Re: Rotator question


Neil Smith G4DBN
 

Best approach is to email the manufacturer directly, this sort of kit isn't a consumer product which you can buy off a website.  They are very common and well-known across industry, but are usually furiously expensive. The new application for the tiny ones (< 8 inches) is turning solar panel arrays, and the high volume of production means the prices have fallen. The larger ones are used for cranes and in machining systems for example. They combine a precision ground bearing ring with (usually) a worm drive.


The usual approach is to fit them to a ring flange at the top of a support pole, and fix the other side to a machined flange on a 90 degree trussed elbow, then fit another to a machined flange on the vertical face of the elbow, and the other face to a flange attached to the dish/counterweight/saddle.  Nice easy fabrication/welding/machining job. There are some videos on Youtube about using them for EME systems.


A magnetic absolute encoder chip like an AS5048A can then be used (on a compliant mount) for 14-bit rotational feedback.  OK, it aneeds a bit of precision machining to make the mount, but for £15 or so for a complete PCB, chip with SPI or I2C interface and a diametrical magnet, they are excellent value. https://www.mouser.co.uk/datasheet/2/588/AS5048-EK-AB_Operation-Manual_Rev.1.3-775916.pdf


Neil G4DBN


On 11/12/2019 11:15, Don Hawbaker wrote:
The link to the web site is not very helpful.  Exactly which model is suitable for an EME dish?  It’s not at all clear how you mount one of these things to a pole.  How big, how small?  You say $400 but I see no price list anywhere.  Shipping costs from China?  You said pulse interface.  I cannot use a pulse interface and I don’t trust them.  There are few controllers that will handle pulse.  What other interfaces are there?  Are you using just one side of a quadrature incremental output?  Is there a way to mount other position encoders?

These things are not going to be used until better sources and more information are available.

73s


On Dec 11, 2019 at 5:58 AM, <PA5Y Conrad> wrote:

If you want precision and extremely good value for money you should look at Slewing drives from China, they are 10 times stronger than ANY ham rotator, easy to fit and have very low backlash. The 3 inch ones are fine for a 3m dish in a windstorm and cost about 400 USD. You can get AZ or AZ/EL, they have pulse outputs and integrated motors and gearboxes. I have ordered a 7 inch AZ/EL drive for my 4.5m dish which I will build in the Spring.

Two companies that I or friends have had dealings with are Sunslew Ltd and Coresun drive which is a new company set up by former sunslew employees.



Prosistel PST61 is strong, I have one on my 2m EME array but I have to say that the Create RC5B3 and ERC-M combination is much smoother. I have had that rotator for a very long time and it has had some big antennas on it over the years. It is as good as it has always been and I am still using the original pot. The PST61 needs care to prevent pot failure due to water damage but touch wood I seem to have found a method that prevents this. I have a SPID-RAK but I have not used it yet. I am expecting problems. Looks like another chat with Dom F6DRO is on the cards. I hope to use this with a 2m dish for 23/13 when I find another high enough mast to get the thing above the tree line.

73

Conrad PA5Y


From: UKMicrowaves@groups.io <UKMicrowaves@groups.io> on behalf of militaryoperator via Groups.Io <Military1944@...>
Sent: 11 December 2019 11:22
To: UKMicrowaves@groups.io <UKMicrowaves@groups.io>
Subject: Re: [UKMicrowaves] Rotator question
 
 it needs 0.1 degree resolution
display, software settable end stops and offset, motor speed control for
start-stop, and RS232 or USB interfacing for PC control.
-------------------------



Naw, you need a bike.  Tyre off wheel, wheel over pole, big sprocket on a mount, bit of wood etc then a couple of bike chains and away you go. 

What did we ever do before rotators? 

Ben

-- 
Neil
<a href="http://g4dbn.uk/"><small>g4dbn.uk</small></a>

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