Hy-Gain HDR-300A Conversion, pt3

I made a little more headway on the rotator controller conversion... The rear panel conne lions are finished, I painted the front panel to cover the 0-180° dish markings, installed a run capacitor across the CW and CCW winding connections, and finished the repairs and paint on the cover. I was finally able to test the motor control, and get the position display calibrated a bit closer. Here's a few pics and a video...

Hy-Gain HDR-300A Conversion, pt2

 The previous blog demonstrated the ability of this satellite dish elevation controller to be converted to a 360° azimuth rotator controller. 

I mapped the HDR-300A wiring to the rear receptacle, changed the receptacle to screw-type terminal strips, installed a pot for "zero" calibration, and tested this setup on another HD-73 rotator motor. So far, so good! Here's a few pics and video...

First, I mapped the various terminals and their function...

Here, I made a chart of the internal wiring colors to the output connector, and their function.

I installed a 300 ohm pot for "zero" position calibration...

Down below is the output connector location, when it was removed.

I installed to terminal blocks...a small block for feedback pot connections, and a larger block for the higher current motor and brake connections.

I mapped the original Alliance rotor controller connections and their motor functions.

More mapping the old vs. new controller cross reference...

Feedback pot not yet connected, while sorting the motor control functions.

The gearmotor and feedback pot assy from the Alliance HD-73 antenna rotator.

The motor run capacitor that must be used, the HyGain controller originally connected to a basic ac motor that required no capacitor.

Hy-Gain HDR-300A Conversion, pt1

This was is an old Hy-Gain HDR-300A 180° satellite elevation positioner I got from a friend. It was kinda cool looking, and I wondered if I could mod it to use as a conventional 360° azimuth controller for my tower mounted antenna stack and HD-73 antenna rotator. It was kinda beat up, the bottom was damaged from being dropped (it has a large transformer and is kinda heavy), the case was scraped and scratched, and it was pretty dirty.

The most important step was to see if it could be modded for 360 operation, and be interfaced with the 75 ohm feedback pot in my HD-73 rotator assembly. 

Here's a few  pics and video...

I used external pots to simulate my 75 ohm rotator feedback pot. This unit places 5vdc across the rotator feedback pot, and looks for a 0-5vdc return signal to translate to 0-180° of movement. Calibration would allow for a negative position of -90ish degrees, instead of displaying a positive declining value of 359° or less, when rotated below North via West. However, I could change range on the digital converter, and display to over 600° positive. I decided to set the controller up to rotate North to North to manage this issue, as opposed to South to South as in most typical rotator controllers. 

Once I settled on the rotator stop point as being North (0 degrees), I calibrated the digital display to range from 0 to 360 degrees (0 to 5 volts in). I did, however, need a variable 0-300 ohm pot to tweak the 0° reading when the rotator was at North via East (full ccw). Once that was done, it displayed properly and was amazingly linear! Above is my chicken scratch drawing of the electrical mods to the display circuit...

More on the conversion in the next post...

More tower work, 7/18/17

Well, this is sorta tower work... I decided to get some of the bugs worked out of my top tower section, before hauling it all up to the 100' point. The previous blog described the issues with the thrust bearing, rotator shelf, and mast position. With all of that out of the way, I moved on to a setup and dry run prior to installation...

I installed the rotator and got it in position, slipped the mast into the thrust bearing, set the height of the mast, installed a mechanical stop on the mast so the thrust bearing would support the weight of the antennas (instead of the weight bearing down on the rotator), and installed a new set of torque arms  my dad gave me. I also have a new upper skirt my dad made, to shed the water from the thrust bearing, once installed. Here's a few pics...

Rotator connected to the controller, and a few test runs made to make sure it turns without any binding. All is well, and ready for action!

 

 Rotator alignment completed, with no issues in rotation. I can't wait to get this beast up on the tower!

Mast centered in the thrust bearing. The thrust bearing is now pumped full of fresh grease, and turning smoothly. Dad fabricated a new skirt for a water shed to install here...

