Motor for Yaesu G5500 Azimuth Rotator?
Hi Everyone,
Well I'll be QRT from the sats for a little while!! After replacing my UHF antenna on the backyard satellite array, I managed to catch the (slightly longer) new antenna on the house roof and jammed the Yaesu G-5500 rotator, ugh! Even though I had replaced the normal 2-amp fuses in the controller with 1-amp fuses, the azimuth motor still managed to overheat and burn out.
I disassembled the azimuth rotator, and although the gears, bearings, switches, and capacitor are all OK, the motor has quite a burnt smell. Bench-testing the unit with motor removed from the assembly shows the motor doesn't spin at all in one direction, and spins slowly but draws high current in the other. Coil windings are in series for left/right, should be 3.5 + 3.5 = 7.0 ohms, and the right coil is showing only 1.0 ohms resistance. The azimuth motor is definitely toast. Fortunately, the controller is OK (both the Az and El sides of the controller successfully control the elevation rotator).
I just got off the phone with Yaesu parts, and unfortunately the replacement motor has been backordered from Japan since December. No estimate yet of when more might come in.
Question to the list: does anyone have a G5500 azimuth rotator with a working motor available for parts? Or any other ideas for replacement?
73! Dave KB5WIA
Hi David, As you found out shaded pole motors do not pull more current when they stall, they actually pull less and so they wont blow the fuse, they just sit and cook. So while your changing the motor now might be a good time to put 2 thermal cutout switches inside on the windings so this doesn't happen again,it takes two, one for each direction.
http://www.devale.com/battery-protection/miniature-bimetal-snap-disc.html or http://www.pepiusa.com/prod.html
explains them, and you can find them in small quantities at
http://www.allelectronics.com/make-a-store/category/765/Thermal-Fuses-Breake...
or at other places...
73 Kevin WA6FWF
On 2/23/2012 6:31 AM, David Palmer KB5WIA wrote:
Hi Everyone,
Well I'll be QRT from the sats for a little while!! After replacing my UHF antenna on the backyard satellite array, I managed to catch the (slightly longer) new antenna on the house roof and jammed the Yaesu G-5500 rotator, ugh! Even though I had replaced the normal 2-amp fuses in the controller with 1-amp fuses, the azimuth motor still managed to overheat and burn out.
I disassembled the azimuth rotator, and although the gears, bearings, switches, and capacitor are all OK, the motor has quite a burnt smell. Bench-testing the unit with motor removed from the assembly shows the motor doesn't spin at all in one direction, and spins slowly but draws high current in the other. Coil windings are in series for left/right, should be 3.5 + 3.5 = 7.0 ohms, and the right coil is showing only 1.0 ohms resistance. The azimuth motor is definitely toast. Fortunately, the controller is OK (both the Az and El sides of the controller successfully control the elevation rotator).
I just got off the phone with Yaesu parts, and unfortunately the replacement motor has been backordered from Japan since December. No estimate yet of when more might come in.
Question to the list: does anyone have a G5500 azimuth rotator with a working motor available for parts? Or any other ideas for replacement?
73! Dave KB5WIA _______________________________________________ Sent via [email protected]. Opinions expressed are those of the author. Not an AMSAT-NA member? Join now to support the amateur satellite program! Subscription settings: http://amsat.org/mailman/listinfo/amsat-bb
Thanks Drew, Dee, and Kevin!
Yes, I definitely plan to add a thermal switch to the replacement motor on the rebuild -- hopefully to prevent such a thing from happening again, ugh!
Mike WA6ARA suggested a company down in LA that rewinds motors -- I sent them a description, and they wrote back at 11pm last night (!) saying that there would be no problem with this one, but to send it down so they could take a look and give a quote. So .. the defective motor is on its way down there now.
I'd still like to get a replacement of some sort, whether or not the rewind is successful -- can anyone confirm if the G5400 azimuth rotator motor will physically fit in the G5500 gear assembly? I know the capacitor is inboard in the '5500 and at the controller on the '5400, but are the two motors physically similar?
Thanks everyone!
Dave KB5WIA
On 2/23/12 8:29 AM, WA6FWF wrote:
Hi David, As you found out shaded pole motors do not pull more current when they stall, they actually pull less and so they wont blow the fuse, they just sit and cook.
