I have had some success in adapting my SPID RAS to my W2DRZ controller using incremental
encoders. First I removed the plastic cap covering the original sensor housing. Then I
removed the magnetic switch and standoff connector board. That exposes the worm gear from
the motor and the ring gear that drives the second worm gear. By some fortunate luck, the
second worm gear is drilled out. It takes about a 7 mm rod. I used a bolt with the head
cut off. I measured the depth of the drilled out hole. At a location on the rod where it
can fit flush against the ring gear when the rod is inserted into the hole, I spot welded
a washer that was a tight fit to the rod. Then fortunately there is a drilled and tapped
hole in the ring gear. 4 mm I think, don't remember. I drilled a hole in the washer
and fastened the assembly flat to the ring gear with a screw. I then carefully drilled a
hole dead center in the original plastic cover. I made the rod long enough so that it
protruded through the cover enough to accept a shaft coupler. I tapped two of the
original cover mounting holes to accept machine screws. Then I cut two aluminum rods that
were long enough to offset the incremental sensor from the rod shaft so that a coupler
would fit between the two shafts. The sensor is mounted on an aluminum plate which I
drilled to line up with the rods. The rods are tapped on each end for machine screws. I
used studs on the bottom ends. You could use rubber pipe for the shaft coupler if you are
unsure about alignment or if the shafts are two different sizes. Then I installed power
poles on the motor wires and reconnected them. I need to waterproof them at a future
date, but for now I am just using a zip lock plastic bag to cover the whole thing,
The sensor is an inexpensive Chinese incremental model. Costs about $14 on eBay. Is 600
pulses per revolution. At first I was using one of the original encoders, 2500 p/r, but
at the 90 to 1 gearing at the SPID access point, it was overloading the PIC processor with
pulses. Pulses were being missed. I have a 100 p/r sensor on order with z pulse. I have
not tested a z pulse yet. I plan to do that as soon as the sensor arrives. But I am not
worried about it right now as I am so happy with the results. It's really nice to
have some confidence that you know where the dish is pointed.
I am using the original 2500 p/r inclinometer on the elevation. It seems to work okay.
When I was first testing, I left the magnetic reed switch hooked up. I calibrated both to
the same reading. Within only a few minutes of jockeying the elevation, the SPID
controller was off 4 degrees.
I would be interested to hear what others have done. Maybe there is a better way. I have
only had the system operating for a few days, so I don't have a lot of experience with
it yet. And now I have to go out of town for two weeks, but I thought I would post this
now to stimulate others to think about how to do this. There may be better hardware or a
better design. I am negotiating now to buy an HR upgrade for my other dish (I have one
each at my summer home and my winter home). I think, but I am not sure, that they are
using encoders of some kind on the upgrade, but it is extremely hard to get any
information from SPID or SPID suppliers. With the system I have now, I know I will be
able to get parts and maintain it.
From: moon-net-bounces(a)mailman.pe1itr.com <moon-net-bounces(a)mailman.pe1itr.com> on
behalf of g4bao <john(a)g4bao.com>
Sent: Friday, June 9, 2017 5:59:25 AM
To: Ukmicrowaves (ukmicrowaves(a)yahoogroups.com)
Cc: microwave(a)lists.eclectechs.com; microwave valinet; moon(a)moonbounce.info; Moon-Net
Subject: Re: [Moon-Net] [ukmicrowaves] Fitting MAB25 type encoders to a Spid RAS
Yes I've successfully completed the mods and will write up the work in due course.
On 9 Jun 2017 10:01, "Donald Hawbaker
Have you made any progress on this project? I recently began using a DRO Machine readout
for elevation. It's the only way I can tell where my elevation is pointed. After
only a few minutes of bumping the elevation up and down, the SPID readout is off by 6
degrees. Don't have a solution for azimuth. I am experimenting with the higher bands
now, so something has got to be done. I guess I will first take a look at what is going
on, what do the pulses look like, do I have excessive noise. I have already moved the
sense circuits to a seperate cable, but no help. It still miscounts. Maybe look at
shielded cable, but in such a system, it's hard to tell exactly where is ground. 73
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On Thursday, February 9, 2017, 12:58 PM, g4bao firstname.lastname@example.org<mailto:email@example.com>
Befefore I reinvent the wheel this spring and before I strip down my RAS, has anyone out
there fitted absolute rotary encoders of the MAB 25 style to a SPID RAS and more
importantly documented it?
Also if anyone has stripped down and rebuilt a RAS I'd be interested in any tips,
pitfalls and gotchas.
I used to regularly strip down and rebuild a a Suzuki T500 charger engine in my youth,so
I'm not scared to have a go but I had a Haynes manual!
You could save me a lot of time and headscratching.
Also an exploded diagram of the rotator would be nice
Answers on a postcard to.......
Posted by: Donald Hawbaker
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