SETI Clock Release

[James Brown]

I have posted the latest version of the SETI Net Astronomical Clock ready to download.
This Windows application (32 bit) converts between RA/Dec and Az/El and shows your position on a Star Map.
http://www.seti.net/Operations/Operations.php#Clock

[Lawrence Mayfield]

Wow, I am new to amateur radio astronomy and with guidance provided by the entirety of this SETI.net and a noobs cook book provided by  another new friend I think I can do this!  I thank all of you folk who have contributed to this effort, I know how hard it can be sometimes.  Is there a specific place on SETI .net where I can ask questions in regards to specifics of certain things?  Right now I am struggling with antenna pointing and control trying to figure it out on my own and not succeeding.  The antenna shown in the block diagram uses what I want for my set up and observatory. I have been trying to modify the system to have an equatorial system for pointing but that is proving difficult for me. I like alt-az but that escapes me also.  Just finding hardware to implement is difficult and then control is right there on the difficulty scale. And I am a fairly competent old guy lol.  I liken the situation to being in a stadium full of experts and when I  ask a question, getting a set of replies that is in an alien language.  So, James, oh, may I call you that? If I send you a question can you forward it to one of your associates who is the expert in that area for me?  I am going to head over to the hardware tap on the seti.net home page and see what I can find there. Bravo to you and the folks who put this together!!

mayf (my nickname of more than 50 years)

Lawrence Mayfield

Pahrump, NV

Retired Boeing Company Aerospace Manager ( last assignment was in Huntsville, Al., as the Test Program Manager for the Space Station 1990 - 1997)

[Jeff Kruth]

Hi Mayf!

I have been reading your emails and if I interpret correctly, you are asking how to move and point your dish (old sat dish?). Everything seems hard at first but the more research you do, the simpler it becomes. Point is others have done it. In the front of a Calculus book I have there is a quote; "What one fool has done, so may another".

Positioners are hard to find. I have a collection amassed over the last 45 years. Was not easy to get. If you can gather the info below, you will be on the way to figuring out what to do. Ham radio guys (which I am one) do moonbounce comms which require moontracking. They have used dishes from 1 meter to 10 meters and up in diameter. Some of the homemade positioner systems are quite good and very clever. Easy = Lots of $, more elbow grease = less $. Ingenuity is king here.

First question: What is the mass and wind loading potential of the dish (static and dynamic loads)?

This tells you what loads the bearings and gears/drives need to hold and survive. Fairly easy to determine based on weight and size of dish, max wind speeds in your locale.

I have used beefy camera mounts with counterweights (usually necessary) for some small projects.

(Always steer to "Stow" position when done (birdbath), reduces wind loading.)

Second question: What readout mechanism do you need?

This will be driven by your beamwidth of the dish. If you have  a 5 degree BW dish, you do not need .001 degree accuracy, .5 degree might be sufficient and is obtainable with potentiometers/dc supplies/A/D converters (10 bit for AZ and 8 bit for EL).

Corollary: absolute or relative shaft encoding. Absolute more expensive but doesnt forget where you are when the power goes out (cheaper these days than in the past). Relative is dirt cheap, but "0" needs to be calibrated when power out.

(This question presupposes you do not use Pots, which are a very cheap form of absolute encoder.)

Third Question: Motor drives?  DC motors are common on large pedestals and small (my camera mounts are 120V DC). 120 Volt field and armature. Easy to drive these days with H bridges and all the modern control stuff.  Steppers geared down to increase torque can be used on small stuff., relative cheap and computer controllable interface is easy.

Anyway, this is a start. Hopefully something you can use here (hope I didnt plow ground already tilled!).  As you are no doubt aware the mechanics is troublesome. BTW, dish people do not use equatorial anymore, only did that in the early '60's when "computers do not have the horsepower to do the math!" (Ha they were wrong, by the time the 140 footer at Greenbank was done, computers had caught up!)

Folks have used rear-ends from pickup trucks to build Az drives (needs to be the beefiest one as holds all the stuff).  El mechanics are more simple, just a knuckle and a gear, maybe even chain drive.  Old radar pedestals were used in the past, harder to find these days.  Useful for ideas through (look at the bicycle chain drive gearing of a WWII SCR-584 S band radar, should be able to find drawings on line, used bicycle gears and chains for drive, flexible coupling and gear reduction). Motorcycle chains, sprockets etc are beefy enough for most amateur needs. Backlash may be an issue but not so much if your BW is higher and you use reduction drive as well.

If you have any questions, do not hesitate to ask. I am an old defense industry guy (microwave engineer, EW & Radar, 30 years)  who teaches at a University in Ky, We have a 21 meter dish (new) that we use for tracking and R-A. I build the receivers for it and manage it.

Good luck, this is fun stuff.

Regards,

Jeff Kruth

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[Larry Mayfield]

Jeff! Many thanks for the reply and the assistance. First a bit about me: I am retired Engineer from Boeing. I finished my career with Boeing as the international space station test program manager in Huntsville, Alabama.  I have been in test all of my technical life in some form or fashion. Before the space station I worked in Oak Ridge on classified projects for Boeing and interspersed were aerospace programs in national defense. I have a pretty fair amount of training (BS degree in Aeronautical Engineering, Master of Engineering degree a pair of advanced degrees along with  lots of special course work) and am currently and still a registered professional engineer in Washington State.  And I am old, lol.  And not one of my skills, except for analysis capabilities of all sorts, applies to electronics and electromagnetics!  As an old test guy, reliability is one of my key requirements for a dish observatory system, especially since I am getting too old to be rebuilding stuff all the time.   When I think of reliability, I think robustness, or in my words, over built. In the test world our test hardware and set ups had to be repeatable and reusable time after time because of expense of missed schedules and high costs involved in repair and rework.

