Aligning a Rotator
Aligning a Rotator
Hi Satellite Finder Brains Trust,
I'm refurbishing myAz/El rotators for my 2/70/23 sat yagis and am interested in wether it is the norm to set the rotator to magnetic or true north. So if OrbiSatfinderPlus gives me a bearing is it True or Magnetic ? I appreciate there are a number of Norths that are possible but I am just looking for the convention rather than the most exquisit response.
Compton
VK2HRX
I'm refurbishing myAz/El rotators for my 2/70/23 sat yagis and am interested in wether it is the norm to set the rotator to magnetic or true north. So if OrbiSatfinderPlus gives me a bearing is it True or Magnetic ? I appreciate there are a number of Norths that are possible but I am just looking for the convention rather than the most exquisit response.
Compton
VK2HRX
Compton
VK2HRX
QF56ne, Ryde, Sydney
VK2HRX
QF56ne, Ryde, Sydney
Re: Aligning a Rotator
All I can offer is the benefit of practical and operational experience...
I have all of my satellite antennas aligned to magnetic north by use of a GPS. This includes my 2395Mhz dish which must track within 3 degrees of the ISS or you get no signal. I consistently obtain excellent results with all of my satellite antennas.
In answer to your question - Magnetic North.
Regards
Shane VK4KHZ
I have all of my satellite antennas aligned to magnetic north by use of a GPS. This includes my 2395Mhz dish which must track within 3 degrees of the ISS or you get no signal. I consistently obtain excellent results with all of my satellite antennas.
In answer to your question - Magnetic North.
Regards
Shane VK4KHZ
Re: Aligning a Rotator
Hi Crompton,
A little from left field - I align my az and el rotators to the sun or moon. If your tracking software has an option to track the moon then set it tracking the moon and adjust the poles in the rotators so your antenna's point to the moon.
Hope that helps.
Jayson
VK1JA
A little from left field - I align my az and el rotators to the sun or moon. If your tracking software has an option to track the moon then set it tracking the moon and adjust the poles in the rotators so your antenna's point to the moon.
Hope that helps.
Jayson
VK1JA
Re: Aligning a Rotator
Saves using a compass I guess. Just have to work out how to get me, a spanner and the moon up the ladder on the mast all at the same time.VK1JA wrote:Hi Crompton,
A little from left field - I align my az and el rotators to the sun or moon. If your tracking software has an option to track the moon then set it tracking the moon and adjust the poles in the rotators so your antenna's point to the moon.
Hope that helps.
Jayson
VK1JA
Good suggestion though, I'll investigate further.
Compton
VK2HRX
QF56ne, Ryde, Sydney
VK2HRX
QF56ne, Ryde, Sydney
Re: Aligning a Rotator
Hi Compton,
To keep the answer short, the software will be referencing True North.
For a bit more of an explanation:
Magnetic north is variable depending where you are located on the surface of the Earth - it is simply the direction that a magnetic compass will align. The earths magnetic field is not uniform. Most maps will indicate the number of degrees that magnetic is from True for the area that they cover (called "declination" or "magnetic variation"). In Sydney it is presently +12.57 degrees, meaning that your compass will indicate approximately 12.5 degrees east of True North.
Basically, if I take a magnetic bearing on a station in VK4, his bearing to me won't be exactly 180 degrees from my reading because his magnetic variation will be different to mine - our compasses don't indicate the same direction for north.
It is best to reference True North if possible. That way we are all using the same point of reference.
Regards,
Dave, VK2NR.
To keep the answer short, the software will be referencing True North.
For a bit more of an explanation:
Magnetic north is variable depending where you are located on the surface of the Earth - it is simply the direction that a magnetic compass will align. The earths magnetic field is not uniform. Most maps will indicate the number of degrees that magnetic is from True for the area that they cover (called "declination" or "magnetic variation"). In Sydney it is presently +12.57 degrees, meaning that your compass will indicate approximately 12.5 degrees east of True North.
Basically, if I take a magnetic bearing on a station in VK4, his bearing to me won't be exactly 180 degrees from my reading because his magnetic variation will be different to mine - our compasses don't indicate the same direction for north.
It is best to reference True North if possible. That way we are all using the same point of reference.
Regards,
Dave, VK2NR.
Re: Aligning a Rotator
Thanks Dave. I understand what Mag N is and how it is derived etc. So currenlty I have 1 vote for True, 1 for Mag and 1 for the Moon. Hmmm......VK2NR wrote:Hi Compton,
To keep the answer short, the software will be referencing True North.
