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Vintage Amateur and Military Radio Amateur/military receivers and transmitters, morse, and any other related vintage comms equipment. |
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25th Sep 2018, 9:21 pm | #1 |
Heptode
Join Date: May 2014
Location: Salisbury, Wiltshire, UK.
Posts: 998
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Old rotator
I was recently given an old Ham 2 or Ham M series 5 rotator from the 38th week in 1976!!
I have stripped it and cleaned it and everything works, its ready for new bearings...alas, the motor is seized solid. Very sad. Its now covered in wd40 and sat in a dish of coke. Much frequent waggling of the shaft, I am.told, works wonders. Frankly, I doubt it...but having got thus far I ought to try a few weeks. A replacement motor will cost me 70 USD. I bet for a hundred quid I could get it going...but it'll still be a rotator from the 38th week of the year of the heatwave. David |
25th Sep 2018, 10:06 pm | #2 |
Dekatron
Join Date: Apr 2012
Location: Worksop, Nottinghamshire, UK.
Posts: 5,553
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Re: Old rotator
Have you got a photo of the seized bearing?
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25th Sep 2018, 10:14 pm | #3 |
Dekatron
Join Date: Apr 2009
Location: Oxfordshire, UK.
Posts: 4,934
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Re: Old rotator
The problem there is that WD40 is a hydrocarbon water repellent and will therefore tend to keep the cola from getting where it needs to be.
Is the whole motor immersed or have you got the bearings out? As a means of breaking loose corrosion products, I'd definitely go for citric acid solution or even vinegar in preference to cola. Worth persevering with! B
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Saturn V had 6 million pounds of fuel. It would take thirty thousand strong men to lift it an inch. |
25th Sep 2018, 10:27 pm | #4 |
Heptode
Join Date: Oct 2015
Location: Gloucestershire, UK.
Posts: 719
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Re: Old rotator
A Water Dispersant will hinder, not help. Try a penetrating oil, something like a 50:50 Acetone/ATF mixture. Even a drop of diesel would do at a pinch.
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26th Sep 2018, 1:36 am | #5 |
Nonode
Join Date: Oct 2010
Location: Tintinara, South Australia, Australia
Posts: 2,339
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Re: Old rotator
If the cola or any acid gets onto the enamel of the motor windings, it's a new motor you'll be needing regardless.
Yes, been there, done that. Not a pretty sight. |
26th Sep 2018, 2:12 am | #6 |
Dekatron
Join Date: Jan 2012
Location: Brentwood, Essex, UK.
Posts: 5,337
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Re: Old rotator
Lighter fluid, such as Ronsonol, can work miracles on severely seized moving parts. You can use ordinary petrol at a pinch, but lighter fluid does not have the nasty additives that you get in motor spirit.
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26th Sep 2018, 2:52 am | #7 | |
Dekatron
Join Date: Apr 2009
Location: Oxfordshire, UK.
Posts: 4,934
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Re: Old rotator
Quote:
Citric and vinegar (acetic) are both dilute and weak acids (note the distinction) and I'd be even more amazed if they attacked traditional enamel. Of course, any of these substances would attack un-protected copper. All that said, if you get the stage where you're putting aqueous solutions of any kind in to the windings, I'd say that you'd need to be sure that you got it all out before applying any power. B
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Saturn V had 6 million pounds of fuel. It would take thirty thousand strong men to lift it an inch. |
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26th Sep 2018, 5:59 am | #8 |
Nonode
Join Date: Oct 2010
Location: Tintinara, South Australia, Australia
Posts: 2,339
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Re: Old rotator
Agreed, but the problem arose where the enamel had been removed from the copper to make the connections to the armature/commutator.
stuff ate through the copper at that point, rendering the motor useless (I didn't bother fixing it as it really needed a new gear as well). Like Davids, it had seized and was sat immersed in cola for quite a while, which did clean it all up nicely by the way. This would have been 30-35 years ago, reason it sticks in the brain is because I actually paid for the rotator as part of a tower/antenna deal. Oh well, live and learn. |
26th Sep 2018, 4:25 pm | #9 |
Heptode
Join Date: May 2014
Location: Salisbury, Wiltshire, UK.