 

Now having set the stage, let’s look at some of my problems that need help.  Well, most of them, lol.  I put the thoughts and comments down in line in green. You game? Ok, here we go!

 

From: 'Jeff Kruth' via Society of Amateur Radio Astronomers [mailto:sara...@googlegroups.com]
Sent: Monday, May 28, 2018 10:59 AM
To: drm...@mayfco.com; sara...@googlegroups.com
Subject: Re: [SARA] Re: Az-El mechanisms for dish positioner

 

Hi Mayf!

I have been reading your emails and if I interpret correctly, you are asking how to move and point your dish (old sat dish?). Everything seems hard at first but the more research you do, the simpler it becomes. Point is others have done it. In the front of a Calculus book I have there is a quote; "What one fool has done, so may another". Yeah, I am mostly one of those fools!  And I love math!

 

Positioners are hard to find. I have a collection amassed over the last 45 years. Was not easy to get. If you can gather the info below, you will be on the way to figuring out what to do. Ham radio guys (which I am one) do moonbounce comms which require moontracking. They have used dishes from 1 meter to 10 meters and up in diameter. Some of the homemade positioner systems are quite good and very clever. Easy = Lots of $, more elbow grease = less $. Ingenuity is king here. The dish I acquired had a positioner screw jack on it for horizontal movement along the geosynchronous orbit to align other satellites.  But the old geezer who gave me the dish ( a longtime friend), tossed the control box when he changed to a small digital dish.  I have that hardware but not he control and voltage source for it. And of course the mfg tag is weathered beyond any recognition as to make and model so I have no idea as to even the voltage it uses. I suspect it is 12 or 24 volts DC with a switch in the control box to swap polarity on voltage so it can go either way. You have any idea as to what voltages those critters might use?  My dish is a 2.2 meter dish.  I do mine with the notion that I am saving money by building stuff on my own, a habit and it gives me some amount of happiness to build and see it work.  

 

First question: What is the mass and wind loading potential of the dish (static and dynamic loads)? Well the dish was previously installed fairly locally so the mount and mast or pole are sufficient to withstand the local winds. I will be using the same hardware for the mount unless I change to alt-az type. And the dish is a mesh dish so wind can relieve itself. Two of us old geezers picked up the dish after removal from the mount and it might have weighed 25 or 30 pounds. The c-band feed horn weighs a few pounds.  My new ball bearing pillow blocks for the RA axis are good for I think 5000 pounds. Dynamic loads are slim to none. Oscillations will be small in amplitude and so the loads will be small as well. However, I have some structural dynamic software that I can and will ultimately use to analyze the vibrations etc due to positioning and wind loads.  Since it essentially worked for the sat system, I do not expect it to be changed much.  I do have a question here though: how deep should the mast or pole be set into the soil? We are not is a major freeze area and rarely ever have surface ice or frost even on the very coldest days. No water here in the desert, lol. Cold but no ice.

 

This tells you what loads the bearings and gears/drives need to hold and survive. Fairly easy to determine based on weight and size of dish, max wind speeds in your locale. Again, I will be using what seems to have worked for others if I can find others using the systems. I am not into reinventing the wheel. Being a test guy, I am a pretty fair structural analysist with both structures and dynamics. So all get the analysis treatment when designs are finalized.

 

I have used beefy camera mounts with counterweights (usually necessary) for some small projects.

(Always steer to "Stow" position when done (birdbath), reduces wind loading.) A consideration not considered. Now it will be. Drift mode storage, so to speak. I would have no issue with it remaining as if in use because that is the way that sat dishes hang out. Always pointing to the target or object.

 

Second question: What readout mechanism do you need? Ok, this is one of the major issues. But being an old engineer, I look around for stuff that can be repurposed. Like inclinometers or angle finders. Electronic. Amazon has some that are less than 30 bucks that can read degrees to 3 decimal places with some accuracy.  My plan was to use this doohickey to set the elevation manually at the vernal equinox position. Or when the RA position is mid travel. The simply move the dish manually in elevation, tighten fasteners and record angle. A recordable measurement would be fantastic but I have no idea as to what is used in the Radio Astronomy  units.  You have suggestions for both axes that can be recorded as a function of sidereal time? Or is that even the right kind of terminology? That might explain why I have issues finding stuff sometimes – wrong terminology… Suggestions? Cheap is better, lol but has to be useful as well.

 

This will be driven by your beamwidth of the dish. If you have  a 5 degree BW dish, you do not need .001 degree accuracy, .5 degree might be sufficient and is obtainable with potentiometers/dc supplies/A/D converters (10 bit for AZ and 8 bit for EL). I can record 16 channels of data if I get the stuff off of my race car. They have AD converter built in but probably not that accurately. I do have a desktop that can record that but some signal conditioning is going to be required to get the electrons from the measurement location, about 100 feet away to the computer. And I have quite a number of instrumentation cards for that desktop.  So, what do you suggest?

 

Corollary: absolute or relative shaft encoding. Absolute more expensive but doesnt forget where you are when the power goes out (cheaper these days than in the past). Relative is dirt cheap, but "0" needs to be calibrated when power out.

