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Posted 04 September 2010 - 07:26 AM
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Posted 24 December 2010 - 08:34 AM
Edited by videobruce, 24 December 2010 - 09:53 AM.
Posted 24 December 2010 - 09:46 AM
The obvious advantage is you use only one cable between the control box and the rotor. The control to turn the rotor is through the coaxial cable. They do warn you of two things;
1. They recommend pure copper center conductor rather than the more popular copper covered steel which is less expensive. If you do use the cheaper cable it has a limit of 75'. With the pure copper the limit is 200'.
2. You are restricted to what pre-amp you use. The limit is 50ma at 17vdc.
The specs are here (sold through Solid Signal among others);
Ok, now for the bad news. There is no free ride with this single cable deal as I suspected. Their specs claim a loss of only 1db per device (2db total). Well, at certain frequencies that is true, but there are a few exceptions.
My measurements with a Spectrum Analyzer show a loss of -4.5db around 780MHz (ch65). There are also losses between 3 & 4db around the following frequencies; 493 (ch 17), 601 (ch 35-36), 675 (ch 47-48) & 710 MHz (ch 53-54).
This doesn't include the loss for each fitting in and out of the rotor & control box (probably around another 2 db total).
BUT, there is a easy solution; Run a separate cable (or wire since you don't need to use another coaxial cable for a control signal) as you have done in the past and solder it to a 'F' fitting at either end and run your downlead as before. Done!
Ok, then what's the big deal?:
Any of the Channel Master clones imported from China are notoriously inaccuate especially if you 'rock' the rotor back and forth to 'tweak' the position of the antenna. No matter how many times you 'Zero' the rotor and control box out doing a full turn to 360 degrees and back to 0 degrees, it will never be acuate. Even with the solid state remote control box that Channel Master offers (9537), it doesn't help (much to my disappointment).
For the tests;
I ran the rotor in both directions. 52 seconds was the duration between 0 and 360 degrees. Unlike all other CM 'clones' this rotor will go to 450 degrees which means you don't have to go all the way around just to go from 10 degrees to 350 degrees. There is no 'north' stop.
I rocked the rotor back and forth a number of times and it stayed within spec which is 2 degrees of accuracy.
One thing I did notice was the readout of the control box was faster than the speed of the rotor. Doing a 0 to 360, the readout reached 360 long before the rotor did. It was repeatedly off by 45 degrees. IOW's the box said 360, but the rotor was only at 315. Same in going the other direction. When the box read 0, the rotor was at the 45 degree point.
Mind you, it didn't affect the final result. The rotor just keeps turning until it gets to where it should. I plan to contact the manufacture and inquire.
Current consumption was measured at .07 amps when in standby and .08A in the 'on' state. This is another device that is never 'off'. To me, even though it isn't much, to draw 5-6 watts when the device isn't doing anything is just poor design.
I measured .13 amp when the rotor was turning and under high stress (holding the rotor with both hands to try to stop it from turning) the load was.18 amp. The box does get slightly warm after a while, but it didn't seem excessive.
I contacted the company and they confirmed the timing difference (if you will) between the readout of the control box and the actual position of the rotor.
I brought up a perfect example of why this is bad. If you are hunting for the best 'spot' for a certain station and are doing a 0-360 (or vice a versa) and find a spot, when you take note of the readout, it will be incorrect as the readout doesn't track' with the rotor. He agreed and said he will bring that up with engineering.
It was never addressed.
Posted 24 December 2010 - 09:50 AM
I just discovered this a few weeks ago. I called their number and was told they were looking for another manufacture to produce these units since the two Chineese companies that supplied these raised prices, making them uncompetitive. As of now, no word on any new source yet. I hope they find someone since I still feel it's a decent buy in spite of the 'quirks'.
Having said that, I did run into a problem 2 years after I purchased my unit. To make a long story short, five of the six screws that hold the main motor/gear plate to the housing loosened and fell out inside the housing causing the circuit board on the motor and the main control board to short out. The rotor stopped responding. I ran some checks without removing the rotor and called the company. We came to the conclusion that it was the control board. I ordered a replacement for $18 (plus shipping). I also ordered a whole replacement rotor for $38 as a spare. When I received the order I removed the rotor and noticed something rattleing around inside. I had no idea what it was untill I removed the bottom plate. From all the recent windy days we have had in the past year or so, the constant rocking back and forth loosened those screws and all but one fell out. One 'cap' on the manin board completely broke off, but something else went south since replaceing that disn't solve the problem. I replaced the board with the new one, but the motor still didn't respond.
I called the company back and told them even though it was one year over the warrenty period I fealt I shouldn't have to take the 'hit' for this. He aggreed and sent me another rotor at no charge. I used the rotor I purchased to replace the orginal and now have a spare.
He admitted this has happened before. There was a black substance on the screw threads which was suppose to prevent this, but it seemed more like dried grease. I removed the screws on the replacement and used lock washers this time and tightened them down as best I could. I'm hoping that will do the trick.
I dissasembled the orginal rotor and I canm report all the gears are metal! The ball bearings are in a 'race' that prevents them from dropping out. Unlike the orginal Channel master design where only grease holds them in palvce (if your lucky), these can't fall out so you can't loose them. They are also twice the size of the CM design. The only reason one would have to remove that plate is to replace the motor itself since the screws that hold it in place are only accessible from inside. I can't see any way any of those gears would fail.
Thre was concern regarding the small motor. With the gear reduction, I really don't see a issue here. It's not lifting the antenna, it's just turning it. One note of caution, I don't know if I would use this rotor mounted upside down in an attic (hanging from the rafters) since the 'clip' that holds the main shaft in place isn't made to support all that weight. The CM design is somewhat better in this repsect.