VK Logger Ham Radio Forum Archive

Hi all,
Looking at these prices $3000 and up...
www.rfsolutions.com.au/products-page/big-boy-rotators/

I've been looking at doing both hardware and software myself:
AZ
50:1 worm gearbox, 35mm thru shaft (China) $70
Stepper motor 28V with 15:1 gearbox and controller $100
EL
24" linear actuator $50
Position information
2x absolute shaft encoders $50 ea from Germany
Controller
Atmel Mega128 on PC board similar to Arduino project $25

Any one else interested in a 'kit'? Or, already have build plans and software

For your consideration

http://www.vk5dj.com/beam.html

If this is for EME, why not just build an equatorial mount, as telescopes would use? That way you just set the Declination of the moon, then clamp it down. After that, you only need to track in one axis - Right Ascension - so one motor, one controller.

It's how astronomers do it!

73 - Rob VK2GOM / G0MOH

If this is for EME, why not just build an equatorial mount, as telescopes would use? That way you just set the Declination of the moon, then clamp it down. After that, you only need to track in one axis - Right Ascension - so one motor, one controller.

It's how astronomers do it!

73 - Rob VK2GOM / G0MOH

RE: EME.
Are you sure about that Rob? The declination for the moon is always varying. Geostationary satellites or stars may be exhibit a fixed declination, but never the moon.

Ross, VK2DVZ

Hi there vk2ziw

vk2ziw wrote:Hi all, Looking at these prices $3000 and up...
http://www.rfsolutions.com.au/products- ... -rotators/
I've been looking at doing both hardware and software myself:
AZ
50:1 worm gearbox, 35mm thru shaft (China) $70
Stepper motor 28V with 15:1 gearbox and controller $100
EL
24" linear actuator $50
Position information
2x absolute shaft encoders $50 ea from Germany
Controller
Atmel Mega128 on PC board similar to Arduino project $25
Any one else interested in a 'kit'? Or, already have build plans and software

I have been aquiring bits to rotate and elevate my 12' dish for 23cm EME, I have a reversable 240v motor and gearbox from a gate opener and a beefy linear actuator but had also thought about a stepper motor and gearbox for Az instead of the 240V motor. Was wondering if you had any more info about the chinese gearbox you mention. Seeing we are on similar paths I would be interested in talking more.

Regards,
Peter Sumner, vk5pj

With the angle boxes you have to be careful about power handling , around $200.00 will get you a suitable box able to handle a small car starter which will turn quite slowly from standstill and it will handle a large array without problems , it's more than an import box but with a local supplier at least the quaility should be acceptable ? considering the intended industrial use .

VK2DVZ wrote:

RE: EME.
Are you sure about that Rob? The declination for the moon is always varying. Geostationary satellites or stars may be exhibit a fixed declination, but never the moon.

Ross, VK2DVZ

Hi Ross,

Yes declination does change, but certainly not appreciably so over the course of a night. Fractions of a degree? I don't have the exact numbers. You would still need some means to set the declination at moonrise, lock it down mechanically, then just track in RA. Even so, it could simplify operation.

73 - Rob VK2GOM / G0MOH

I've been thinking along similar lines. I've got a 2.5m dish that I need to move accurately. I also have one of the gate opener worm drives with 240V motor and was thinking of a beefy linear actuator for elevation. I would prefer absolute encoders, provided resolution is high enough. AVR would also be my choice for a micro-controller.

As you say, you should be able to do it for a reasonable price.

If you make a kit, I'll buy one!

73,
Andy VK3ES

These are the cheap gearboxes. A mate of mine brought in five, one is in Sydney for me.
Check the 90 series in 50:1 in this brochure:
www.unixservice.com.au/hamradio/rotators/WangyeWorm.pdf

alanb (at) unixservice.com.au

Polar mount to track the moon

This is very limiting. What about ham satellites? They go everywhere.

I want to use software such as HRD or SatPC32 in GS232 mode
and track whatever in AZ/EL.

Absolute encoders: I forgot to mention, 4096 steps/rev or better than 0.1 degree.

Obviously you guys want me to get crackin on the software!!!!

vk2ziw wrote:Polar mount to track the moon

This is very limiting. What about ham satellites? They go everywhere.

I want to use software such as HRD or SatPC32 in GS232 mode
and track whatever in AZ/EL.

Absolute encoders: I forgot to mention, 4096 steps/rev or better than 0.1 degree.

Obviously you guys want me to get crackin on the software!!!!

Yes please , control systems will make building the alloy parts less difficult , we await your future posts

Yes, guys, it's 5 months later, I'll get there, now in full time job.
Have an IC910H now, even more incentive.

Hi guys,
I've found some promising code:
http://forums.hrdsoftwarellc.com/showth ... ject/page2

I've signed up with the site and will be on to it. The Arduino is an ATMEL MegaXXX on a board (Jaycar)

There is a link off the UK AMSAT website under 'Projects' to an Arduino-controlled Az/El controlller. Looks fairly simple...

Here's the Link:

http://www.uk.amsat.org/info/simplesat-rotor-controller

73 - Rob VK2GOM / GW0MOH

This code looks good, BUT, The Yaesu AZ/EL rotator IS the problem:

1) Not big enough for a 5m dish.

2) Not accurate enough. the GS-232 standard is 0.1 deg accuracy.
We need to meet this. 4 deg. is SLOPPY.

3) The AtoD for AZ or EL is only 1024 positions, so, at best 0.3 deg accuracy.
Actually, for Elevation, 0 - 90 deg. only, we could meet the 0.1 deg. requirement.

4) Stepper motors will hold position and, with 400:1 gear ratio ahead of the motor,
a 100 step motor and a 4:1 microstep controller (only $50), that's 160,000 positions.
Is that fine enough? All we need is gearboxes with NO backlash, OR, add some
pre-tension. That is pretty straight forward.

Another thought: There are 3 axis magnetometers, these are useful as a 3D compass.
Unfortunately, both the MAG3110 and the HMC5883 are not good enough for Dave's 5m
dish at 1296MHz.

73s - Alan VK2ZIW

Hi all,

Full marks to John VK5DJ for his rotator board/micro design as his protocol
does 0.01 deg. accuracy. His project is not Open Source. So, only he can adapt
his code for the actual hardware you have.

Have a look at these Chinese gearboxes:
http://www.unixservice.com.au/hamradio/ ... yeWorm.pdf

73 - Alan VK2ZIW

Nearly three years have passed, and Raspberry Pies have replaced the Arduino, but, nowhere
do I see a solution for, better than 0.5deg. accuracy. Needed for a 5m dish on 23cm.

Is this correct?


Alan VK2ZIW

Building a high res rotator is mechanically easy , making the code measure count/ revs and do it accuratly is harder than I thought but we are close to done , and it will be public domain when finished which means with the right construction accuracy will be down to mechanical tollerance to work gear drives will be best

GD all,
I use a 5DJ controller and DF1SR 12 bit absolute encoders (40 Euro) on both my dishes. Prop pitch motor for Az, HD linear actuator for El....simple, never had any issues (touch wood)

Cheers

Phil VK4CDI

Would you be able to post up a pic of the azimuth mount pole etc for your large dish Phil?
73 Dave