Are you sure these are shaded-pole motors? They're designed for a single-phase supply and are not normally reversible. Nor do they provide much starting torque, which you need in a rotor. They're common in small appliances, especially fans.
The motors in these Kenpro/Yaesu rotors are 2-phase (presumably quadrature), reversible, capacitor-run, AC induction motors. You control direction by applying 24V AC directly to one stator winding and to the other through a phase shift capacitor. In the older Kenpro design that I have, the capacitor is in the control box. In the newer Yaesu models, it's in the rotor. I'm not sure but I think this may have been to provide limit switches to protect the motor.
The running capacitor advances the phase of the current in the second stator winding to establish the rotating magnetic field that drags the rotor in the desired direction. The phase shift isn't quite 90 degrees, nor are the two phase currents the same, so the motor doesn't run as efficiently as it would on an ideal 2-phase supply. Like most induction motors it should draw quite a bit of current when stalled so Dave's fuses were probably just too large.
I'm working on a variable frequency, variable voltage drive for these rotors that changes the frequency and voltage together to vary speed. The main thing I'm after is the ability to run the rotor continuously at whatever speed is required to avoid constant starts and stops that stress the motors, shake the antenna hardware loose, and increase the average pointing error.
The torque curve of a classic induction motor has zero torque at synchronous speed, increasing as the rotor slips under load below synchronous speed and eventually reaching a breakaway peak. When this happens with most loads, the result is a motor stall. Lowering the drive frequency reduces the breakaway speed and increasing stall torque, so starting at low frequency will greatly increase starting torque at the same time greatly lowering the motor drive current.
These variable frequency/variable voltage AC motor drives have long been common in industry, and they've become the standard in hybrid and newer electric cars. Only a few cars like the Tesla actually use induction motors; most now use permanent magnet rotors but the principles are much the same except that a permanent magnet motor has no slip. This would make it easier to keep track of position in an antenna rotor, but there's still the potentiometer, assuming it's calibrated.
--Phil
Sorry my mistake, been looking at shaded pole motors for a SB-200 amp and it stuck...
Yes you are correct AC induction with a capacitor providing the phase shift, when I was making a board to connect to a LVB controller to totally do away with the G-5500 control box I measured the current while running and then measured it locked and to my surprise the current was actually less.
I have had other people tell me that this happens because the cap is too small or inefficiencies in the motor itself and it would not act this way in a larger motor.
Based on the number of burned out motors and transformers and perfectly good fuses left over, there is something going on.
I was originally measuring it to find the values so I could put a PTC in to protect it, the current dropping instead of going up ruled that out, so I went with the thermal approach instead.
73 Kevin WA6FWF
On 2/23/2012 12:23 PM, Phil Karn wrote:
On 2/23/12 8:29 AM, WA6FWF wrote:
Hi David, As you found out shaded pole motors do not pull more current when they stall, they actually pull less and so they wont blow the fuse, they just sit and cook.
Are you sure these are shaded-pole motors? They're designed for a single-phase supply and are not normally reversible. Nor do they provide much starting torque, which you need in a rotor. They're common in small appliances, especially fans.
The motors in these Kenpro/Yaesu rotors are 2-phase (presumably quadrature), reversible, capacitor-run, AC induction motors. You control direction by applying 24V AC directly to one stator winding and to the other through a phase shift capacitor. In the older Kenpro design that I have, the capacitor is in the control box. In the newer Yaesu models, it's in the rotor. I'm not sure but I think this may have been to provide limit switches to protect the motor.
The running capacitor advances the phase of the current in the second stator winding to establish the rotating magnetic field that drags the rotor in the desired direction. The phase shift isn't quite 90 degrees, nor are the two phase currents the same, so the motor doesn't run as efficiently as it would on an ideal 2-phase supply. Like most induction motors it should draw quite a bit of current when stalled so Dave's fuses were probably just too large.
I'm working on a variable frequency, variable voltage drive for these rotors that changes the frequency and voltage together to vary speed. The main thing I'm after is the ability to run the rotor continuously at whatever speed is required to avoid constant starts and stops that stress the motors, shake the antenna hardware loose, and increase the average pointing error.