For a bit more of an explanation:
Magnetic north is variable depending where you are located on the surface of the Earth - it is simply the direction that a magnetic compass will align. The earths magnetic field is not uniform. Most maps will indicate the number of degrees that magnetic is from True for the area that they cover (called "declination" or "magnetic variation"). In Sydney it is presently +12.57 degrees, meaning that your compass will indicate approximately 12.5 degrees east of True North.
Basically, if I take a magnetic bearing on a station in VK4, his bearing to me won't be exactly 180 degrees from my reading because his magnetic variation will be different to mine - our compasses don't indicate the same direction for north.
It is best to reference True North if possible. That way we are all using the same point of reference.
Regards,
Dave, VK2NR.
Compton
VK2HRX
QF56ne, Ryde, Sydney
VK2HRX
QF56ne, Ryde, Sydney
Re: Aligning a Rotator
THIS!!!
Because I don't have any obvious geographical features at true north or south, I improvised. I worked out the bearing of the side of my house in relation to true north from the Logger Mapping feature, set the rotator controller to that bearing, then pointed the antenna in the correct direction when tightening everything up. Elevation is simple
Calibration of rotators is a WHOLE different ballgame. My Yaesu rotator is crap. I have an old Alliance az rotator that needs a bit of a reno, but when last working, maintained 0.5deg accuracy right around the dial. The Yaesu is not as accurate
Once set, it's easy to do a boresite check on your pointing accuracy with the moon. Using the sun hurts, and may lead to premature vision loss.
Using the moon or sun obviously requires ensuring that your location data is as accurate as possible.
Why anybody would use magnetic north as a reference is beyond me. Almost all maps and software reference TRUE north.
And then this should be spot on:VK2NR wrote:Hi Compton,
To keep the answer short, the software will be referencing True North.
For a bit more of an explanation:
Magnetic north is variable depending where you are located on the surface of the Earth - it is simply the direction that a magnetic compass will align. The earths magnetic field is not uniform. Most maps will indicate the number of degrees that magnetic is from True for the area that they cover (called "declination" or "magnetic variation"). In Sydney it is presently +12.57 degrees, meaning that your compass will indicate approximately 12.5 degrees east of True North.
Basically, if I take a magnetic bearing on a station in VK4, his bearing to me won't be exactly 180 degrees from my reading because his magnetic variation will be different to mine - our compasses don't indicate the same direction for north.
It is best to reference True North if possible. That way we are all using the same point of reference.
Regards,
Dave, VK2NR.
VK1JA wrote:Hi Crompton,
A little from left field - I align my az and el rotators to the sun or moon. If your tracking software has an option to track the moon then set it tracking the moon and adjust the poles in the rotators so your antenna's point to the moon.
Hope that helps.
Jayson
VK1JA
Because I don't have any obvious geographical features at true north or south, I improvised. I worked out the bearing of the side of my house in relation to true north from the Logger Mapping feature, set the rotator controller to that bearing, then pointed the antenna in the correct direction when tightening everything up. Elevation is simple
Calibration of rotators is a WHOLE different ballgame. My Yaesu rotator is crap. I have an old Alliance az rotator that needs a bit of a reno, but when last working, maintained 0.5deg accuracy right around the dial. The Yaesu is not as accurate
Once set, it's easy to do a boresite check on your pointing accuracy with the moon. Using the sun hurts, and may lead to premature vision loss.
Using the moon or sun obviously requires ensuring that your location data is as accurate as possible.
Why anybody would use magnetic north as a reference is beyond me. Almost all maps and software reference TRUE north.
Alan VK3DXE
QF21nv
QF21nv
Re: Aligning a Rotator
Whilst in some places magnetic and true north are close it's certainly not the case in NSW where you are.
Choose true north.
Choose true north.
Lou - VK3ALB
Being right doesn't excuse bad behaviour
Being right doesn't excuse bad behaviour
Re: Aligning a Rotator
How it was explained to me when I initially set up the tracking software with the AZ/EL rotators is the antennas should be aligned to magnetic north and once your longitude and latitude is input into the tracking software any required correction is made. All of my antennas were set up using this method and they work. I have three of the Yaesu AZ/EL rotators and yes they can be difficult to calibrate - all three behaved differently during the calibration process.