 The mast sits about 1" off of the rotator housing, so as to not present any vertical load. 

 Dad gave me a set of torque arms he had stashed away for Rohn 25! Yes! This thing has always twisted when I would start or stop the rotation of the stack, this should solve that problem!

 Torque arms installed and ready for connection to the guy wires!

Can't wait to get this hoisted upon the tower to the top, and get my guy cables connected!!

Dave WB4IUY
http://www.WB4IUY.net

More Tower Work, July 8 & 9...

Wow, this was a busy "tower work weekend". The temp were in the low 90's with high humidity, so we started early. First thing, I helped a friend take down his 48' Rohn 25 tower, in preparation for a move to his new home. Ken had already removed his antennas and dropped the guy cables (he had a Hazer on it!), so it came down fast. In less than 2 hours, it was laying on the ground and ready to haul away.

Before....

After, in under 2 hours!

I returned to my QTH and climbed to the top of the 90' section on my tower, relocating the gin pole from 80' to 90', in preparation for pulling up the next section. I've decided to put the top on it here, and stop the tower at 100'. There will be 15' of mast above that, with a 21' vertical antenna mounted on top of the mast...that'll put the tip top of my stuff at 136'. I'm already on a hilltop, located at 375' ASL, and the nearly identical setup has worked very well for me over the last 24 years. 

 Gin pole moved to 90' and extended to over 100', ready for the next section of tower...

I needed to do a bit of preparation and a few mods to the top section, to remedy problems I've had in the past. I cleaned the grease fitting on the thrust bearing and lubricated it well. It seemed to be dry, but then, it has been in the weather and in operation many years. The pinch bolts in the collar of the thrust bearing needed attention, as one had become loosened and fallen out somewhere along the years, shifting all of the vertical load directly onto the rotator. 

Thrust bearing on the top...new allen screws installed for centering the mast in the bearing...

Mast guide plate, mid-section...

Next, the lower rotator shelf has always been a problem, requiring the rotator to be left slightly loose on the shelf due to an alignment issue. It was pre-drilled when I got it (don't remember where it came from), and I found it was off about 1/4"! Whew... I marked the plate and slotted it with my old manual mill to allow for perfect alignment when it is reinstalled.

 Rotor shelf marked up to determine the error and corrections needed...

 Rotor shelf clamped down on the table of my old manual mill...

Slotting the rotor bolt holes to allow for accurate alignment of rotor, once installed in the tower...

The rotator is an old Alliance HD-73, and has served me well all these years. It's had a rough life, being operated severely overloaded for turning load, as well as having supported a tremendous amount of weight. Rotation, lock to lock, was generally on the order of 80 seconds. It was welded together once by a lightning strike, and I literally broke it loose with a hammer and never removed it for service...about 19 years ago!  Never-the-less, it has performed well. When the storm destroyed the tower back in April of 2016, it was stuck upside down in a tree for about a month, until we could get a crane to get it down. During that time it rained inside of the rotator, which certainly did it no good. I pulled it apart today, cleaned out all of the rust, wire brushed all of the moving parts and all 4 of the bearing races, cleaned and packed all of the 104 individual ball bearings, reassembled it, gave it a good cleaning and a coat of paint. A quick test found it working like new and ready for action. 

I had to use the Dremel tool and a cut-off disk to deepen the slots of the screw heads, so they could be removed from the terminal strip where the rotor cable connects. Lots of rust...

 Loads of rust on the terminal strip...

Corrosion on the bottom of the housing was so bad, it looked as if the bottom of the rotor has been hammered in... I cleaned it off with a wire brush, and it got a heavy coat of paint later... 

Terminal strip cleaned with a small sanding wheel...

New screws installed in the terminal strip...

Rotor, after disassembly, internal cleaning and lubrication, and re-assembly...

I gave it a "road test", a fresh coat of paint, and she's ready for action!