(This question presupposes you do not use Pots, which are a very cheap form of absolute encoder.) Encoders require electronics. More reliability issues. Pull pots and simple voltage devices and if used with a reliable power supply then likely ok at least for first light operations.  I am not taking photographs merely listening to ET phoning home.  And that signal voltage can be calibrated for pointing data as well. Other sensors can be used as well, like 3 axis solid state gyros with  integrated outputs.  Pots are ok for now and I will get busy sourcing some for my use. I do have a pair of limit switches to remove drive power when the system reaches the limits of rang of interest.

 

Third Question: Motor drives?  DC motors are common on large pedestals and small (my camera mounts are 120V DC). 120 Volt field and armature. Easy to drive these days with H bridges and all the modern control stuff.  Steppers geared down to increase torque can be used on small stuff., relative cheap and computer controllable interface is easy. I have several 90 volt DC motors of ½ hp but run at 1750 rpm, I also have a motor controller for those as well but only one at a time. Reasonably expensive.  I have one motor with planetary gear set on end that is about 1/3 hp and output rpm of 345 rpm max.   Open to suggestions for drives and controllers and gear boxes etc? What works for someone else will work for me as well..

 

Anyway, this is a start. Hopefully something you can use here (hope I didnt plow ground already tilled!).  As you are no doubt aware the mechanics is troublesome. BTW, dish people do not use equatorial anymore, only did that in the early '60's when "computers do not have the horsepower to do the math!" (Ha they were wrong, by the time the 140 footer at Greenbank was done, computers had caught up!). Old is not bad. Look at me, lol. Not everything needs to be thrown out for automation.  

 

Folks have used rear-ends from pickup trucks to build Az drives (needs to be the beefiest one as holds all the stuff).  El mechanics are more simple, just a knuckle and a gear, maybe even chain drive.  Old radar pedestals were used in the past, harder to find these days.  Useful for ideas through (look at the bicycle chain drive gearing of a WWII SCR-584 S band radar, should be able to find drawings on line, used bicycle gears and chains for drive, flexible coupling and gear reduction). Motorcycle chains, sprockets etc are beefy enough for most amateur needs. Backlash may be an issue but not so much if your BW is higher and you use reduction drive as well. Interesting you should mention automotive parts.  My first iteration of the system was to use a floating axle hub from at least a one ton truck as the az mount/drive.  And a front replaceable spindle bearing mount for the el axis.  These pieces are virtually indestructible and are certainly weather resistant.   I have a 12 inch diameter pipe that was going to be my vertical mount.  Of course, the flange mount pillow blocks for the el mount is cheaper and simpler to use. No fancy machine work to install them.  You do and have hit on one of my major questions. And that is pointing accuracy.  Not sure how to determine how or what is good enough to listen to a star’s planetary system. At < 20 light years away.  I want to look at all the Keppler discoveries at that distance before moving further out.   Seems to me that if all want to do is listen for ET signals and skip the science aspect of observing, then pointing may not be so very accurate. Your thoughts?  I have and am stil considering chain drives coupled with gear boxes and variable speed motors.  Chain is rugged.

 

If you have any questions, do not hesitate to ask. I am an old defense industry guy (microwave engineer, EW & Radar, 30 years)  who teaches at a University in Ky, We have a 21 meter dish (new) that we use for tracking and R-A. I build the receivers for it and manage it. Sounds like you are my go to guy! I have asked a few questions that are bugging me above so take a gander and see if there is any hope for me, lol….

 

Good luck, this is fun stuff.

Regards,

Jeff Kruth

 

Yes, it is going to be fun, and in fact just building the stuff is fun. That was the way if was with the race car. I own a Sunbeam Tiger and I found out that Sunbeam was the very first car to set an official record over 200 mph and that was in March of 1927. No other Sunnbeam has ever gone faster than that…until me in Sept 2010. I went for a flying mile average of 204.912 mph with an exit speed of 210.779 mph but still had 600 or so ropm in the motor to go but said nope I am done, lol. Broke an 80 + year old Sunbeam record. I now have the fastest Sunbeam on planet earth. I winder if ET wodl like to know that? Maybe I’ll send them a radiogram, eh?

 

Mayf, my nickname of more than 50 years so please call me that, all my friends do.  

 

 

 

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To unsubscribe from this group, send email to

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[Paul Oxley]

Mayf

No Green = No Problems ???

I am also a retired Engineer from AT&T. RA is a good hobby to keep my brain working.

Paul

---

From: Larry Mayfield <drm...@mayfco.com>
To: sara...@googlegroups.com
Sent: Tuesday, May 29, 2018 12:56 PM
Subject: RE: [SARA] Re: Az-El mechanisms for dish positioner

[Larry Mayfield]

Wuz green when I sent it out, lol. I kept a copy in my Radio A file.  I am guessing you have html turned off…  I use MS Office 2013 Outlook for email. What client are you using? How about in the forum itself?  Send me your email addy and I will forward directly to you and yes, lots of questions etc… Probably my bad some how…

 

mayf

[James Brown]

Good to hear from you Larry

I, like you, spent my time in testing (Poseidon, Polaris, Trident missile systems) for Lockheed in Sunnyvale, F16 Fire control RADAR test system for General Dynamics and M1 tank for SAIC. I invented the IETM used in place of tech manuals in the field for the Army. Also like you, I’m an old guy.

