Antenna rotator
 

I am wondering if anyone has managed to convert/use a standard antenna
rotator for tracking purposes? I know that very expensive antenna rotators
are available for this use but hey there is no fun or challenge in that!

Want to use it to automate tracking the sun - have two solar panels mounted
on one, currently using manual control.

If you want to see what I am talking about here is a link to the picture (
bottom one) of what I am using.

http://www.flightsimulatorandhobbies.com/solar.htm

-----------------------------------------
You have hobbies. I have hobbies.
Chances are I have one that you don't.
I'll leave it up to you to decide!
http://www.flightsimulatorandhobbies.com/
-----------------------------------------

Antenna rotator
 

"JERD" wrote in message
...
I am wondering if anyone has managed to convert/use a standard antenna
rotator for tracking purposes? I know that very expensive antenna rotators
are available for this use but hey there is no fun or challenge in that!

Want to use it to automate tracking the sun - have two solar panels
mounted
on one, currently using manual control.

I invented such a thing in my head but have never built it. My idea could
be adapted to what you already have. It is quite difficult to describe
without diagrams, but I'll give it a shot.

Imagine that your rotator is reset by you each sunny morning, pointing east
at the rising sun. You flip a TRANSFER switch and westward rotator power
is then applied through the contacts of a normally-closed (NC) relay . At
that moment, however, the relay is held open with coil current provided by
the amplified signal of a photosensor which is collocated with the collector
panels. It is aimed in the same direction as the panels, but it has
blinders on it so it has only a narrow field of view in the east-west
direction. Thus, the photosensor is illuminated because it is pointing in
the direction of the sun. First thing in the morning, with the panels and
the photosensor pointing at the sun, nothing happens when you throw the
TRANSFER switch.

But wait ...
As the sun rises, it gradually moves to a point where it is NOT illuminating
the photosensor. The relay drops and energizes the rotator. The rotator
moves but an instant later, the whole rig is again aimed at the sun, which
illuminates the photosensor. The relay re-energizes, removing power from
the rotator and movement stops. This process might repeat ten or twenty
times a day, depending on the angle of view of the photosensor.

For the fans of disclaimers, let me say I fully realize the relay could be
of the normally open (NO) variety and be pulled closed when the sensor is in
shade. (I had to pick one possibility for the description.) Photosensor
means any one of several types of light-to-electricity transducers. Relays
have solid-state alternatives. The TRANSFER switch is a minor
modification of the rotator control box he's probably using now.

Clouds will louse this up. With no sunshine, the tracking process should be
halted; thus, the circuit requires the addition of an all-seeing photosensor
(no blinders) to test whether the sun is shining and interrupt the power if
it's not.

This is hardly the only autotracker design that would work and you could
even add elevation tracking.(However, in addition to all the mechanical
things, elevation tracking control would require at least another pair of
sensors and possibly a lens system rather than simple blinders. Probably
too hard.)

Automatic daily resetting could be accomplished with a dedicated
sunrise-sensing photosensor and additional modification of the control box.
This would enable you to sleep in. (You could involve the "all-seeing
photosensor," above, in this, but the logic would have to include a test for
the approximate time-of day, so the daily reset could happen only in the
morning.)

Lest anybody be concerned this has nothing to do with antennas, let me
hasten to state that my last unconventional use for an antenna rotator was
to make a true tracking polar mount for a Ku-band satellite dish. Looks
like crap but tracks the arc perfectly. So there is a tenuous connection.

"Sal"

Antenna rotator
 

Imagine that your rotator is reset by you each sunny morning, pointing
east
at the rising sun. You flip a TRANSFER switch and westward rotator
power
is then applied through the contacts of a normally-closed (NC) relay . At
that moment, however, the relay is held open with coil current provided by
the amplified signal of a photosensor which is collocated with the
collector
panels. It is aimed in the same direction as the panels, but it has
blinders on it so it has only a narrow field of view in the east-west
direction. Thus, the photosensor is illuminated because it is pointing in
the direction of the sun. First thing in the morning, with the panels and
the photosensor pointing at the sun, nothing happens when you throw the
TRANSFER switch.