That was all I could do today, and tomorrow is another work day. More work coming soon, the tower top will be headed up to the 100' point in a few days!

Dave WB4IUY
http://www.WB4IUY.net

HD-73 rotor or motor needed...

On the morning of 8/24/13, the motor in my Alliance HD-73 antenna rotator failed. A few tests found the motor windings to be shorted to the housing. It's been a great antenna rotor, providing 20 years of service though hurricanes, ice, rain, etc. It even survived a lightning strike back in '98! Since my rotor mount base plate is drilled for this unit, my thrust bearing is pinned for the height of the housing, etc, I'd rather repair this unit than have to refit everything for a rotor of a different manufacture or model.

If anyone has a junked HD-73 rotor with bad gears, bad feedback pot, cracked housing, etc, I'd love to buy this from you. I'm only looking for a motor. Otherwise, if you have a complete HD-73 rotator unit for sale, I'd like to speak with you as well. Please email me at wb4iuy@eastrc.org with your info. Thanks!

Dave WB4IUY
www.WB4IUY.net
wb4iuy@gmail.com

Light Duty Rotator? No problem!

I was listening to a conversation on HF between two guys who each had spent well over $1000 for antenna rotators, each having less rotator load than myself. I joined into the conversation and both guys quickly told me how I was doing this wrong, why I was doing this wrong, and how my rotator would never hold up the way I have it loaded. So, I'm typing in my blog pretty much what I told them... Suffice it to say I'm cheap when it comes to this hobby. I've been a ham since 1974, and most everything I've had, I've bought used, as junk or "fixer uppers", or built. There is only one rig in my shack I've bought new... Back in 1993, I had my doubts about using a light duty rotator to turn my array. I'd been picking up pieces of salvage or used Rohn 25 & other parts for a couple of years to build my tower, and only had about $300 total in my 105' tall tower setup. I had a big pile of aluminum I had collected from swap meets, salvage from another ham's hurricane damage, and stuff I'd accumulated from helping other folks with their tower setups (read $0 investment). The rotating mass consisted of a Cushcraft A3S, a 5el 6m Cushcraft yagi, 2ea. Cushcraft 17b3 long boom yagis for 2m, and a 15' tall Diamond vertical on top. The problem was, a rotator for this much stuff was gonna cost more than I had in everything else combined, and was way out of my budget. After pondering it a bit, I remembered an experiment I had with an old TV antenna rotator many years ago. I discovered that most of the small rotators use a shaded pole motor (similar in design to that used in small fans and such). Shaded pole motors are neat in that they don't really overheat or fail when overloaded or stalled. I found that if I fed the small TV rotator with a long run of a small gauge rotator cable, there was sufficient voltage drop across the cable when the rotator was stalled to prevent the rotator from overheating. I visited a local radio shop and found a HD-73 rotator by Alliance. This is a very light duty rotator, but unlike some of the cheap TV antenna rotators, it had a feedback pot in the rotator housing for position indication on the control box. So, even if it was slow, the indicator would still display the direction accurately. Many TV antenna rotators have a separate motor that turns the indicator on the control unit and they easily get out of sync if the rotator stalls. A feedback pot is the only way to go...

I made a tower mount for it, installed a bearing around the vertical mast with a home made ice shield, and installed it. Once everything was stacked on top, it was time for the real test. In June of 1993, I found that it took about 75 seconds to turn from stop to stop. As of this writing, 19 years later, it still takes about 75 seconds to make the journey from south to south. It has survived a direct lightning strike that welded the bearings together. I've worn out the direction control switch on the unit and had to replace it. It has been stalled when I'd forget and leave the control box rotating in one direction or another (it is no longer 'spring return' to the OFF position), to the point where the thermal sensor in the control unit would trip. It has run flawlessly while horribly overloaded for 19 years. I've learned that cheap can often be shoe-horned into operation and work pretty good, a little planning makes 'cheap' work a long time, and the HD-73 has got to be tough WAY beyond it's price point!