My advice to you is to start with the receiver. My station and others build like it use SDRs in place of analog receivers no days. They are cheaper and better. Get yourself a small antenna that covers up to 1.5 GHz and hook it to the SDR receiver. Get that going first. EBay has a ton of SDRs (Amazon as well) and they are all pretty much alike.

I just got my system up and running again after breaking the elevation motor and replacing it. You can follow my trials at:

http://www.seti.net/engineering/engineering.php

Look back over the ‘earlier chapters for details.

Follow my Facebook posts at:

 

https://www.facebook.com/seti.net

 

Friend me and I’ll connect you with the rest of the group

Regards....... Jim 

[Paul Oxley]

Mayf

I use a Goggle Chrome browser. Colors are present, but all were blue or black on your message.

Your latest message is in blue except for the headings which are black.

Paul

---

From: Larry Mayfield <drm...@mayfco.com>
To: sara...@googlegroups.com

Sent: Tuesday, May 29, 2018 1:30 PM

[Larry Mayfield]

Resending this because no color on forum Iguess. So my bad. I put my responses at the end sof original message in quote marks. Forgive me. I an =m a noob and when forum stuff comes directly to my desktop I was lulled into thinking it waws direct to me from members. My bad…

 

I’ll do better…

 

mayf

 

From: Larry Mayfield [mailto:drm...@mayfco.com]
Sent: Tuesday, May 29, 2018 9:56 AM
To: 'sara...@googlegroups.com' <sara...@googlegroups.com>
Subject: RE: [SARA] Re: Az-El mechanisms for dish positioner

 

“Jeff! Many thanks for the reply and the assistance. First a bit about me: I am retired Engineer from Boeing. I finished my career with Boeing as the international space station test program manager in Huntsville, Alabama.  I have been in test all of my technical life in some form or fashion. Before the space station I worked in Oak Ridge on classified projects for Boeing and interspersed were aerospace programs in national defense. I have a pretty fair amount of training (BS degree in Aeronautical Engineering, Master of Engineering degree a pair of advanced degrees along with  lots of special course work) and am currently and still a registered professional engineer in Washington State.  And I am old, lol.  And not one of my skills, except for analysis capabilities of all sorts, applies to electronics and electromagnetics!  As an old test guy, reliability is one of my key requirements for a dish observatory system, especially since I am getting too old to be rebuilding stuff all the time.   When I think of reliability, I think robustness, or in my words, over built. In the test world our test hardware and set ups had to be repeatable and reusable time after time because of expense of missed schedules and high costs involved in repair and rework.

 

Now having set the stage, let’s look at some of my problems that need help.  Well, most of them, lol.  I put the thoughts and comments down in line in green. You game? Ok, here we go!”

 

From: 'Jeff Kruth' via Society of Amateur Radio Astronomers [mailto:sara...@googlegroups.com]
Sent: Monday, May 28, 2018 10:59 AM
To: drm...@mayfco.com; sara...@googlegroups.com
Subject: Re: [SARA] Re: Az-El mechanisms for dish positioner

 

Hi Mayf!

I have been reading your emails and if I interpret correctly, you are asking how to move and point your dish (old sat dish?). Everything seems hard at first but the more research you do, the simpler it becomes. Point is others have done it. In the front of a Calculus book I have there is a quote; "What one fool has done, so may another". ””Yeah, I am mostly one of those fools!  And I love math!”

 

Positioners are hard to find. I have a collection amassed over the last 45 years. Was not easy to get. If you can gather the info below, you will be on the way to figuring out what to do. Ham radio guys (which I am one) do moonbounce comms which require moontracking. They have used dishes from 1 meter to 10 meters and up in diameter. Some of the homemade positioner systems are quite good and very clever. Easy = Lots of $, more elbow grease = less $. Ingenuity is king here. “The dish I acquired had a positioner screw jack on it for horizontal movement along the geosynchronous orbit to align other satellites.  But the old geezer who gave me the dish ( a longtime friend), tossed the control box when he changed to a small digital dish.  I have that hardware but not he control and voltage source for it. And of course the mfg tag is weathered beyond any recognition as to make and model so I have no idea as to even the voltage it uses. I suspect it is 12 or 24 volts DC with a switch in the control box to swap polarity on voltage so it can go either way. You have any idea as to what voltages those critters might use?  My dish is a 2.2 meter dish.  I do mine with the notion that I am saving money by building stuff on my own, a habit and it gives me some amount of happiness to build and see it work. “ 

 

First question: What is the mass and wind loading potential of the dish (static and dynamic loads)? “Well the dish was previously installed fairly locally so the mount and mast or pole are sufficient to withstand the local winds. I will be using the same hardware for the mount unless I change to alt-az type. And the dish is a mesh dish so wind can relieve itself. Two of us old geezers picked up the dish after removal from the mount and it might have weighed 25 or 30 pounds. The c-band feed horn weighs a few pounds.  My new ball bearing pillow blocks for the RA axis are good for I think 5000 pounds. Dynamic loads are slim to none. Oscillations will be small in amplitude and so the loads will be small as well. However, I have some structural dynamic software that I can and will ultimately use to analyze the vibrations etc due to positioning and wind loads.  Since it essentially worked for the sat system, I do not expect it to be changed much.  I do have a question here though: how deep should the mast or pole be set into the soil? We are not is a major freeze area and rarely ever have surface ice or frost even on the very coldest days. No water here in the desert, lol. Cold but no ice.”