But wait ...
As the sun rises, it gradually moves to a point where it is NOT
illuminating
the photosensor. The relay drops and energizes the rotator. The rotator
moves but an instant later, the whole rig is again aimed at the sun, which
illuminates the photosensor. The relay re-energizes, removing power from
the rotator and movement stops. This process might repeat ten or twenty
times a day, depending on the angle of view of the photosensor.

Surely it is much simpler than that, as long as you are only interested in
azimuth and not elevation. The trouble with photo-sensors and the like is
that there will be a problem when the sun is behind cloud, and that will
cause all sorts of 'hunting' problems.

The good thing about the sun is that you always know where it will be at any
time of the day, and the rate at which it moves, so all you have to do is
arrange a mechanism that rotates by 15 degrees an hour. If you are only
pointing solar panels the you could step in at say 15 or 30 minute
intervals, rather than have it continuously tracking.

73
Jeff

Antenna rotator
 

Likewise only a thought experiment from this end.

I favour using an old PC running Linux and whatever I/O cards are
available for the purpose. If you network the device into the ROW you
will have time of day and if you need the accuracy, the actual sun
motion numbers.

You can also use a old DOS version as that allows direct access to ports
using debug. (Finally found a use for a 286! I use to have one moving a
stepper motor ez-al array some years ago. Used 3 bits each axis from the
printer port)

From memory most rotators have a pot feedback that determines where it
is pointed. This means you need some kind of analogue input to the PC. A
joy stick port maybe? Don't forget that a sound card input could also be
used once you remove the AC coupling capacitor to its A/D.

So after calibrating the system for azimuth vs input volts you have a
lookup table that you can base your command on. You can use serial or
parallel port pins to actuate the motor.

Problem of course is that the PC uses a considerable amount of the
energy gained from the array just to run itself! You could of course
automatically sleep and wake it every 30 minutes or so!

Another possibility - Your rotator controller either has a direct
feedback to a position knob or a display and CW/CCW switch? Should be
pretty easy to use the feedback knob/display meter volts/comparator to
actuate the drive. Just create an analogue lookup table with a simple
4-8 bit TTL/CMOS counter and a stack of resistors and you are away! It
would even reset itself for the start of the new day. Only real problem
is where you source the counter clock from.

Cheers Bob VK2YQA

JERD wrote:
I am wondering if anyone has managed to convert/use a standard antenna
rotator for tracking purposes? I know that very expensive antenna rotators
are available for this use but hey there is no fun or challenge in that!

Antenna rotator
 

"Jeff" wrote in message
. com...
The trouble with photo-sensors and the like is
that there will be a problem when the sun is behind cloud, and that will
cause all sorts of 'hunting' problems.

No, there won't be hunting. First, there is one photsensor that has no
blinders. It senses the presence of sun -- anywhere. When a cloud obscures
the sun, it inhibits tracking.

Second, the tracker only goes in one direction, advancing ever-westward,
automatically following the sun by steps, assuming a sunny day. Recall, I
said the shining of the sun onto the photosensor is what stops the advance
and the loss of sunshine onto the sensor restarts the advance.


The good thing about the sun is that you always know where it will be at
any
time of the day, and the rate at which it moves, so all you have to do is
arrange a mechanism that rotates by 15 degrees an hour.

Describe your mechanism. Making the version I originally described requires
only two photosensors, a dual DC amplifier chip, two relay driver modules,
two relays, a switch, a small prototyping board and some wire.

Antenna rotator
 

"JERD" wrote in news:bgt0j.14841$CN4.8264
@news-server.bigpond.net.au:

http://www.flightsimulatorandhobbies.com/solar.htm

It doesn't seem that you have any adjustment of the elevation, and that you
are just going to drive the azimuth.

If that is the case, why not just drive it from a clock, ie the azimuth
angle calculated or looked up from hour of day.

BTW, this is hardly an optimised pointing.

