Hi all rotor experts.

Seems like my CM 9521A is drifting away from preset saved channels. It happens fairly slowly usually but I guess it depends on the wind speed and direction. By 'slowly', I mean it will be OK today, then tomorrow evening, I'll have to tweak the preset locations a little. Sometimes its a couple of degrees, other times it has been 10-15 degrees. Is there a quick way repoint?

The description on S&R's website states:
"Automatic Synchronization Ensures Pinpoint Position Accuracy"
How does this work? Can someone please explain how to do this properly?

Thanks,

Larry

@gohabsgo2: I believe earlier in this thread are posts which describe similar issues with the Channel Master rotor--my understanding this is a common issue for them.

The issue could be exacerbated by excessive load and/or too long of a mast on the rotor. How much mast and load (weight and wind) do you have on your rotor?

Seems like my CM 9521A is drifting away from preset saved channels. Is there a quick way repoint?

The description on S&R's website states:
"Automatic Synchronization Ensures Pinpoint Position Accuracy"
How does this work? Can someone please explain how to do this properly?

Thanks,

Larry

Hi Larry:

The CM 9521A (along with other brands) uses timing only to set your rotor position. The controller does not know exactly where the rotor is pointing as there is no feedback from the rotor to tell the controller its direction.

The auto synchronization (from the manual) appears to be hands free method to re-point the rotor and controller back to the same direction. Eg The controller rotates the rotor clockwise to the north position and then counter clockwise to the north again. If the rotor and controller were out of sync, this action will get them back together inidcating the same direction. For example. If the rotor was facing west, and the controller was indicating south, rotating the controller to the north (thru the west position - clockwise) the rotor will stop in the north position by the mechanical stops in the rotor. The controller will continue to rotate until it indicates north. If the rotor and controller were pointing incorrectly in the other direction (controller south and rotor east) rotating counter clockwise will correct for this error.
It appears that the auto synch performs this operation after about 50 programmed moves. The manual says it does a counter clockwise movement, but I think a clockwise rotation is also needed.

No there is no quick way to re-point.

Hope this explains it.

There are essentially two means of keeping accurate direction control between a rotor and the control box. Most rotors employ one of these:

1) Electromechanical sync. Both the rotor and control box have a motor and gear that turn at the same ratio when energized. As the two are energized simultaneously, in theory they should both maintain the same level of rotation.

2) Potentiometer (http://en.wikipedia.org/wiki/Potentiometer). This device, located in the rotor housing, determines the position of the rotor relative to the far clockwise (or counter-clockwise; depending on the brand) position. This information--typically communicated by voltage level--is sent back to the control box.

The Channel Master rotor uses option 1 above. Better rotor systems use option 2.

So,
Anyone know if the CM 9521A rotor is capable of taking a lighting strike? The strike destroyed my CM7775 preamp power supply as well.

With the preamp, getting a new power supply fixed that... I am getting channels in nice and strong. (Stronger than ever actually oddly enough.) But I purchased a new CM rotor controller wired it up and the rotor does not move anymore.

Could it be a dead rotor? I would think they are engineered to take lighting hits as they are essentially lighting rods.

I guess the hit could have popped the wires out up there too? (My phone line was knocked out too.. the Bell tech said the wire had been blown right off the demarcation box from strength of the power strike.)

Any thoughts before I get someone to come look at it? (I'm not climbing a 40 ladder to reach the bottom of the mast...)

Thanks.

There are essentially two means of keeping accurate direction control between a rotor and the control box. Most rotors employ one of these:



2) Potentiometer (http://en.wikipedia.org/wiki/Potentiometer). This device, located in the rotor housing, determines the position of the rotor relative to the far clockwise (or counter-clockwise; depending on the brand) position. This information--typically communicated by voltage level--is sent back to the control box.

The Channel Master rotor uses option 1 above. Better rotor systems use option 2.

Out of curiousity what common rotors use a potentiometer for rotation location? Just wondering since I am likely in the market for a replacement rotor.

Hi all rotor experts.

Seems like my CM 9521A is drifting away from preset saved channels. It happens fairly slowly usually but I guess it depends on the wind speed and direction. By 'slowly', I mean it will be OK today, then tomorrow evening, I'll have to tweak the preset locations a little. Sometimes its a couple of degrees, other times it has been 10-15 degrees. Is there a quick way repoint?

The description on S&R's website states:
"Automatic Synchronization Ensures Pinpoint Position Accuracy"
How does this work? Can someone please explain how to do this properly?

Thanks,

Larry
1) Press the far left button on your controller and the antenna will resync. Wait for this to finish (a few minutes).
2) Peak your antenna aim to maximize reception.
3) Resync the antenna.
4) Check you are still set to maximimize reception. Fine tune the aim if required.
5) Resync one more time if you moved the antenna at all in step 4.

The above steps will get your antenna dialed in pretty well. Whenever you find aim is off, them simply hit resync again to automatically dial the antenna back to where you want it to be.