 

This tells you what loads the bearings and gears/drives need to hold and survive. Fairly easy to determine based on weight and size of dish, max wind speeds in your locale. “Again, I will be using what seems to have worked for others if I can find others using the systems. I am not into reinventing the wheel. Being a test guy, I am a pretty fair structural analysist with both structures and dynamics. So all get the analysis treatment when designs are finalized.”

 

I have used beefy camera mounts with counterweights (usually necessary) for some small projects.

(Always steer to "Stow" position when done (birdbath), reduces wind loading.) A consideration not considered. Now it will be. Drift mode storage, so to speak. I would have no issue with it remaining as if in use because that is the way that sat dishes hang out. Always pointing to the target or object.

 

Second question: What readout mechanism do you need? “Ok, this is one of the major issues. But being an old engineer, I look around for stuff that can be repurposed. Like inclinometers or angle finders. Electronic. Amazon has some that are less than 30 bucks that can read degrees to 3 decimal places with some accuracy.  My plan was to use this doohickey to set the elevation manually at the vernal equinox position. Or when the RA position is mid travel. The simply move the dish manually in elevation, tighten fasteners and record angle. A recordable measurement would be fantastic but I have no idea as to what is used in the Radio Astronomy  units.  You have suggestions for both axes that can be recorded as a function of sidereal time? Or is that even the right kind of terminology? That might explain why I have issues finding stuff sometimes – wrong terminology… Suggestions? Cheap is better, lol but has to be useful as well. “

 

This will be driven by your beamwidth of the dish. If you have  a 5 degree BW dish, you do not need .001 degree accuracy, .5 degree might be sufficient and is obtainable with potentiometers/dc supplies/A/D converters (10 bit for AZ and 8 bit for EL). “I can record 16 channels of data if I get the stuff off of my race car. They have AD converter built in but probably not that accurately. I do have a desktop that can record that but some signal conditioning is going to be required to get the electrons from the measurement location, about 100 feet away to the computer. And I have quite a number of instrumentation cards for that desktop.  So, what do you suggest? “

 

Corollary: absolute or relative shaft encoding. Absolute more expensive but doesnt forget where you are when the power goes out (cheaper these days than in the past). Relative is dirt cheap, but "0" needs to be calibrated when power out.

(This question presupposes you do not use Pots, which are a very cheap form of absolute encoder.) “Encoders require electronics. More reliability issues. Pull pots and simple voltage devices and if used with a reliable power supply then likely ok at least for first light operations.  I am not taking photographs merely listening to ET phoning home.  And that signal voltage can be calibrated for pointing data as well. Other sensors can be used as well, like 3 axis solid state gyros with  integrated outputs.  Pots are ok for now and I will get busy sourcing some for my use. I do have a pair of limit switches to remove drive power when the system reaches the limits of rang of interest. “

 

Third Question: Motor drives?  DC motors are common on large pedestals and small (my camera mounts are 120V DC). 120 Volt field and armature. Easy to drive these days with H bridges and all the modern control stuff.  Steppers geared down to increase torque can be used on small stuff., relative cheap and computer controllable interface is easy. “I have several 90 volt DC motors of ½ hp but run at 1750 rpm, I also have a motor controller for those as well but only one at a time. Reasonably expensive.  I have one motor with planetary gear set on end that is about 1/3 hp and output rpm of 345 rpm max.   Open to suggestions for drives and controllers and gear boxes etc? What works for someone else will work for me as well..”

 

Anyway, this is a start. Hopefully something you can use here (hope I didnt plow ground already tilled!).  As you are no doubt aware the mechanics is troublesome. BTW, dish people do not use equatorial anymore, only did that in the early '60's when "computers do not have the horsepower to do the math!" (Ha they were wrong, by the time the 140 footer at Greenbank was done, computers had caught up!). “Old is not bad. Look at me, lol. Not everything needs to be thrown out for automation. “ 

 

Folks have used rear-ends from pickup trucks to build Az drives (needs to be the beefiest one as holds all the stuff).  El mechanics are more simple, just a knuckle and a gear, maybe even chain drive.  Old radar pedestals were used in the past, harder to find these days.  Useful for ideas through (look at the bicycle chain drive gearing of a WWII SCR-584 S band radar, should be able to find drawings on line, used bicycle gears and chains for drive, flexible coupling and gear reduction). Motorcycle chains, sprockets etc are beefy enough for most amateur needs. Backlash may be an issue but not so much if your BW is higher and you use reduction drive as well. “Interesting you should mention automotive parts.  My first iteration of the system was to use a floating axle hub from at least a one ton truck as the az mount/drive.  And a front replaceable spindle bearing mount for the el axis.  These pieces are virtually indestructible and are certainly weather resistant.   I have a 12 inch diameter pipe that was going to be my vertical mount.  Of course, the flange mount pillow blocks for the el mount is cheaper and simpler to use. No fancy machine work to install them.  You do and have hit on one of my major questions. And that is pointing accuracy.  Not sure how to determine how or what is good enough to listen to a star’s planetary system. At < 20 light years away.  I want to look at all the Keppler discoveries at that distance before moving further out.   Seems to me that if all want to do is listen for ET signals and skip the science aspect of observing, then pointing may not be so very accurate. Your thoughts?  I have and am stil considering chain drives coupled with gear boxes and variable speed motors.  Chain is rugged.”