You comment about 15°/hr is applicable to an hour angle / declination
mount... but that isn't what is in the picture.

Owen

Antenna rotator
 

that there will be a problem when the sun is behind cloud, and that will
cause all sorts of 'hunting' problems.

No, there won't be hunting. First, there is one photsensor that has no
blinders. It senses the presence of sun -- anywhere. When a cloud
obscures
the sun, it inhibits tracking.

Second, the tracker only goes in one direction, advancing ever-westward,
automatically following the sun by steps, assuming a sunny day. Recall, I
said the shining of the sun onto the photosensor is what stops the advance
and the loss of sunshine onto the sensor restarts the advance.


The system works unitil it gets out of sync for some reason. A leaf
obscuring a sensor, a bird sitting on it etc etc.
One the rotator gets ahead of itself it will never find the sun.


The good thing about the sun is that you always know where it will be at
any
time of the day, and the rate at which it moves, so all you have to do is
arrange a mechanism that rotates by 15 degrees an hour.

Describe your mechanism. Making the version I originally described
requires
only two photosensors, a dual DC amplifier chip, two relay driver modules,
two relays, a switch, a small prototyping board and some wire.


The actual system will depend on what type of rotator you are using, a
stepper motor would be the easiest since you know how many degrees each step
is. If you are using an 'normal' antenna' rotator then most have a feedback
pot, and a control pot. All you have to do is apply a voltage in place of
the control pot to get your desired position. There are many ways of doing
that from a computer, a micro controller, a counter chip feeding a d/a
converter. a series of relays switching in resistors, the list is almost
endless.

73
Jeff

Antenna rotator
 

"Jeff" wrote in message
. com...

snip

The system works unitil it gets out of sync for some reason. A leaf
obscuring a sensor, a bird sitting on it etc etc.
One the rotator gets ahead of itself it will never find the sun.

This is true.Perhaps multiple sensors to some OR gates would provide the
necessary redundancy. I provided only one fail-safe mechanism and that is
for a cloud.

snip

The actual system will depend on what type of rotator you are using, a
stepper motor would be the easiest since you know how many degrees each
step
is. If you are using an 'normal' antenna' rotator then most have a
feedback
pot, and a control pot. All you have to do is apply a voltage in place of
the control pot to get your desired position. There are many ways of doing
that from a computer, a micro controller, a counter chip feeding a d/a
converter. a series of relays switching in resistors, the list is almost
endless.

What, no hamsters? :-)

Seriously, OP "JERD" never said whether he wanted a complicated, highly
accurate setup or just something that works. I went for bare-bones, basic
El Cheapo, the most fun, IMHO.

(I have more of a history of jury rigging antenna rotators than most people.
My first [1968] was the building of a controller based on two doorbell
pushbuttons from the hardware store; I bought the correct transformer and
capacitor from the electronics store. No indicator ... We aimed it solely
by looking at the TV. The components were screwed down to a chunk of
plywood I found in the yard. Oy! But I was a young sailor living in town
on my own dime for the first time. After rent and utilities, there was beer
money and not much else.)

73
"Sal"

Antenna rotator
 

On Nov 20, 3:41 am, "Sal M. Onella"
wrote:
"JERD" wrote in message

.. . . . . .
have solid-state alternatives. The TRANSFER switch is a minor
modification of the rotator control box he's probably using now.

Clouds will louse this up.

Use an infrared sensor.

"Sal"

w3rv

Antenna rotator
 

"Brian Kelly" wrote in message
...
On Nov 20, 3:41 am, "Sal M. Onella"
wrote:
"JERD" wrote in message

. . . . . .
have solid-state alternatives. The TRANSFER switch is a minor
modification of the rotator control box he's probably using now.

Clouds will louse this up.

Use an infrared sensor.

"Sal"



Or U/V, maybe. No wonder we enjoy so much good stuff -- there is no end to
the ingenuity. Thanks, Brian.

BTW, I don't see the OP back in here. He may be out buying photosensors and
relays. Ya' think?