Posts: 998
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Re: Old rotator
I'll get a photo of the bearing but a rotator repair specialist reckons the stator and rotor laminations will have rusted together.
I might be persuaded to buy a new motor. At 60 USD it's not cheap for a motor, but it is for a braked rotator. |
26th Sep 2018, 4:39 pm | #10 | |
Dekatron
Join Date: Apr 2012
Location: Wiltshire, UK.
Posts: 13,996
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Re: Old rotator
Quote:
[I once tried to separate the stator and rotor of an old 'Smiths' car heater-motor that had filled up with water: it defeated an 8-ton hydraulic press] |
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26th Sep 2018, 5:25 pm | #11 |
Heptode
Join Date: May 2014
Location: Salisbury, Wiltshire, UK.
Posts: 998
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Re: Old rotator
Ouch.
Yes, it sounds final IF that's what it is |
26th Sep 2018, 6:14 pm | #12 |
Heptode
Join Date: May 2014
Location: Salisbury, Wiltshire, UK.
Posts: 998
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Re: Old rotator
Here are some pics of the unit. I note that the circumferencial laminations are buckled in the vertical plane...I can't imagine they were made like this so this could be a sign of great rust induced stress!
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26th Sep 2018, 6:29 pm | #13 |
Dekatron
Join Date: Apr 2012
Location: Wiltshire, UK.
Posts: 13,996
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Re: Old rotator
That does not look good. I'd be inclined to subject it to the Royal Navy flotation test //[1]\\ and if it fails, buy a new one.
"Oxide jacking" as it's known has in the last few decades been a big issue in things like motorway flyovers, where rusting of the steel reinforcing-rods in concrete bursts the concrete asunder and led to hundreds of millions of pounds in repair-bills. It's also been a nightmare for residents of 1940s/50s-build reinforced-concrete council-houses. //[1]\\ Hurl the part-under-test into the nearest body of deep water. If it floats, recover it and use it. |
26th Sep 2018, 6:50 pm | #14 |
Heptode
Join Date: May 2014
Location: Salisbury, Wiltshire, UK.
Posts: 998
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Re: Old rotator
Thanks. Rather as I feared.
Looking at the Hygain / MFJ catalogue, the motor is 69 dollars and the potentiometer at the top a further 39, but that works so shouldn't be needed. The bolts that fasten the two together will though. d |
26th Sep 2018, 6:58 pm | #15 |
Dekatron
Join Date: Apr 2012
Location: Worksop, Nottinghamshire, UK.
Posts: 5,553
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Re: Old rotator
That motor looks like the rust has gone rusty.
Rust contains oxygen that has been absorbed during the rusting process so steel gets bigger as it rusts. Concrete does fail due to the steel rusting inside the columns. Rust claimed junction 19 on the M1 so that they had to fully rebuild all of the elevated parts. |
26th Sep 2018, 7:01 pm | #16 | |
Heptode
Join Date: May 2014
Location: Salisbury, Wiltshire, UK.
Posts: 998
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Re: Old rotator
Quote:
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26th Sep 2018, 7:03 pm | #17 |
Dekatron
Join Date: Apr 2012
Location: Worksop, Nottinghamshire, UK.
Posts: 5,553
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Re: Old rotator
No it is a duffer
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26th Sep 2018, 7:12 pm | #18 |
Tetrode
Join Date: Feb 2012
Location: Bishop Auckland, County Durham, UK.
Posts: 92
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Re: Old rotator
Hi David I have a scrap hygain ham 4 rotator, as I’ve upgraded to heavier duty rotators here. It’s yours if you want it. I also have a new rotation pot. Drop me a line.
Cheers andy |
26th Sep 2018, 7:43 pm | #19 |
Heptode
Join Date: May 2014
Location: Salisbury, Wiltshire, UK.
Posts: 998
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Re: Old rotator
Done.
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27th Sep 2018, 8:14 am | #20 |
Heptode
Join Date: May 2014
Location: Salisbury, Wiltshire, UK.
Posts: 998
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Re: Old rotator
A case for not screwing amateur pa transistors up to 150pc of their stated output I think. 20w ft 817 anyone?
D |