 

If you have any questions, do not hesitate to ask. I am an old defense industry guy (microwave engineer, EW & Radar, 30 years)  who teaches at a University in Ky, We have a 21 meter dish (new) that we use for tracking and R-A. I build the receivers for it and manage it. “Sounds like you are my go to guy! I have asked a few questions that are bugging me above so take a gander and see if there is any hope for me, lol….”

 

Good luck, this is fun stuff.

Regards,

Jeff Kruth

 

“Yes, it is going to be fun, and in fact just building the stuff is fun. That was the way if was with the race car. I own a Sunbeam Tiger and I found out that Sunbeam was the very first car to set an official record over 200 mph and that was in March of 1927. No other Sunnbeam has ever gone faster than that…until me in Sept 2010. I went for a flying mile average of 204.912 mph with an exit speed of 210.779 mph but still had 600 or so ropm in the motor to go but said nope I am done, lol. Broke an 80 + year old Sunbeam record. I now have the fastest Sunbeam on planet earth. I winder if ET wodl like to know that? Maybe I’ll send them a radiogram, eh?

 

Mayf, my nickname of more than 50 years so please call me that, all my friends do.  “

 

 

 

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[Jeff Kruth]

Hey Mayf, came out green for me! I read your reply and will comment later today when I get home from work.

Regards,

Jeff Kruth

[Larry Mayfield]

Thanks, I think I have figured it out. I replied to you and there was a cc to sara lis. You got it  and the list was not in color I think. No hurry on replies I am slow worker, lol.

[Larry Mayfield]

Well, I know the message went out in color cause the guy who received it directly got what I sent. SO it has to do with the forum and Google.  Do any other messages arrive with color in them from any other source?  I think I will surf the messages and see…

[Steve Olney]

Hi Mayf,

As far as colours are concerned I see all the colours that you posted in both the received SARA email and the forum using Chrome - so, IMHO, it is not the forum or Google or chrome by my observations.

As far as Az-El drives I am no help - I wimped out with transit mode for my daily Vela pulsar observations.

Steve

[Rodney Howe]

I think this is a question for Steve, or anyone else doing pulsars: There’s a nature article this week that has this statement in it: 

The dispersive contribution arises from the signal propagating through the lens’s extra dispersion measure (electron column density) ΔDM = ∫ ne dz (with ne the (electron number density),

φDM(x, y) = −kDM/ν ΔDM(x, y) 

where kDM = e2/2πmec = 4,148.808 s pc−1 cm3 MHz2 (ref. 24). The minus sign arises because in a plasma the phase velocity is greater than the speed of light. 

24. Manchester, R. N. & Taylor, J. H. Parameters of 61 pulsars. Astrophys. Lett. 10, 67–70 (1972). 

Pulsar emission amplified and resolved by plasma lensing in an eclipsing binary robert Main et. al  https://arxiv.org/abs/1805.09348

My question is looking at the Vela pulsar there are many plasma fields in the Gum nebula. https://apod.nasa.gov/apod/ap180524.html  is it possible those ‘glitches’ could be caused by interference with plasma?? And really, is it possible to have velocities greater than the speed of light, which would cause those glitches?

Rodney

On May 29, 2018, at 2:17 PM, Steve Olney <st...@joataman.net> wrote:

[Marcus D. Leech]

On 05/29/2018 04:17 PM, Steve Olney wrote:

Hi Mayf,

As far as colours are concerned I see all the colours that you posted in both the received SARA email and the forum using Chrome - so, IMHO, it is not the forum or Google or chrome by my observations.

As far as Az-El drives I am no help - I wimped out with transit mode for my daily Vela pulsar observations.

Not "wimping out" at all.  When you have a small budget, and a fixed scientific goal, you ruthlessly discard stuff you don't need for the
  current experiment...

Steve

On 30/05/2018 5:50 AM, Larry Mayfield wrote:

Well, I know the message went out in color cause the guy who received it directly got what I sent. SO it has to do with the forum and Google.  Do any other messages arrive with color in them from any other source?  I think I will surf the messages and see…

 

mayf

[Steve Olney]

Hi Marcus,

On 30/05/2018 10:06 AM, Marcus D. Leech wrote:
> Not "wimping out" at all.  When you have a small budget, and a fixed
> scientific goal, you ruthlessly discard stuff you don't need for the
>   current experiment...

Yes - you are right - a sensible approach.  Mind you, you won't see any
close-ups of my antenna mounting efforts... (move along folks - nothing
to see here...) LOL.

Steve

[Paul Oxley]

Steve & Marcus

As I visit other SARA member's sites, I have never seen any working mechanized mounts on 1420 dishes. Rather, I see a simple mount that requires manual adjustment by releasing the azimuth and (altitude) elevation bolts. They use a compass or the Sun to set the Azimuth and a simple inclination tool (Digital or analog) to set the antenna. They use calculations of the Alt/Az at a given sidereal time to convert from the Right Ascension and Declination of the object they want to observe. Some use Jim Sky's programs for the calculation or other planetarium programs (Cartes du Ciel, Sky Charts, etc). In some cases, they even use a manual calculation or good judgement of where to point the antenna.

I have also found from experience that it is easiest to set an azimuth with a compass by back sighting toward the antenna from a point nearby the dish. If the antenna is pointed at your location, the feed will be aligned with the center of the prime focus dish. Offset feeds are more difficult where you need to depend on the offset feed mount, etc.

Paul

---

From: Steve Olney <st...@joataman.net>
To: sara...@googlegroups.com
Sent: Tuesday, May 29, 2018 9:50 PM

Subject: Re: [SARA] Re: Az-El mechanisms for dish positioner

Steve

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[Bruce & MaryRose Randall]

Dish positioning should be simple.  See Photo.