The torque curve of a classic induction motor has zero torque at synchronous speed, increasing as the rotor slips under load below synchronous speed and eventually reaching a breakaway peak. When this happens with most loads, the result is a motor stall. Lowering the drive frequency reduces the breakaway speed and increasing stall torque, so starting at low frequency will greatly increase starting torque at the same time greatly lowering the motor drive current.
These variable frequency/variable voltage AC motor drives have long been common in industry, and they've become the standard in hybrid and newer electric cars. Only a few cars like the Tesla actually use induction motors; most now use permanent magnet rotors but the principles are much the same except that a permanent magnet motor has no slip. This would make it easier to keep track of position in an antenna rotor, but there's still the potentiometer, assuming it's calibrated.
--Phil
Just as a follow on, I stuck a watt meter on the controller I have (LVB and custom driver board) 2-3 watts idle approx 51 watts turning in AZ or EL, 48 watts stalled in one direction 56 watts stalled the other way in AZ, 56 watts stalled up 50 watts stalled down in EL, so slightly less or slightly more or about the same, no matter how you cut it not enough difference to be able to fuse for it. I always thought a timeout in the LVB code might be nice, I'm driving but the numbers are not changing might be nice... but in the meantime the thermals will work..
73 Kevin WA6FWF
On 2/23/2012 4:06 PM, WA6FWF wrote:
Sorry my mistake, been looking at shaded pole motors for a SB-200 amp and it stuck...
Yes you are correct AC induction with a capacitor providing the phase shift, when I was making a board to connect to a LVB controller to totally do away with the G-5500 control box I measured the current while running and then measured it locked and to my surprise the current was actually less.
I have had other people tell me that this happens because the cap is too small or inefficiencies in the motor itself and it would not act this way in a larger motor.
Based on the number of burned out motors and transformers and perfectly good fuses left over, there is something going on.
I was originally measuring it to find the values so I could put a PTC in to protect it, the current dropping instead of going up ruled that out, so I went with the thermal approach instead.
73 Kevin WA6FWF
On 2/23/2012 3:23 PM, Phil Karn wrote:
These variable frequency/variable voltage AC motor drives have long been common in industry, and they've become the standard in hybrid and newer electric cars.
Phil,
Your fans will not be completely happy until your controller runs a state-space model of the motor/antenna system, with software that is careful to generate acceleration and jerk limited commands such that mechanical resonances are not excited.
With tongue firmly in cheek -Joe KM1P
On 2/24/12 11:58 AM, Joe Fitzgerald wrote:
Your fans will not be completely happy until your controller runs a state-space model of the motor/antenna system, with software that is careful to generate acceleration and jerk limited commands such that mechanical resonances are not excited.
With tongue firmly in cheek
What do you mean? That's exactly my plan. Fortunately, the problem of tracking a LEO satellite with a deadband of 5-10 degrees is a very non-demanding problem. That's why most hams are still doing it with primitive, bang-bang control.
But I think we can do a lot better. It's time to get serious about moving to the microwave bands. That will require one thing on both the ground and in space: much tighter antenna pointing. But the payoffs will be enormous: much smaller and lighter ground antennas that will be practical for many more hams, much better signal-to-noise ratios, and much higher bandwidths and data rates.
All this could mean substantial growth for AMSAT. But we'll have to let go of not only inefficient analog modulation but also the low frequency bands, especially 2m.
On 2/24/2012 8:14 PM, Phil Karn wrote:
Fortunately, the problem of tracking a LEO satellite with a deadband of 5-10 degrees is a very non-demanding problem. That's why most hams are still doing it with primitive, bang-bang control.
I had occasion to install a Pro-sis-tel rotor for a nearby ham a while back. I beleve they presently ship with DC motors, but early models had a little (by industrial standards) three phase motor .. I think 1/8th horsepower. I did not have a chance to reverse engineer their controller, but it was not particularly sophisticated. They simply pulsed 60Hz AC from a 24V transformer when they wanted to accelerate or slow down. I am not exactly sure how they generated torque since there was no evidence that they did anything to shift the phase of the three windings. Of course my imagination started thinking about using industrial variable speed drives with it. The long cable from the shack to the tower is a concern ... most industrial drives specify a length limit to to the motor in an effort to minimize reactance. I suppose you could put the power electronics at the rotor, but lightning concerns give me pause.
