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on March 21, 2009
I have now owned two of these units. When the first failed I purchased a second on the assumption that I must have had a weak one that glitched and that it would be easier to hook up the same unit. Like clock-work, or rather poorly made Chinese clock-work, the second unit has failed after only 1 1/2 years. We live in Maryland, a moderate climate with a medium size antenna on a short mast. The unit was not heavily used nor heavily stressed. After two failures in less than 4 years, I am convinced the Channel Master is not the brand it used to be and is now just another example of cheap Chinese junk packaged under a once venerable American brand name. Sad.

Jay S.
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on December 4, 2008
I have this Channelmaster model, which I installed about a year and a half ago. It received moderate use for a seven foot FM-only antenna. I found the accuracy to be good when given occassional resets.

Why the past tense? Well, about a month ago I started having serious problems with the 9521 motor unit: it was not responding properly to the remote commands (the motor unit wouldn't turn past about 200 degrees even when a higher rotation was specified through the controller).

First stop was back to the owners manual. The troubleshooting section in the latter is very thin (a half a page of rather general suggestions, the most annoying being one that says "if you rotator is working but not properly aligning the antenna, either realign the antenna on the mast or re-coordinate it through the remote control." The manual contains no information whatsoever on how to do the latter!!!) So I ended up googling to find general rotator troubleshooting support. That led to more helpful info that allowed me to bench test the motor unit, which turned out to have become defective .

So I then had to shop for a complete replacement of the 9521 rotator unit. In the process of doing that, I learned that while these used to be manufactured domestically (in Ohio) a few years ago ChannelMaster started sourcing them from China. So what?

Well, according the the rotator experts in the shortwave community, there have been ongoing quality control issues (similar to what I experienced) with the Chinese made 9521 motor units. In fact, so much so that the particular retailer I ended up buying from now extensively tests each one before putting them up for sale. So stand advised and if you buy one of these make sure you keep all warranty documentation!
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on October 14, 2007
The product is easy to install and operate, and it performs basically as advertised, but there are a few things to grumble about.

First, communication over the control cable is one-way, from the control box to the motor. That means that the controller doesn't really know where the antenna is pointing. Rather, it knows, or thinks it knows, how fast the antenna rotates and figures how long it should take to get to where you want it and then assumes that it got there. My experience is that if it is really pointed where the controller thinks it is and you command it to rotate 180 degrees in one continuous motion, it will go somewhere between 170 and 190 degrees or so, but if you use the UP and DOWN buttons to "tweak" the pointing for best reception, the allowance for acceleration is not all that great, and you can easily have the antenna pointing 20 degrees from where the controller thinks it is. Second, the errors accumulate: if it starts from an inaccurately known position, it will end up with even less accuracy.

There is a "resync" feature, which consists of commanding the motor to turn counterclockwise long enough to give confidence that it's reached the "zero-degree" stopping point. That gets things back to a known condition, but it takes about a minute every time you resync, which is a pain. It would be much handier if the display reflected an actual MEASUREMENT of the position rather than a dead-reckoning guess.

Nevertheless, the unit does its job, and I have had no problems with it. If it's a little off in pointing, you can always do a fine adjustment with the UP and DOWN buttons. Maybe I was expecting too much for the price paid.
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on January 17, 2009
I bought this Rotor after having 1 before, reading good reviews and thought I was getting 1 of the Best Antenna Rotors on the Market and bonus Infrared Remote to boot. Besides I had 1 since 1989 that lasted up until 2005.

I purchased new because I installed a HDTV Antenna and wanted to get All of the available over the Air Stations.

Well about a year later, the thing stops working and is stuck pointing due NORTH. I tried the owner install and troubleshoot manual but everyting tested OK. Then I called the Channel master Tech Support and he basically said that they have had major problems with the Gear sets sticking at the 0 deg or 360 deg position. All I had to do was fax him my original purchase receipt (which I can't find). I then asked if I could just give the serial # which should be in their database, to get replacement. He apologized and said that was not going to happen.

Sooo, Good luck to those of you who decide to purchase this model.

01/28/09 added comments: Price has jumped to $183 w/o shipping, for an item with only a 90 day warranty.