 

If you make a fancy dish positioning system, You have TWO big engineering projects instead of one to make a radio telescope.  Think like John Dobson in optical scope.

 

My normal observation is to set declination & let earth’s rotation scan sky for a week.  I usually get one day that is pretty good data in a week.

 

Bruce Randall

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[Larry Mayfield]

And why wouldn't we see your mounting efforts? Does it work? Us new folk need to see what works and how it was put into play and fabricated and anything else. My philosophy is "good enough is good enough". So shoot me some photos and what components you used and I will duplicate it for my use. Imitation is the best form of flattery, is it not? Reinventing the wheel is not doing astronomy.

Ok, enuff from me...

mayf

-----Original Message-----
From: sara...@googlegroups.com [mailto:sara...@googlegroups.com] On Behalf Of Steve Olney
Sent: Tuesday, May 29, 2018 6:51 PM
To: sara...@googlegroups.com
Subject: Re: [SARA] Re: Az-El mechanisms for dish positioner

[Larry Mayfield]

I am just trying to get started on radio astronomy. So bear with me, lol. But what is your goal or if you will, your mission statement? Why are you doing RA? Seems to me that drift scans only provide data for the very small interval of time when something is in view of the receiver. What if we (well, me) want to stay tuned to an object of interest for longer periods, Like days at a time?  I want something that can stay on target at least while the object is on my side of the planet. Then rinse and repeat for any number of days.  A fixed receiver seems antithetic to that.

 

My goal is to find intelligent signals. Artificial signals. Not of this earth, lol.  I have developed, in my mind, which some might say is vaporizing, lol, of what ET would be sending out as contact information and the manner of that signal.  MY needs are as expressed above. The ability to track specific objects one at a time for any number of sessions sufficient to provide me data for statistical analyses of the signal is a goal. I will need to code some FFT or DFT to analyse my data as well. But it is simple I think.

 

In any case, please share your successes and hows and whys with al of us.

 

Thanks for listening all yall.

 

mayf

[Dennis Farr]

I think this is like an undending search.  An RT that tracks like a computerized visual scope.

This gives some idea what is available.  Taint cheap.

https://telescopes.net/store/telescopes/telescopes/radio-astronomy/radio-telescopes.html

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[Jim Abshier]

mayf,

Most people (Hams) that do moon bounce seem to use Az/El antenna positioning systems.  I assume that this is probably because it is the easiest way to get 2-axis motion.  For your application, it might be better to try and make a polar mount that tracks in right ascension but is set manually in declination.  I have built such polar mounts in the past using TV rotators, but the antennas were rather small (about 5x5 ft). One of them even used bicycle sprockets and a chain for speed reduction. 

Jim Abshier

[Larry Mayfield]

Jim, all,

This is exactly where I am at right now.  I have modified an Orbitron TVRO dish  mount (for a 2.2 m dish) that I plan on using.   Yes, that cuts the control down to basically turning on the drive system at the proper time and with EL angle manually set.  I’ll use the SETI.net of Jims to figure out the times etc for the stars systems I want to observe.  I have considered chain and sprockets, compound worm gear set ups etc. and am currently building a tool for my lathe to cut 360 tooth worm wheels.  I have a cutter for use if I decide to use 180 tooth worm wheel and change the input drive by an additional factor of 2 to maintain the same clock speed for the RA axis.  The dish and its mount will be fully weight balanced to reduce the drive loads and for easy repositioning.  I may use a stepper motor to drive everything but as yet have not made that decision.

 

Thanks for listening!!

 

mayf

[Larry Mayfield]

Dennis, I agree. But there are people who have dome the impossible and yet seem reluctant to share the actual designs with others. Is it a commercial potential issue  or what,   wonder.

I hope that the below will illustrate one of the things I think could be done. From the link below as an example only!

 

This is a perfect example of everything that is needed for radio telescope alt-az mount, control and drive systems.  I think it is possible to purchase everything in the photo that is drive and control as replacement parts or repair parts. Certainly I would not need the optics, or tripod and related stuff. I would remove the encoding systems, and mount them on the larger dish  for both az and alt axes.  Scale up of drive motors might be needed but I suspect that Celestron has drives for larger optics. This then would contain all the go to elements, the positioning and anything else including software to make it go for a  few bucks (figuratively speaking, lol).  I would; be basically scaling this mount up to my dish size; might not look the same but function the same general way.  Electronics won’t care what they are hooked to.  My az mount would be fabricated from either a semi trailer axle stub or a 1 ton truck rear axle floating axle hub.  That would provide the capacity to carry just about anything that could be bolted to the hub wheel flange. A fabricated tripod or pier (oh, hell, mast), used or a single post to hold it in place. A simple fork to hold the dish.  But with the alt drive part included.

 

Use of a system like this would eliminate a lot of prep work and design to the minimum needed to get up and running.

 

mayf

 

 

From: sara...@googlegroups.com [mailto:sara...@googlegroups.com] On Behalf Of Dennis Farr
Sent: Wednesday, May 30, 2018 7:07 AM
To: Society of Amateur Radio Astronomers <sara...@googlegroups.com>
Subject: Re: [SARA] Re: Az-El mechanisms for dish positioner

 

I think this is like an undending search.  An RT that tracks like a computerized visual scope.