-Joe
On 2/25/12 6:46 AM, Joe Fitzgerald wrote:
controller, but it was not particularly sophisticated. They simply pulsed 60Hz AC from a 24V transformer when they wanted to accelerate or slow down. I am not exactly sure how they generated torque since there was no evidence that they did anything to shift the phase of the three windings.
If it really was a 3-phase induction motor then there *had* to be some sort of phase shift at least to start it. An induction motor connected to a single-phase supply has no starting torque, so it'll just sit there and burn out unless some sort of protection circuit kicks in first. If you give it a twist in one direction or the other, it'll start and continue to run in that direction.
This suggests a possible failure mode for these Yaesu/Kenpro antenna rotors: if the run capacitor fails or the connection to one winding opens.
Most induction motors designed for single-phase supplies (like these rotor motors) are actually 2-phase motors. The second winding connects to the supply through a phase shift capacitor either permanently ("capacitor run") or disconnected with a centrifugal switch once the motor starts ("capacitor start").
People usually think of 3-phase induction motors as industrial-sized behemoths, but one especially common application is in the so-called "brushless DC motor". They're actually AC induction or permanent magnet motors with built in inverters producing 3-phase AC at a frequency set by a sensor (usually Hall effect) on the rotor.
One could argue that there really is no such thing as a "DC motor" except for Faraday's homopolar motor that's still not much more than a curiosity. So-called "DC" motors are really AC motors with built-in DC-AC conversion.
On 2/25/2012 4:25 PM, Phil Karn wrote:
If it really was a 3-phase induction motor then there *had* to be some sort of phase shift at least to start it.
Of course you are right. I found a schematic of their controller
http://www.ecse.rpi.edu/courses/CStudio/ham_radio_docs/Prosistel61C.pdf
The phase shift is done with C7 and C8, but I have to spend some time with the schematic to figure out exactly what they are doing. I expected to see a microcontroller/DSP individually controlling each of the 3 legs.
-Joe KM1P
On 2/25/12 9:24 PM, Joe Fitzgerald wrote:
On 2/25/2012 4:25 PM, Phil Karn wrote:
If it really was a 3-phase induction motor then there *had* to be some sort of phase shift at least to start it.
Of course you are right. I found a schematic of their controller
http://www.ecse.rpi.edu/courses/CStudio/ham_radio_docs/Prosistel61C.pdf
The phase shift is done with C7 and C8, but I have to spend some time with the schematic to figure out exactly what they are doing. I expected to see a microcontroller/DSP individually controlling each of the 3 legs.
They do not show the internal wiring of the motor, but the controller strongly suggests this is simply a 2-phase capacitor-run motor just like the Yaesu/Kenpro models, except operating on 48V AC rather than 24V AC. The run capacitor is formed by C7 and C8 in series, and pin F1 on the motor is the common return (neutral) for the two windings. Switching is done with electrically isolated triacs (AC switches) rather than relays.
BTW, this shows some of the reasons 2-phase AC eventually fell out of favor in the power grid. Both require 3 wires but they don't use them as efficiently. In the 2-phase system, two wires are hot phases and the third is a (usually grounded) neutral wire. If the two phases each carry 1 A, then the neutral returns 1.4A. (Sum currents 90 degrees out of phase and the total is the square root of the sum of the squares.) If each hot phase is 1V to ground, then the total power transferred over the 3 wires is 2 watts.
A true 3-phase motor has 3 windings connected in wye or delta to the three terminals in a symmetrical way. You'd need a 4th wire to provide a neutral, but because the phase currents are balanced they cancel in the neutral and you can do without it. If each wire draws 1A and is 1V from ground, then together they carry 3W -- one more watt than the 2-phase system even though the 2-phase system's third wire has to be heavier to carry 1.4A.
This is why 3-phase power became *the* grid standard. But for some reason, the guy who originally invented 2-phase AC is the one we generally credit for our use today of 3-phase. Maybe that's because most people wouldn't want to get into a 1.5 Dolivo-Dobrovolsky MRI machine at the local radiology clinic. "1.5 Tesla MRI machine" sounds a lot cooler.