Antenna rotator
 

"Sal M. Onella" wrote in message
...

"Sal"



Or U/V, maybe. No wonder we enjoy so much good stuff -- there is no end to
the ingenuity. Thanks, Brian.

BTW, I don't see the OP back in here. He may be out buying photosensors
and
relays. Ya' think?



Hi Guys, original poster still here and taking it all in!

Had some interesting posts and leads which I am following up.

JERD

Antenna rotator
 

Bob Miller wrote:
On Tue, 20 Nov 2007 04:20:23 GMT, "JERD"
wrote:

To track a celestial body like the sun, you may need an equitorial
mount as is used on telescopes. Do a Google search on that type of
mount, to see what it is. And then, if you can combine it with a TV
rotator, voila...

There is a simple, elegant and more expensive means: Buy a Yaesu az/el
rotor as for satellite operation. Connect the control box through a
SASI tracker or similar device and use Nova or some other sat tracking
program. Almost all of the Keplerian element lists include the sun.

Dave Heil K8MN

Antenna rotator
 

"Dave Heil" wrote in message
...
Bob Miller wrote:
On Tue, 20 Nov 2007 04:20:23 GMT, "JERD"
wrote:

To track a celestial body like the sun, you may need an equitorial
mount as is used on telescopes. Do a Google search on that type of
mount, to see what it is. And then, if you can combine it with a TV
rotator, voila...

There is a simple, elegant and more expensive means: Buy a Yaesu az/el
rotor as for satellite operation. Connect the control box through a
SASI tracker or similar device and use Nova or some other sat tracking
program. Almost all of the Keplerian element lists include the sun.

Dave Heil K8MN

Yes, but I do believe it's overkill. The payback is in forever-land when
you're making a few dollars worth of juice per year. (Of course, if it's a
learning exercise, then the cost need not be a concern.)

More to the point, I did some checking on this very thing with a guy I know
who does EME and I can confirm it: The antenna auto-track software commonly
has the sun and moon ready to go. I wondered why at first, not so much for
the moon, but for the sun. Then he explained that the sun is an alignment
shortcut. i.e, if you set your rig to follow the sun, you can then
mechanically refine its alignment to the sun and it will presumably be
correct, as to its azimuth and elevation. Then, any other pointing it does
will presumably also be correct.

People who have actually done this, or been close-by, should feel free to
jump in if there is more that needs to be said.

Antenna rotator
 

There is a simple, elegant and more expensive means: Buy a Yaesu az/el
rotor as for satellite operation. Connect the control box through a
SASI tracker or similar device and use Nova or some other sat tracking
program. Almost all of the Keplerian element lists include the sun.

Dave Heil K8MN
Yes, but I do believe it's overkill.

Could be. I guess it depends on how precisely the sun panels need to
be pointed at the sun. Most solar panels are fixed in position, on a
house top or whatever, just to generally catch the rays.
=======================
Yes to a fixed position due SOUTH ,but it means the panels will not
receive all that much energy or very little during the post noon
daylight hours .
It is debatable how much that is and consequently whether a rotating
system would be justifiable. However to find out and possibly advise
people ,after this test, how much more energy can be trapped ,I feel
setting up a rotating solar panel system is a worthwhile effort.
As an alternative to K8MN's suggestion a low cost (modified)satTV
tracking system might prove suitable.

Frank GM0CSZ / KN6WH

Antenna rotator
 

Could be. I guess it depends on how precisely the sun panels need to
be pointed at the sun. Most solar panels are fixed in position, on a
house top or whatever, just to generally catch the rays.
=======================
Yes to a fixed position due SOUTH ,but it means the panels will not
receive all that much energy or very little during the post noon daylight
hours .
It is debatable how much that is and consequently whether a rotating
system would be justifiable. However to find out and possibly advise
people ,after this test, how much more energy can be trapped ,I feel
setting up a rotating solar panel system is a worthwhile effort.
As an alternative to K8MN's suggestion a low cost (modified)satTV tracking
system might prove suitable.