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[Wolfgang Herrmann]

Hi Paul and others,

I think there are quite a few mechanized mounts for 1420 dishes. Putting aside our big 25m dish which is fully steerable we also have a 3m dish with a Alt/Az mount which is capable to tracking celestial objects under computer control. Admittedly, we have not yet published much about it. But I will write a comprehensive article for the SARA journal in the coming months describing the design and observation results. Please bear with me until I have finished writing things up.

Other than that, here just a few steerable dishes from amateurs:

Jean-Jaques setup: http://f1ehn.pagesperso-orange.fr/fr/f_radioastro.htm

Tadeja Saje and Matjaz Vidmar: http://antena.fe.uni-lj.si/literatura/Razno/Diplome/Radioteleskop/clanek/radioteleskop.pdf

A polar mount version: http://www.germersogorb.de/html/radioastronomie.html

I think there are plenty of other examples of steerable dishes of various sizes.

When it comes to converting right ascension and declination to the azimuth and elevation for your location and the current time, there are various tools. For new designs there is the very comprehensive astropy package. This has now incorporated the previous pyephem package which you could use if you only want the coordinate conversion. At our site, we also use the somewhat outdated pytpm package. All these are Python based.

 

Cheers

Wolfgang

 

---

Von: sara...@googlegroups.com [mailto:sara...@googlegroups.com] Im Auftrag von Paul Oxley
Gesendet: Mittwoch, 30. Mai 2018 04:12
An: sara...@googlegroups.com
Betreff: Re: [SARA] Re: Az-El mechanisms for dish positioner

 

Steve & Marcus

 

As I visit other SARA member's sites, I have never seen any working mechanized mounts on 1420 dishes. Rather, I see a simple mount that requires manual adjustment by releasing the azimuth and (altitude) elevation bolts. They use a compass or the Sun to set the Azimuth and a simple inclination tool (Digital or analog) to set the antenna. They use calculations of the Alt/Az at a given sidereal time to convert from the Right Ascension and Declination of the object they want to observe. Some use Jim Sky's programs for the calculation or other planetarium programs (Cartes du Ciel, Sky Charts, etc). In some cases, they even use a manual calculation or good judgement of where to point the antenna.

 

I have also found from experience that it is easiest to set an azimuth with a compass by back sighting toward the antenna from a point nearby the dish. If the antenna is pointed at your location, the feed will be aligned with the center of the prime focus dish. Offset feeds are more difficult where you need to depend on the offset feed mount, etc.

 

Paul

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[Steve Olney]

Hi Mayf,

On 30/05/2018 11:34 PM, Larry Mayfield wrote:
> And why wouldn't we see your mounting efforts? Does it work? Us new folk need to see what works and how it was put into play and fabricated and anything else. My philosophy is "good enough is good enough". So shoot me some photos and what components you used and I will duplicate it for my use. Imitation is the best form of flattery, is it not? Reinventing the wheel is not doing astronomy.

Firstly, I think Marcus nicely summarises my situation...

> When you have a small budget, and a fixed
> scientific goal, you ruthlessly discard stuff you don't need for the
> current experiment...

...where I had a single target purpose - to observe the Vela pulsar. 
After spending some years educating myself to the requirements to
achieve that target within the constraints imposed (budget, location,
skill set, tools available, etc) I settled on a fixed mount which stays
locked to a particular Az-El pointing.  I think details of a fixed mount
is not particularly useful to others other than to say "I use a fixed
mount".

Secondly, at HawkRAO I only have a small window on the sky due to
extensive tree coverage on the 3/4 acre block.  As the 3 dB beamwidth of
the antenna used (19 dBi @ 436 MHz) is ~21 degrees (which translates
into about 2 hours of fixed position transit time for -45 degrees DEC),
I only have about 20 degrees of movement along the -45 degrees
declination arc before trees enter the beamwidth - which would gain
about another 1.5 hours of observation time (~ 1.2 dB S/N gain).  Given
one of the other goals of the project was daily automated observations
for periods up to 3 to 4 years, the cost of a moveable mount in terms of
financial and reliability factors associated with adding tracking to a 6
m long Yagi pointing almost straight up, for such a small gain, was
deemed not attractive in terms of cost/benefit to me at this location.

So, I have a fixed mount of simple construction consisting of a treated
pine pole, a non-metallic support strut made of concentric PVC pipe and
a piece of chain to lock it in elevation.  Hence...

> Mind you, you won't see any close-ups of my antenna mounting efforts... (move along folks - nothing to see here...)

...a view of which can be seen here...

http://hawkrao.joataman.net/pulsar/system_design/index.html

...while some details of mounting a movable (but not tracking) dish for
H1 observations from an earlier project can be seen here...

http://hawkrao.joataman.net/H1/system_design/

I hope this helps.

Cheers

Steve

[Larry Mayfield]

Indeed it does, it clears up the fixed mount to observe your target. Obstacles in the way. I have mountains which will limit some of my viewing time somewhat. And a big shop right in the way of low hanging southern sky objects so to speak.

Many thanks for clearing it up for me! And yes, I fit into Marcus' words as well. I try and make do with what I can find and modify or repurpose as well.

mayf

-----Original Message-----
From: sara...@googlegroups.com [mailto:sara...@googlegroups.com] On Behalf Of Steve Olney
Sent: Wednesday, May 30, 2018 1:43 PM
To: sara...@googlegroups.com
Subject: Re: [SARA] Re: Az-El mechanisms for dish positioner