I repeat syncing a few time as there are some that say rocking your rotor back and forth a few times to peak the aim is not very accurate. For example, while your display may say it moved 4 degrees, it may have only moved 3 degrees... do movements back and forth several times and you can compound the error quite a bit.

Lightning tends to melt parts, such as the cabling or other electrical connections. Or fry motors...

Rotors with Potentiometers: Hy-Gain's AR-40 and 45, HAM4, etc. I believe the Yaesu rotors also have them.

Yes, the Yaesu rotors have a potentiometer.

So,
Anyone know if the CM 9521A rotor is capable of taking a lighting strike?

I would think they are engineered to take lighting hits as they are essentially lighting rods.

.
There is no lightning protection built into the rotor or amp… believe it or not.
You need to install lightning arrestors on the coax and rotor control cable right where it enters your home. The fact that it got to the power supple tells me you don’t have any lightning protection in place.

The motor is cooked and will have to be replaced. A lightning arrestor would have provided a low impedance path to ground off the charge, not having that the charge found its way into the motors windings and melted it open just like what happened to your phone wire.

There is no lightning protection built into the rotor or amp… believe it or not.
You need to install lightning arrestors on the coax and rotor control cable right where it enters your home. The fact that it got to the power supple tells me you don’t have any lightning protection in place.

The motor is cooked and will have to be replaced. A lightning arrestor would have provided a low impedance path to ground off the charge, not having that the charge found its way into the motors windings and melted it open just like what happened to your phone wire.
No, actually everything was properly grounded thanks. Despite a direct strike to my house I had minimal OTA equipment damage. (I know it was a direct strike as sparks were literally falling off the side of the house. It was quite the bang and visual spark show.) Outside of an apparently blown rotor and blown pre-amp power supply nothing else was damaged. My two HDHomeRun tuners are perfectly fine. My coax cable is fine. My MythTV box is fine. My ground wires are intact.

I did get damaged computer equipment (blown network ports and network switches - the computers still run fine otherwise.) The insurance adjuster said it is common for networking equipment to get fried even if the strike is 500M from your house. So you know what? I'm pretty comfortable that the correct grounding of my OTA setup did its job perfectly fine thank you very much.

Rotors with Potentiometers: Hy-Gain's AR-40 and 45, HAM4, etc. I believe the Yaesu rotors also have them.
Thanks. Though correct me if I'm wrong... but the potentiometer ones seem to start at around $350 and up? Or is there anything else that is less expensive? Seems like a pretty expensive upgrade over a basic CM rotor.
What other benefits over accuracy of the aim do they have? Just trying to understand the value proposition of the more expensive rotors.

Anyone know if the CM 9521A rotor is capable of taking a lighting strike?I know some hams who run a 6AWG or 8AWG copper bypass jumper from the antenna mast to the tower below the rotor, leaving enough room for full rotation of the antenna(s). Its the same idea as a ground jumper around a water meter.

You can buy perfect cables for this purpose in the car battery section of any auto parts store in a variety of lengths.

It might seem like overkill, but if it increases your comfort level and hopefully prevents or at least reduces any interior arcing in the rotor or down the controller wires I'm all for it, especially for the really expensive rotors! ;)

As always, I remind everyone of our Grounding Info & Standards: OTA/Dish/CATV/Telecom thread, (http://www.digitalhome.ca/forum/showthread.php?t=62265) which contains a huge amount of information on the subject.
(http://www.digitalhome.ca/forum/showthread.php?t=62265)

I always wondered if running a wire from the antenna mast (above the rotor) to the main mast made sense to do. I was unsure how the upper section would handle a strike... since the only "ground" wires down are the coax and the rotor controller wires.

Hi guys. Have just bought a 9537 controller to replace the old 9510. New one does not work. 9537 has 3 wire on back 1 = green 2 = black and 3 = red. the old control has 123 but are hooked up the other way around. This one has been hooked up for at least 7 years, so should be OK. If I assume that the wires on the motor are hooked up wrongly also, will I blow something if I go to 1=red on the new controller. thanks Taffy

No, it will jsut go backwards.

match

1 to 1
2 to 2
3 to 3

I always wondered if running a wire from the antenna mast (above the rotor) to the main mast made sense to do. I was unsure how the upper section would handle a strike... since the only "ground" wires down are the coax and the rotor controller wires.
The antenna and mast are conductors.

@zounder1: When it comes to anything (including rotors), you get what you pay for.

I started off with an AR-40 (which I love), but recently upgraded to a HAM4. The HAM4 has a better control box (I like the degree indicator better, and I plan to integrate it with a control connected to my PC), exceptional turning and braking power, and durability. Hy-Gain also sells every part for these rotors. Unlike Channel Master, where acquiring parts can be difficult.

You can pay around $150 for something that will last a few years with irritating issues like "drift", or $500-700 for something that will last a lifetime of trouble-free service.

These more expensive rotors can also take lightning hits better. I've got friends (HAM operators) who've used the HAM4 rotors for decades--having taken many hits over the years--and still work flawlessly.

You should always double check your connections before energizing--you can damage your equipment by powering up with incorrect connections.