Frank GM0CSZ / KN6WH

It is generally agreed that by tracking the sun one gets approx 40% more
'energy' from ones solar panels. Accuracy is not important. 10-20 degrees
tracking accuracy is suitable.

I have updated my solar page if you are interested:

http://www.flightsimulatorandhobbies.com/solar.htm

JERD
VK5JE - (Original poster)

Antenna rotator
 

It is generally agreed that by tracking the sun one gets approx 40%
more
'energy' from ones solar panels. Accuracy is not important. 10-20 degrees
tracking accuracy is suitable.

I have updated my solar page if you are interested:

http://www.flightsimulatorandhobbies.com/solar.htm
=============================
Tnx for above info , 40% additional energy is indeed worth it to have a
rotating system . I bookmarked your web site.
I have 2pcs 64W solar panels producing up to 8 Amperes together.
Together with a 150W max (12 Amperes) Wind generator they keep my 12V
SLA batteries happy ,except in a windless winter period (location
northern Scotland at 57 degr north)
I am now considering to put a 2V-200A lead-acid cell in series to get
minimum 14 V , since my TenTec Paragon transceiver (1980s vintage)
doesn't like supply voltage to be below 12.2 Volt
The solar panels have a rated capacity at up to 16.5 volts ,so with 14 V
(max 16 V) I can still keep them in parallel.
The batteries provide power to an up to 100W-RF HF Tranceiver ,a laptop
(via a DC to AC inverter),a Packet-TNC , a VHF- transceiver , desk
lighting and NiMH battery charger.

Frank GM0CSZ /KN6WH

Antenna rotator
 

Highland Ham wrote:
There is a simple, elegant and more expensive means: Buy a Yaesu az/el
rotor as for satellite operation. Connect the control box through a
SASI tracker or similar device and use Nova or some other sat tracking
program. Almost all of the Keplerian element lists include the sun.

Dave Heil K8MN

Yes, but I do believe it's overkill.


Could be. I guess it depends on how precisely the sun panels need to
be pointed at the sun. Most solar panels are fixed in position, on a
house top or whatever, just to generally catch the rays.

=======================
Yes to a fixed position due SOUTH ,but it means the panels will not
receive all that much energy or very little during the post noon
daylight hours .
It is debatable how much that is and consequently whether a rotating
system would be justifiable.

One can fairly trivially calculate this, at least in terms of the
incident energy on a flat plate. Taking into account the efficiency
changes in the solar panel is a bit trickier.

As a start, consider a panel tilted so that it directly faces the sun at
noon, and to make things easy, assume we're at the equinox. The angle
varies from -90 to 0 to 90 over a span of 12 hours. So, the average
insolation is the integral of cos(theta) from -pi/2 to pi/2 divided by
pi, or, 2/pi... about 0.63... So, pointing right at the sun would pick
up about 50% over the day. (assuming you've got view from horizon to
horizon, and neglecting the loss due to atmospheric attenuation, which
is significant)

Depending on what you consider as your energy costs, you can decide if
it's worth it. A typical solar panel installation runs about $6-7/watt,
so the improvement due to tracking would let you install a 35% smaller
installation, for the same output, equivalent to paying only $4-5/watt.
On a 1kW system, this is several thousand dollars, which might
actually get close to the cost of the actuators.

There IS a reliability and maintenance costs issue to consider though..


However to find out and possibly advise
people ,after this test, how much more energy can be trapped ,I feel
setting up a rotating solar panel system is a worthwhile effort.
As an alternative to K8MN's suggestion a low cost (modified)satTV
tracking system might prove suitable.

Frank GM0CSZ / KN6WH

Antenna rotator
 

I have 2pcs 64W solar panels producing up to 8 Amperes together.
Together with a 150W max (12 Amperes) Wind generator they keep my 12V SLA
batteries happy ,except in a windless winter period (location northern
Scotland at 57 degr north)

Frank GM0CSZ /KN6WH

Frank, please tell me about your wind generator.

VK5JE

http://www.flightsimulatorandhobbies.com/