.  Too loose and it slips while too tight results in requiring too much turning force.  


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Stephanie WX3K
Eico 720/722/730  HRO50T
"Thunder is good; Thunder is impressive but it is lightning that does the work" ...Mark Twain
WQ9E
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« Reply #5 on: February 20, 2010, 04:06:19 PM »

I had no idea about the phenolic coupler until I loosened the gear reduction nut and removed the front panel. It may have been previously cracked but in any event, where does one find phenolic sheeting ?


I found a little piece in my junk box but any stiff plastic should work just fine.  Try one of the home products stores like Lowes or Home Depot and I think one of the blue plastic covers for electrical junction boxes might yield a suitable material if it isn't overly thick.  I recall reading somewhere that someone used an old laminated drivers license as the repair material so if you don't find what you need just do a quick pick pocket routine so you don't have to destroy your own license Smiley

The little balls tend to stick in the old grease so they probably will not be a problem.  I have come across two different styles.  One has a loose end bearing used as the shaft thrust bearing while the other style has the end bearing formed as part of the shaft.
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Rodger WQ9E
wx3k
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« Reply #6 on: February 20, 2010, 04:27:17 PM »

Ah ! The plastic from an old credit card might make a good substitute !  Smiley

I had no idea about the phenolic coupler until I loosened the gear reduction nut and removed the front panel. It may have been previously cracked but in any event, where does one find phenolic sheeting ?


I found a little piece in my junk box but any stiff plastic should work just fine.  Try one of the home products stores like Lowes or Home Depot and I think one of the blue plastic covers for electrical junction boxes might yield a suitable material if it isn't overly thick.  I recall reading somewhere that someone used an old laminated drivers license as the repair material so if you don't find what you need just do a quick pick pocket routine so you don't have to destroy your own license Smiley

The little balls tend to stick in the old grease so they probably will not be a problem.  I have come across two different styles.  One has a loose end bearing used as the shaft thrust bearing while the other style has the end bearing formed as part of the shaft.
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Stephanie WX3K
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« Reply #7 on: February 20, 2010, 04:33:21 PM »

Maybee some AOL CD's ..... they showed up like cred it card applications in the US Mail.... ..

klc
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k4kyv
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Don
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« Reply #8 on: February 20, 2010, 06:47:19 PM »

If the phenolic disc is just cracked, repair it with epoxy, and it should last for years.  Then keep an eye out for a replacement and keep it on the shelf in case you ever need it.

I repaired a broken piece of phenolic in one of my overload relays about 10 years ago and it's still working fine.
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Don, K4KYV                                       AMI#5
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WA1GFZ
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« Reply #9 on: February 20, 2010, 07:48:55 PM »

How about G10 PC board material. Check Fair Radio maybe they have small couplers.
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WBear2GCR
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« Reply #10 on: February 20, 2010, 07:53:43 PM »

The credit card material ought to work, but it is not happy with high temps - it will likely become brittle or soft and crack in time.

A better choice is a bit of PC board material - lots of phenolic available by grabbing any consumer gear off the street, especially old computer monitors (you can grab the rest of the parts off the board too...) or better still is some fiberglass PCB material, the green stuff. You can etch off the remaining copper...

Another way to go is to use some flexible tubing with a pair of spring clamps one on each end... should last a fairly long time.
Since some tubing is rather flexible it can likely be stretched to fit a wider diameter, and then the smaller diameter can be the one that needs a clamp... this is a fast substitute for a fancy shaft coupler... also sucks up the alignment difference nicely.

                            _-_-bear
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_-_- bear WB2GCR                   http://www.bearlabs.com
wd5jwy
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« Reply #11 on: February 20, 2010, 08:51:22 PM »

Leeds Radio - Shaft coupler, phenolic for 1/4"shafts                $6.00

http://www.leedselect.com/generalinfo.html#contact_us

Click on the "Hardware" link and scroll down.
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KB3DKS
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« Reply #12 on: February 22, 2010, 03:10:10 AM »

Steph,
 I have a parts drawer full of various couplers. Since several here have mentioned that the shaft sizes are not both 1/4" how about checking and reply here or PM me.
 Meanwhile will take an inventory.
Worst case a 1/4-1/4 can be turned out to fit whatever. I can do that too.

Bill, KB3DKS in 1 Land
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WA5VGO
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« Reply #13 on: February 22, 2010, 07:36:03 AM »

Every Johnson VFO coupling I've seen is 1/4" on the drive end and 3/16" on the capacitor end.

Darrell
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Rob K2CU
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« Reply #14 on: February 22, 2010, 11:04:35 AM »

You can probably repair the crack in the phenolic with super glue. only a tiny drop is needed. Let it totally dry overnight. If you need to replace the phenolic piece, you could use half thinckness (0.032) G10 pcb stock with out the copper cladding. I have a few small pieces if you want. I used the trick of buying the nylon spacers from my local ace hardware along with four #10 allen key set screws and a tap. undersize the drill hole before tapping. Don't overtighten. I used two of these in place of the metal couplers on the driver tune and loading cap shafts.

when I rebuilt my Valiant, I had a stickey reduction unit. I knew that if I did manage to get it apart, it would happen such that tiny blass would be flying everywhere and turn out to be unobtainium. I just flushed WD-40 through it multiple times and them used a low speed drill motor to spin it and work out the old lubrication as it was flushed with the WD-40. when I got it totally cleaned out, I just filled it with light oil by applying it to the joint. I figured that grease would just dry up again. So far the oil works fine.

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WQ9E
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« Reply #15 on: February 22, 2010, 11:48:49 AM »



when I rebuilt my Valiant, I had a stickey reduction unit. I knew that if I did manage to get it apart, it would happen such that tiny blass would be flying everywhere and turn out to be unobtainium. I just flushed WD-40 through it multiple times and them used a low speed drill motor to spin it and work out the old lubrication as it was flushed with the WD-40. when I got it totally cleaned out, I just filled it with light oil by applying it to the joint. I figured that grease would just dry up again. So far the oil works fine.



Rob,

The VFO drive is actually easy to take apart and put together and the only part that might come loose and get lost are the standard size, easily replaceable ball bearings.  Getting the reduction unit out is much more difficult than dis/re-assembly.

I drop the bearings and housing in a cup with a bit of WD-40 to remove the old grease and then I dry it thoroughly with a clean paper towel.  I use the same synthetic lube (from Farm and Fleet) that I use for my tractor and pickup suspension and it should last a very long time without drying.  The lube will hold the balls in place while it is assembled.

The only "trick" is to adjust the tension properly which is set by how tightly you screw the case halves together.  Too tight and it is stiff while too loose will lead to slippage.  It isn't that critical and is easy to reset if you miss the initial setting but I can only recall one occasion where I had to reset one (due to slippage).  I have cleaned the drives on both my Valiant 1's, a Valiant 2, Ranger 1, Ranger 2, Pacemaker, and 500 without failure.  I am certainly not a "master mechanic" so if I can do that many without a problem I don't believe you or anyone else will have a problem either.
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Rodger WQ9E
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« Reply #16 on: February 23, 2010, 10:33:28 AM »

Very good solutions

BUT don't use a CD! They are not friendly and will just shatter. It's a very different type of plastic

Fred
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AB2EZ
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« Reply #17 on: February 24, 2010, 11:20:47 AM »

Duplicated earlier message regarding Leeds as a source

SDP
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Stewart ("Stu") Personick
Pictured: Cartoon from The New Yorker: "Season's Greetings" looks OK to me. Let's run it by the legal department
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