I just tried to repair my own Rotor and found Water & Rust throughout the inside, even though I was very careful to calk the outside parts. The only way for water to get in was thru the Rubber cover grommet. Very poor quality. I will never purchase another Channel Master product!
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on July 6, 2009
I just purchased the Channel Master 9521A last week. Based on people's experiences documented here and elsewhere, I had reservations, but was assured by others of the unit's overall good success in the field. I decided to bench test the unit prior to installation. Good thing I did! Read on... all is well that ends well.

Not understanding how the 'sync' function actually worked, the first thing I decided to try was performing a sync operation, first thing right out of the box after wiring everything up. The unit just sat there with the motor humming and nothing moving. Turns out that this behavior was consistent with the unit's design, since the rotator was already in the state expected when a sync operation ends, thus no more movement was possible. The controller is a simple timer based design and simply sends current to the motor based on a time interval (< 1 min.). The time the controller attempts to activate the motor is sufficient to cause a full rotation back to 0 degrees, assuming everything is operating as expected.

The next test was to try the up/down arrow buttons on the controller remote to make the unit rotate manually. Unfortunately, it only rotated about 1/2 way around before reaching a point where it wouldn't turn any further, either forward or backward. It was stuck! I could here the motor being energized (hummmmm), but no movement was happening.

I am the tinkering type, so I decided to take the unit apart and see what the problem was and determine if I could fix it. For me, this was a preferable option vs. going down the path of return/repurchase. The disassembly started with removing the bottom cover and then removing the 5 Allen screws holding the motor/gear assembly to the housing. The rubber boot that surrounds the base of the upper mast had to be removed in order to allow the inner works to be removed from the housing. Everything on the inside of the box slips right out as one complete unit. Once I had it apart, I hooked the wires back up and conducted the bench tests all over again. Everything worked like a champ! Ran all kinds of tests, sync, manually movements, up/down adjustments, etc., everything just worked, which led me to conclude that something with the housing was 'binding' up the works.

In my final analysis, there is a total lack of lubrication where the rubber boot providing the weatherproofing makes contact with the housing. I applied a very thin layer of high quality grease to all the surfaces where the rubber boot that makes contact with the housing. I also put a light coating of grease on the main shaft where it just might contact the housing - though this contact is unlikely. I put it all back together and started to run the tests again.

Viola! Everything works as designed. Now that I understand what I've got and how it works, I have complete confidence that I can install the unit as planned.

I realize my approach isn't for everybody, but I hope my experience will help others in their decision making process.
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on June 5, 2015
This rotator is better than some of the other light duty items out there BUT it still leaves much to be desired.

PROS: Uses all metal gear drive train.
Non volatile memory in the controller
Decently constructed (considering the price point)

CONS: No azimuth direction feedback... the controller guesses antenna position (none of the cheaper models offer azimuth feedback).
Uses spring lock wire connectors (like those used on cheap stereo speakers and stereo components)
Gear train alignment could be better. My unit has an audible misalignment when bench testing.

First things first... DO NOT mount this unit up on your roof or tower without testing it thoroughly. I tested mine on my bench first. I then mounted my unit on a 10 foot pole strapped to a deck post with the antenna on it and used it that way for 2 weeks. So far so good.

The wires attach to the rotor and to the control unit via spring clip wire retainers which are the same type you will find on lower end audio receivers and speakers. For me, this method of connecting the "outside" wires is unacceptable. So, on the rotor, I removed the spring clip assembly and added studs for the connections (see attached picture). The picture showing the rear of the controller unit shows the spring clip assembly which is used on both units as shipped from the factory. I understand that making this modification voids my warranty but there was NO WAY I was going to mount this rotor 30 feet in the air with nothing more than a spring clip holding the wires on. Harsh weather would eventually cause corrosion rendering the rotor useless.

The control unit has nice features which other reviewers have noted and can also be seen in the manual. It is much smaller than I had expected and it uses a "wall wart" to supply the needed 18VAC required to run the controller and the rotor. You will need to purchase the appropriate length of three conductor cable to attach the control unit to rotor. Since the control unit does NOT know the actual azimuth location of the antenna, occasional re-syncing of the two units is necessary. Re-syncing is not too terribly difficult but is somewhat time consuming as the rotor unit only turns at 1 rpm. The re-syncing process could take up to 2 or 3 minutes in a worse case scenario.

