yeap, the point of the test would be to see if that the little wallwart power supply that comes with the newer ones just doesn't have enough "onions" to drive the motor when it's cold out. Got a multimeter there?
Edit: 795 mA AC from the same terminal, 12 deg F.

Of course MT, it’s not a voltage issue but an amperage available issue! The test should be how much does the voltage drop during start up on either set up 18 or 30. What would be acceptable 20% 30%? Higher voltage used (30) on an 18 v unit will compensate a bit for the drop. Once the motor is at speed the voltage will be too much. The real solution may be 18v power supply with higher available output (onions) say 2A instead of 1.

We seem to be converging on the root cause. A Power supply with insufficient current capability to start the motor at low temperatures. One way to test this hypothesis would be to parallel the outputs of two identical power supplies and see if it overcomes the freezing issue. If you try this, make sure that you get the polarities right. Otherwise, you risk burning out both power supplies.

A partial solution would be to go to a larger wire, especially for long runs, to reduce the resistance of the control wire and make more of the scarce power supply current available for the motor.

If the capability of the power supply is indeed the problem, how do we get Channel Master to fix it? And what about complaining to the retailer? Does Save'N Replay know about this? They sold me my unit.

Does anyone have two identical 18V power supplies that they could parallel to test this out. It is a heck of a lot safer for the motor than exposing it to a voltage of 1.7 times the motor rating (30 V on a 18 V motor). High voltage would work for a limited period of time but would damage (destroy?) the motor over time. And a rotor motor that is 50 feet up in the air is not readily replaced.

I don't have a frozen one to test with, but some basic math tells the story.

The old one I have, is capable of 30 VAC @ 1 A or 30 VA (~ 30 Watts if we ignore power factor for a moment). Compared to the new one u guys have, 18 VAC @ 1A or 18 VA (~ 18 watts).

The temperature issue is two fold the way I see it.
a.) Any motor large or small will have less efficiency at cold temperatures compared to their efficiency at Normal Operating temperatures.
b.) The mech. drag is increased in the cold (from the Grease, etc.)

Small AC motors have very low efficiency to begin with, relative to say a motor used in ur washing machine or sumthin. Power consumption just isn't normally a design constraint for a small motor. So neither is efficiency.
If it were me, I would just try and find something middle of the road, that used a larger wall wart, like from an old DSL Modem or sumthin, that ran on 24 VAC / 1A for ~24 watts and put the proper connector on the end, and try that to see if it helped.
And as someone else already mentioned, I'd probly be more concerned with the increased power dissipation of any internal voltage regulator of the control box itself, than hurting the motor. If ya used a higher voltage in to the control Box, Power Dissipated by any Voltage regulator is (Vin - Vout) x Load Current, since Vin ^^^ so would the Pwr dissipated by the regulator. That's why I'd say meet it half way for a quick test...

We seem to be converging on the root cause. A Power supply with insufficient current capability to start the motor at low temperatures. One way to test this hypothesis would be to parallel the outputs of two identical power supplies and see if it overcomes the freezing issue. If you try this, make sure that you get the polarities right. Otherwise, you risk burning out both power supplies.

A partial solution would be to go to a larger wire, especially for long runs, to reduce the resistance of the control wire and make more of the scarce power supply current available for the motor.

If the capability of the power supply is indeed the problem, how do we get Channel Master to fix it? And what about complaining to the retailer? Does Save'N Replay know about this? They sold me my unit.

Does anyone have two identical 18V power supplies that they could parallel to test this out. It is a heck of a lot safer for the motor than exposing it to a voltage of 1.7 times the motor rating (30 V on a 18 V motor). High voltage would work for a limited period of time but would damage (destroy?) the motor over time. And a rotor motor that is 50 feet up in the air is not readily replaced.
Putting 30V on an 18V motor isn't necessarily a problem, in fact, we don't know the maximum current the motor can handle. All we know is that some control boxes output 30VAC, while others output 18VAC. 300sflyer's resistance measurements of the coils suggest that the motors are largely similar.

If you're still concerned, what can be done is to put a pot in series with the motor coils, one for each coil, and a 30V control box or transformer used. The pots can be adjusted, slowly incrementing the current going to the coils until the motor moves in cold weather. The pots must be high wattage, enough to handle the full current that the motors will see.

I'd agree with the larger conductor wire though, when I put up a 80' tower just over a year ago, I used 16ga extension cord wire. It works well, never freezing up in the winter.
I believe it was a 30VAC control box.

I'd agree with the larger conductor wire though. . . .

I agree. Replaced the Channel Master 22 gauge wire (80 feet) with Radio Shack 20 gauge wire & my reliability issues disappeared. Can't compare the temperatures we get here with those in Canada, but the unit works fine down to at least 10°F here.

Major T is right you just can pump more juice thru the control unit. Direct feed to the motor for testing?

This torque can be increased by increasing the drive voltage. The only limitation to this is that the motor windings use a certain conductor size, which limits how much current that they can safely handle.

It is actually the current through the windings that affects the torque (the strength of the magnetic field is proportional to the current through the winding). While Ohms law states that voltage and current are proportional, there is a voltage drop in the wires between the controller and the rotor. As a result it would be optimal for the controller to have a constant current source, but it is likely that most have a constant voltage source since it is cheaper and easier.

Indeed, torque is proportional to current, however given the fixed resistance of the motor and the installed wires, the drive voltage must be increased.

A constant current source will achieve the same result: voltage at the terminals of the motor will be higher. The constant current source, with enough voltage headroom, will just give you a constant current regardless of the load resistance.