Efficient use of wire isn't as important in a rotator system as in a power grid, so a 2-phase motor is easier to run as a reversible motor on a single-phase supply than a 3-phase motor would be. But if I were to design a rotor system completely from scratch I'd probably use a 3-phase motor driven by a 3-phase motor variable inverter/controller.
--Phil
Hi,
I've been interested in this thread as I have a shorted G5500 elevation motor. I reported this several months ago, and found that it was a fairly common problem.
I'm waiting for warmer WX when I plan to replace it. I'm wondering whether there have been any reports of the over heating being caused by failure of the yahoo control unit or tracker interface. Perhaps sticking relays or electronics. I'm using the LVB tracker.
I can see some situations where the micro-switches inside the rotator could fail to prevent damage.
The thermal cut-outs suggested earlier in this thread looks attractive. I was also thinking about a PIC solution. As these rotators are now very expensive, and it's a major task for me to install the replacement, I don't want to risk another burned out motor.
Any thoughts?
73 Clive G3CWV
Hitchin, North Hertfordshire, UK
----- Original Message ----- From: "Phil Karn" [email protected] To: "Joe Fitzgerald" [email protected] Cc: [email protected] Sent: Saturday, February 25, 2012 10:25 PM Subject: [amsat-bb] Re: Motor for Yaesu G5500 Azimuth Rotator?
On 2/25/12 6:46 AM, Joe Fitzgerald wrote:
controller, but it was not particularly sophisticated. They simply pulsed 60Hz AC from a 24V transformer when they wanted to accelerate or slow down. I am not exactly sure how they generated torque since there was no evidence that they did anything to shift the phase of the three windings.
If it really was a 3-phase induction motor then there *had* to be some sort of phase shift at least to start it. An induction motor connected to a single-phase supply has no starting torque, so it'll just sit there and burn out unless some sort of protection circuit kicks in first. If you give it a twist in one direction or the other, it'll start and continue to run in that direction.
This suggests a possible failure mode for these Yaesu/Kenpro antenna rotors: if the run capacitor fails or the connection to one winding opens.
Most induction motors designed for single-phase supplies (like these rotor motors) are actually 2-phase motors. The second winding connects to the supply through a phase shift capacitor either permanently ("capacitor run") or disconnected with a centrifugal switch once the motor starts ("capacitor start").
People usually think of 3-phase induction motors as industrial-sized behemoths, but one especially common application is in the so-called "brushless DC motor". They're actually AC induction or permanent magnet motors with built in inverters producing 3-phase AC at a frequency set by a sensor (usually Hall effect) on the rotor.
One could argue that there really is no such thing as a "DC motor" except for Faraday's homopolar motor that's still not much more than a curiosity. So-called "DC" motors are really AC motors with built-in DC-AC conversion.
Hi Phil, KA9Q
If you are interested in a very simple but effective "Single to 3-PHASE Power Converter for azimuth and elevation motors currently used for EME, look at this web page made by John Yurek, K3PGP
http://www.k3pgp.org/3phconv.htm
73" de
i8CVS Domenico
On 2/26/12 3:02 AM, i8cvs wrote:
If you are interested in a very simple but effective "Single to 3-PHASE Power Converter for azimuth and elevation motors currently used for EME, look at this web page made by John Yurek, K3PGP
This is a classic "rotary phase converter" that uses a surplus 3-phase 'idler' motor to generate something resembling 3-phase AC from a single phase utility supply. The idler motor itself needs a starting mechanism; this one seems to do it with running capacitors but I've also seen it done with a separate single-phase starting motor.
These things are commonly homebrewed to run 3-phase machine shop tools when a 3-phase utility feed isn't available. They usually work well enough, but the output is not ideal 3-phase AC.
It's also fixed frequency. A variable frequency supply is what you really want when driving antennas.
The last couple of summers I did some Algonquin Park canoe/backpak trips and put some unique grids on the sats with a portable setup using a handheld, android tablet, and mini personal computer. I powered all of them from a small 12v gelcell battery charged with a small solar panel.
This year I am doing some different travel experiences and see no need for these units and have placed them on eBay (where else).
The numbers are:
180827160049 - personal mini computer
180827161919 - android tablet
Thanks for the space and your time......
On 2/23/12 6:31 AM, David Palmer KB5WIA wrote:
Question to the list: does anyone have a G5500 azimuth rotator with a working motor available for parts? Or any other ideas for replacement?