All in all the unit is not bad considering the price point. A unit that will "tell" you the antennas actual azimuth will cost upwards of $250 and probably much more. I do not turn my antenna all that often so for me this unit will do the job nicely. Many of the other units sold do not have a all steel gear train and I am sure that those units will not survive the harsh Michigan winters.
review image review image
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on March 3, 2009
I bought my first 9521A in 2001. Then in 2006 I had to replace both the rotor (Frozen) & the controller (Blank Screen). Now it is 2009 and the 2nd rotor is frozen in the North Position! Maybe you should give discounts on bulk ordering!
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on January 17, 2009
I have this Channelmaster Rotor with Remote, which I installed about a year ago. I used it for more HDTV Channel reception.

Why the past tense? Well, about 6 months ago I started having serious problems with the 9521 motor unit: it was not responding to the remote commands (the motor unit wouldn't turn from due North 0 or 360 degrees

First I referred to the owners manual. The troubleshooting section in the latter is very thin and basically said to replace the Rotator Unit. So I ended up googling to find general rotator troubleshooting support. That led to more helpful info that allowed me to bench test the motor unit, which turned out to have become defective (Stuck).

So I emailed Channel Master for more Support for the 9521 rotator unit. The Support Tech was helpful but said that this is a common problem and he would replace it if I could produce the original receipt, which of course I could Not! My problem with this type of Warranty, is that they know when it was manufactured by the Serial # I gave them & they know it has been on my Roof Mast only. So, why not ship new one to me & I ship junk back with RMA#. They already admit to problem. He did suggest buying a Ham Radio Mast Rotor, but cheapest is about $350~500. Now way.

So be advised and if you buy one of these make sure you keep all warranty documentation and Receipts!
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on July 28, 2012
This took place during 2006-2007 - With the changeover from analog TV signals to the new digital format, I was forced to erect an OTA tower/Antenna installation in order to receive the signals clearly. My father-in-law had several sections of a tower (style is the Amerite Series 25), he no longer needed, that totaled about 53'. My intention was to mount the CM 8-bay antenna, pre-amp, and CM rotor; connect all the necessary wires and RG7 coax (distance was 150 ft from tv) to the tower, then raise it up and drop 4' of the tower straight into the ground; using six 3/8" cables to anchor it and, hopefully, keep it from toppling during any hurricanes we encounter here in the FL panhandle. Went up as planned! Still standing today. I chose CM for the rotor because my uncle had one that lasted more than 25 years and I trusted the quality and workmanship. I did test it while on the ground and it seemed to work fine. Well, it was working great for the first three months; then it stopped rotating. The antenna is permanently facing south, which happens to be pointing straight out into the direction of the Gulf of Mexico, while the antenna farm is east-north-east of here! Needless to say, I wasn't real happy with the CM rotor at that point and since I'm not a pole climber and can't really afford to rent a cherry picker; the antenna just sits atop of the tower as a perch for birds!! If you can get a hold of the old CM Color Master rotor, the one made in the US, it will probably work fine; but the newer crap from China --- STAY AWAY FROM THE CM ROTOR!!!
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on July 11, 2013
I am a very experienced electronic engineer and bought this for a TV antenna. It has been up for only 2 years and I rotated the antenna perhaps 8 times in 2 years. It stopped working this week. I temporarily put a new short power cable on the rotor to the controller just a few feet away so I could see whether the cable was the problem. It was not. I reset the control box per the instruction manual and all indications are that it is working correctly. But there is no rotation and I do not feel or hear anything from the rotor motor. I phone Channel Master in Arizona and was transferred to "Technical Support" a man named Steven. I asked him i he could tell me the voltages I should see when I measure between the 3 wires. He said he did not have that information. I asked if he could provide a schematic diagram and he told me that all he had was the same minimal installation sheet that came with the unit and is on their webpage. He said that he had no ability to get the schematic or any other technical information. This is truly useless for "Technical Support".

Do not buy this product. It is junk and will not last and you will only be told to replace it with another when it breaks.
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