Ivan

My CM rotor is still working just fine. The increase from 18V to 30V using the older CM contoller, has had no ill effects thus far. :)

Hi All:

I'm about to put an antenna (old-style CM4228) and rotator (Alliance T-45) outside on the chimney and had some quick questions:

1 - My current 5-conductor rotor cable running up to the attic will be too short for the longer (50-foot) run to the chimney, so I'll need to replace it. Since 5-conductor rotor cable apparently isn't available, I've read that a good substitute is 18-5 thermostat wire or underground sprinkler system wire. Would it matter if the 18-5 wire were solid instead of stranded like my current rotor cable? Also wondering whether the "UV-resistant polyethylene" or "long life PVC" outer jacket is preferred. Thought I'd check Home Depot or Lowe's locally for a 50-foot spool of one of these.

2 - Since we get a lot of wind here, and the CM4228's screen is like a big sail, I thought I'd add a support bearing. I've seen NTE's TB-105 support bearing online, but some reports say it's too big for a 1.25" mast. Wondering if these reports are exaggerated, whether any other bearings are available, or whether I should try something like this:
http://www.ad5x.com/images/Articles/TB105.pdf

Thanks in advance for your comments.

Sprinkler system wire works just fine. Solid cable won't make a difference. In fact, it likely provides better performance over longer runs.

And I generally recommend a wire that offers improved UV resistance. Either way, it's always best to route cables in a manner that keeps them out of the sun as much as possible (i.e. along north-facing surfaces).

gcd0865 a thrust (support) bearing is well worth the trouble of locating one, so keep checking for other suppliers to get the size right.

My dad had antenna and rotor removed from his roof when he had the roof redone.. This antenna was there when he bought the house but no controller box. The rotor is not marked but after a little research, I think its a U-100 or U-110.. Seeing we dont have the control box, is there anyway to test the rotor to make sure its good, before we purchase a controller box.. The house as built in the early 80s we think..
I uploaded a few pictures here
http://flic.kr/p/9tzsaQ
http://flic.kr/p/9twuDP
http://flic.kr/p/9tzris

Also, should we be able to turn any of this or any movement when its not hooked up to power..We had the case cracked open, but it didnt seem that any of the gears would move by hand..

Seeing we dont have the control box, is there anyway to test the rotor to make sure its good, before we purchase a controller box.
Looking at the pictures of the gears, they seem to be in excellent shape. Theres some rust on the transformer core, but thats normal. Just make sure the wire connections on the inside are good. A little dab of waterproof high temp grease on the gears looks like all it needs. Dont use a lot grease, just apply on the teeth of the gears.
You really need a control box to test it out properly. You should be able to get a control box for it at a flea market or on ebay cheap. The only problem with the control boxes, due to age, is that the non polarized electrolytic capacitor inside is dried up. If its never been replaced, it can be replaced with two normal electrolytic capacitors negative to negative back to back.

Also, should we be able to turn any of this or any movement when its not hooked up to power..We had the case cracked open, but it didnt seem that any of the gears would move by hand..
Yep, it should be very hard to move by hand. Sometimes with antenna mast inserted for leverage, you can move it. Its made that way so the wind wont move the antenna.
But sometimes with a big antenna and big wind, it will move.

BTW, the motor that they use inside of it is the same motor used for phono turn tables in the 50's and 60's, 70's, heh.

Thanks 300.. I think I found a u-110 box to buy.. I will send my nephew to go get it this week.. I hate living in a small town sometimes:mad:

Also.. I have a grease gun filled with a greenish blue grease that is used to industrial motor bearings and hanger bearings.. I used to work in a grain elevator and grabbed some grease before I quit LOL.. Do you think this will be fine to use?

Hello

When I moved into my current house, the previous owners already installed an antenna on a tower. For some reason I never really made use of it until now. I am slowly getting into it but the results have not been great. I am only able to receive four digital channels( CBC, CTV, The CW and a french channel) Of these four only CBC and CW have the strongest signal while CTV is the weakest. I am in Scarborough and the antenna is currently pointing in an westerly direction.

The antenna is connected to a rotor but I do not have a control unit. From what I remember, the control unit was an older style where you turn a dial to control the antenna. I no longer have this unit available. The cable running from the rotor is a thin flat cable with three leads. Is there a universal control unit that would work with this type of wire?

I have provided a picture of the rotor and cable

http://img215.imageshack.us/img215/8052/mickey002.jpg (http://img215.imageshack.us/i/mickey002.jpg/)

http://img51.imageshack.us/img51/5008/mickey005.jpg (http://img51.imageshack.us/i/mickey005.jpg/)

Unfortunately, the rotor is too high for me to get a better look

Any help would be greatly appreciated.

We'll help you with the rotor situation here as best we can. :)

In regards to Scarborough reception you can see in the following thread that you should be getting more digital stations than that, even with bad aim, so clearly there are other problems with your inherited OTA gear. We'll discuss those reception matters here:

ON - Scarborough, Pickering, Ajax, Whitby, Oshawa - OTA (http://www.digitalhome.ca/forum/showthread.php?t=36538)

As for the 3 wires, hopefully you can borrow a controller box (any typical 3-wire brand that is NOT 30V) in order to test. The reason you don't want one of the high voltage boxes is that the rotor might be an 18V unit that could be old enough to fry with too much juice. OTOH testing a 30V rotor with an 18V box is safe and should at least show some movement to indicate whether the rotor is seized or not.

Hooking up the 3 wires might require some trial and error to get the polarities correct.

Thanks for the advice Stampeder. I may be able to get my hands on an old CM control unit to test out.

As for the other problems, that may well be true. I hooked up the antenna to my tv a couple years ago just to test it out and I was able to pull in 9 or so digital channels at that time. Unfortunately, I do not recall if the direction of the antenna has moved since then.