You might consider rewinding it yourself. I did that with one of mine some years ago, and it worked well enough that I left it in place when the replacement I'd ordered finally arrived.
I'm working on a variable speed drive for these rotors, and this suggests that I should detect motor stalls. That really shouldn't be too hard. I could do it either by noticing that the rotor is turning more slowly than it should, or by monitoring the current and seeing that it's higher than usual. Motors are usually pretty rugged so an instant reaction probably isn't necessary. My drive should be more efficient than the standard fixed-frequency 60 Hz capacitor-run drive so the motors should run cooler anyway.
Phil
Hi Dave I have rewound the motors. It take a couple of hours but is doable. I went to Radio shack and bought I think # 24 or 26 gale wire.
nick
-----Original Message----- From: [email protected] [mailto:[email protected]] On Behalf Of David Palmer KB5WIA Sent: Thursday, February 23, 2012 8:32 AM To: AMSAT BB Subject: [amsat-bb] Motor for Yaesu G5500 Azimuth Rotator?
Hi Everyone,
Well I'll be QRT from the sats for a little while!! After replacing my UHF antenna on the backyard satellite array, I managed to catch the (slightly longer) new antenna on the house roof and jammed the Yaesu G-5500 rotator, ugh! Even though I had replaced the normal 2-amp fuses in the controller with 1-amp fuses, the azimuth motor still managed to overheat and burn out.
I disassembled the azimuth rotator, and although the gears, bearings, switches, and capacitor are all OK, the motor has quite a burnt smell. Bench-testing the unit with motor removed from the assembly shows the motor doesn't spin at all in one direction, and spins slowly but draws high current in the other. Coil windings are in series for left/right, should be 3.5 + 3.5 = 7.0 ohms, and the right coil is showing only 1.0 ohms resistance. The azimuth motor is definitely toast. Fortunately, the controller is OK (both the Az and El sides of the controller successfully control the elevation rotator).
I just got off the phone with Yaesu parts, and unfortunately the replacement motor has been backordered from Japan since December. No estimate yet of when more might come in.
Question to the list: does anyone have a G5500 azimuth rotator with a working motor available for parts? Or any other ideas for replacement?
73! Dave KB5WIA _______________________________________________ Sent via [email protected]. Opinions expressed are those of the author. Not an AMSAT-NA member? Join now to support the amateur satellite program! Subscription settings: http://amsat.org/mailman/listinfo/amsat-bb
I have rewound a few of these motor coils and a #24 to #26 gauge enamel wire should work. A #22 gauge enamel wire would be too large and you would not be able to wind the same number of turns.
It is the breakdown of the enamel due to wire heating that makes them fail by creating a short circuit in the windings.
Tim - N8DEU
----- Original Message ----- From: "Nick Pugh" [email protected] To: "'David Palmer KB5WIA'" [email protected]; "'AMSAT BB'" [email protected] Sent: Thursday, February 23, 2012 4:09 PM Subject: [amsat-bb] Re: Motor for Yaesu G5500 Azimuth Rotator?
Hi Dave I have rewound the motors. It take a couple of hours but is doable. I went to Radio shack and bought I think # 24 or 26 gale wire.
nick
-----Original Message----- From: [email protected] [mailto:[email protected]] On Behalf Of David Palmer KB5WIA Sent: Thursday, February 23, 2012 8:32 AM To: AMSAT BB Subject: [amsat-bb] Motor for Yaesu G5500 Azimuth Rotator?
Hi Everyone,
Well I'll be QRT from the sats for a little while!! After replacing my UHF antenna on the backyard satellite array, I managed to catch the (slightly longer) new antenna on the house roof and jammed the Yaesu G-5500 rotator, ugh! Even though I had replaced the normal 2-amp fuses in the controller with 1-amp fuses, the azimuth motor still managed to overheat and burn out.
I disassembled the azimuth rotator, and although the gears, bearings, switches, and capacitor are all OK, the motor has quite a burnt smell. Bench-testing the unit with motor removed from the assembly shows the motor doesn't spin at all in one direction, and spins slowly but draws high current in the other. Coil windings are in series for left/right, should be 3.5 + 3.5 = 7.0 ohms, and the right coil is showing only 1.0 ohms resistance. The azimuth motor is definitely toast. Fortunately, the controller is OK (both the Az and El sides of the controller successfully control the elevation rotator).