Crompton, I apologise if I have confused the situation but this was not intentional I only offered my comments based on how I set up my satellite tracking antennas and it worked for me.
Crompton, I apologise if I have confused the situation but this was not intentional I only offered my comments based on how I set up my satellite tracking antennas and it worked for me.
Re: Aligning a Rotator
Got it, line them up to mag north on the mast and then account for the mag to true variation in the controller. Makes sense.VK4KHZ wrote:How it was explained to me when I initially set up the tracking software with the AZ/EL rotators is the antennas should be aligned to magnetic north and once your longitude and latitude is input into the tracking software any required correction is made. .........
Compton
VK2HRX
QF56ne, Ryde, Sydney
VK2HRX
QF56ne, Ryde, Sydney
Re: Aligning a Rotator
Rotators should always be aligned to true north as great circle maps and maps generally are always based on true north. Magnetic north slowly varies and from memory at my QTH True North is currently about 11.5 degrees west of north compared to magnetic north. Not hard to orientate with a compass. Your beam headings will then be correct.
This website expalins it: http://www.yourhome.gov.au/passive-design/orientation
Cheers
This website expalins it: http://www.yourhome.gov.au/passive-design/orientation
Cheers
Tony
VK2TS
VK2TS
Re: Aligning a Rotator
Why not, if you insist on using magnetic north (and remembering that compasses can be affected nearby metal, magnetic fields, etc.......), make your variation to true north at the rotator when you install it? It really isn't difficult to locate true north and do the job right the first time. There are many, many mapping tools available online and on smart phones, which can all be set to default to true north.VK2HRX wrote:Got it, line them up to mag north on the mast and then account for the mag to true variation in the controller. Makes sense.VK4KHZ wrote:How it was explained to me when I initially set up the tracking software with the AZ/EL rotators is the antennas should be aligned to magnetic north and once your longitude and latitude is input into the tracking software any required correction is made. .........
Alan VK3DXE
QF21nv
QF21nv
Re: Aligning a Rotator
Actually, one of my magnetic compasses can be set to read true North, how cool is that!
I am sure I can cope with accounting for the variation.
Biggest issue will be lining up the booms to "north". I was thinking of hanging a string as loops off both ends of the 5m boom of the 23cm antenna and attaching a rod (non Fe) between the string loops and mounting the compass on the rod. Then I can see where the booms are pointed on the ground or there abouts. Then use a pipegripbighammer device to whack the Az rotator mount into the right position, tighten up with chewing gum and Bob's your Uncle.
I am sure I can cope with accounting for the variation.
Biggest issue will be lining up the booms to "north". I was thinking of hanging a string as loops off both ends of the 5m boom of the 23cm antenna and attaching a rod (non Fe) between the string loops and mounting the compass on the rod. Then I can see where the booms are pointed on the ground or there abouts. Then use a pipegripbighammer device to whack the Az rotator mount into the right position, tighten up with chewing gum and Bob's your Uncle.
Compton
VK2HRX
QF56ne, Ryde, Sydney
VK2HRX
QF56ne, Ryde, Sydney
Re: Aligning a Rotator
If there is a 23cm beacon (or signal source) at a reasonable distance and you know the direction from your location you can set your rotator to that bearing then use your big hammer to move the beam into the right direction.
Lou - VK3ALB
Being right doesn't excuse bad behaviour
Being right doesn't excuse bad behaviour
Re: Aligning a Rotator
Yep, the one at Dural. I think I could use that to get max signal and hope that its not bouncing off the neighbors house etc.VK3ALB wrote:If there is a 23cm beacon (or signal source) at a reasonable distance and you know the direction from your location you can set your rotator to that bearing then use your big hammer to move the beam into the right direction.
Compton
VK2HRX
QF56ne, Ryde, Sydney
VK2HRX
QF56ne, Ryde, Sydney
Re: Aligning a Rotator
Suddenly my interest in satellites has been re-kindled...!
What is there to work these days? I recall 10 years ago, AO-51(?) was hammering away and was all the rage..
Also, are there many non- HAM satellites that can be tracked for anything of interest?
What is there to work these days? I recall 10 years ago, AO-51(?) was hammering away and was all the rage..
Also, are there many non- HAM satellites that can be tracked for anything of interest?
Matt, VK2LK
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Re: Aligning a Rotator
Referring to my site plan provided by the Qld government my street runs E-W so I use that as reference ( true Nth)
tnx Cro
tnx Cro
Cheers
Ron cro
Ron cro