I just got off the phone with Yaesu parts, and unfortunately the replacement motor has been backordered from Japan since December. No estimate yet of when more might come in.
Question to the list: does anyone have a G5500 azimuth rotator with a working motor available for parts? Or any other ideas for replacement?
73! Dave KB5WIA _______________________________________________ Sent via [email protected]. Opinions expressed are those of the author. Not an AMSAT-NA member? Join now to support the amateur satellite program! Subscription settings: http://amsat.org/mailman/listinfo/amsat-bb
Sent via [email protected]. Opinions expressed are those of the author. Not an AMSAT-NA member? Join now to support the amateur satellite program! Subscription settings: http://amsat.org/mailman/listinfo/amsat-bb
On 2/23/12 2:51 PM, Tim Cunningham wrote:
I have rewound a few of these motor coils and a #24 to #26 gauge enamel wire should work. A #22 gauge enamel wire would be too large and you would not be able to wind the same number of turns.
It is the breakdown of the enamel due to wire heating that makes them fail by creating a short circuit in the windings.
I don't remember the wire size I used (it's been over 20 years) but you're right about the short circuit. Just one shorted turn will form the shorted secondary of a transformer, and the I^2R losses in that turn will create quite a bit of heat that will further damage the insulation on the nearby windings until the whole thing is toast.
Just a quick update -- Yaesu Parts just emailed me and advised that they don't think any of the motors from other rotators are directly compatible with the G5500 azimuth motor -- the estimate on arrival time of more stock is uncertain, possibly 4-6 weeks or longer.
I haven't sourced a direct replacement motor yet; the original motor was sent down to Eurton Electric yesterday for rewinding, hopefully I'll have a quote and time estimate for that soon.
73!
Dave KB5WIA
On Fri, Feb 24, 2012 at 4:26 PM, Phil Karn [email protected] wrote:
On 2/23/12 2:51 PM, Tim Cunningham wrote:
I have rewound a few of these motor coils and a #24 to #26 gauge enamel wire should work. A #22 gauge enamel wire would be too large and you would not be able to wind the same number of turns.
It is the breakdown of the enamel due to wire heating that makes them fail by creating a short circuit in the windings.
I don't remember the wire size I used (it's been over 20 years) but you're right about the short circuit. Just one shorted turn will form the shorted secondary of a transformer, and the I^2R losses in that turn will create quite a bit of heat that will further damage the insulation on the nearby windings until the whole thing is toast.
----- Original Message ----- From: "Phil Karn" [email protected] To: "Tim Cunningham" [email protected] Cc: "'AMSAT BB'" [email protected] Sent: Saturday, February 25, 2012 1:26 AM Subject: [amsat-bb] Re: Motor for Yaesu G5500 Azimuth Rotator?
On 2/23/12 2:51 PM, Tim Cunningham wrote:
I have rewound a few of these motor coils and a #24 to #26 gauge enamel wire should work. A #22 gauge enamel wire would be too large and you would not be able to wind the same number of turns.
It is the breakdown of the enamel due to wire heating that makes them fail by creating a short circuit in the windings.
I don't remember the wire size I used (it's been over 20 years) but you're right about the short circuit. Just one shorted turn will form the shorted secondary of a transformer, and the I^2R losses in that turn will create quite a bit of heat that will further damage the insulation on the nearby windings until the whole thing is toast.
Hi Phil, KA9Q
To prevent short circuits between turns of the windwing is suffice to use # 24 fiber glass copper insulated wire for class H insulation motors or transformers wich windstand constantly very high temperature around 180° C, Celsius i.e. 356 ° Fahrenheit.
I have used it with success in critical applications to rewind DC and AC motors working near steel melting fornaces for a Company in Italy 50% with the USS Steel in Pittsburgh Pennsylvania.
73" de
i8CVS Domenico
participants (9)
-
Bill Booth -
Clive Wallis -
David Palmer KB5WIA -
i8cvs -
Joe Fitzgerald -
Nick Pugh -
Phil Karn -
Tim Cunningham -
WA6FWF