Can I use the Yaesu G-5500DC antenna rotator to point a dish at a specific object in the night sky and track it? Could this be used to detect and follow masers?

ADVICE FROM CHATGPT (NO PROMISES MADE ABOUT HOW EFFECTIVE THIS ADVICE IS):

Best value source for Yaesu G-5500DC antenna rotator and computer controller in the UK:

If your goal is the best value (not simply the lowest price), I’d currently shortlist these options:

Best overall value

The strongest UK deal I found is the Yaesu G-5500DC from ML&S at about £650.

For computer control, the traditional Yaesu interface is:

• — around £420 from ML&S.

If by computer controller you mean the S.A.T. / CSN controller

Many satellite operators are now using modern third-party controllers such as the CSN SAT Controller rather than the older GS-232B interface. Recent amateur-radio discussions indicate that the CSN SAT controller has become a popular choice for G-5500 installations.

If that’s the controller you mean, tell me the exact manufacturer or model number (S.A.D., SAT, CSN, Green Heron, etc.) and I’ll search current UK and EU stockists.

Comparison

For a complete satellite station, I would currently buy the G-5500DC from ML&S/Ham Radio and then decide whether you need the GS-232B or a newer controller solution. The G-5500DC itself remains one of the most widely used and cost-effective AZ/EL rotators for amateur satellite work.

Could you confirm exactly which “SAD controller” you mean? There are several similarly named rotor controllers in the satellite community, and I can then find the cheapest current supplier in the UK or Europe.

I would like to use the YAESU G-5500DC with Stellarium planetarium software. How do I do that?

The important thing to know is that Stellarium cannot directly control a Yaesu G-5500DC rotor. The G-5500DC is a rotator/controller, not a computer-controlled mount. You need an intermediate controller that speaks a standard rotor protocol such as Yaesu GS-232.

A typical setup is:

Stellarium
    |
    | (Telescope Control plugin)
    |
Hamlib / rotctld
    |
GS-232A / GS-232B compatible controller
    |
Yaesu G-5500DC
    |
Azimuth + Elevation rotators

Option 1 – Official Yaesu method

Use a:

• Yaesu GS-232B

Connect the GS-232B to the G-5500DC controller’s external control port and then connect the GS-232B to the PC via RS-232 (or a USB-serial adapter). The G-5500DC manual specifically references the optional GS-232 computer interface.

Option 2 – Modern and cheaper method

Many satellite operators now use:

• K3NG Arduino rotor controller
• SatNOGS rotor controller
• CSN SAT Controller

These emulate the GS-232 protocol and work with Hamlib. The SatNOGS project specifically notes support for Yaesu GS-232 compatible controllers and the G-5500.

Configuring Stellarium

Install:

1. Stellarium
2. Hamlib
3. rotctld (Hamlib rotor daemon)

Start rotctld using the GS-232 model.

For example under Linux:

rotctld -m 603 -r /dev/ttyUSB0 -s 9600

(Exact model number may vary slightly depending on Hamlib version and whether you’re using a GS-232A or GS-232B compatible controller.) Amateur satellite operators commonly use this approach with G-5500 systems.

Then in Stellarium:

1. Enable Telescope Control plugin.
2. Add a new telescope.
3. Select External software or networked telescope.
4. Connect to localhost (127.0.0.1) and the TCP port used by rotctld.
5. Stellarium can then display and control the pointing position through Hamlib. The Telescope Control plugin is designed to communicate with external control software and mounts.

For satellite tracking

For amateur satellites, most operators actually use:

to drive the rotor, while Stellarium is used only as a sky display. GPredict and SatDump both interface well with Hamlib and rotor controllers.

What I would recommend for your radio astronomy setup

Since you’re already working with SDR systems and Linux, I’d skip the expensive GS-232B and use:

1. G-5500DC
2. K3NG Arduino rotor controller (GS-232 emulation)
3. Hamlib/rotctld
4. Stellarium and/or GPredict

That gives full computer control, satellite tracking, and future integration with your SDRplay and GNU Radio systems at much lower cost.

If you’re planning to use this specifically for a satellite Yagi array (e.g., NOAA, Meteor, QO-100, AO-7, ISS, etc.), .

Source of ARS-Shield – EA4TX.com:

If I go with following where is best place to get them: G-5500DC K3NG Arduino rotor controller (GS-232 emulation) Hamlib/rotctld Stellarium and/or GPredict.

For your intended setup, I’d buy only the hardware and download the software free.

Recommended shopping list

G-5500DC

My first choice would be:

• from ML&S.

Although an eBay listing appears cheaper, a rotator is a long-term investment and dealer support matters when you’re installing an Az/El system on a mast or tower. The current UK dealer price is about £650.

K3NG Controller

You have three realistic choices:

1. Build from scratch
   • Arduino Mega
   • Relay board
   • Position sensing interface
   • K3NG firmware
2. EA4TX ARS-Shield
   • Designed specifically for K3NG firmware.
   • Available as PCB or PCB plus enclosure.
3. Commercial controller
   • microHAM ARCO
   • Much more expensive but turnkey.

For someone with your technical background, I would strongly lean toward the EA4TX/K3NG route.

Hamlib

Official project:

• Hamlib rotor daemon (rotctld)
• Supports GS-232 emulation used by K3NG.

On Ubuntu:

sudo apt install hamlib-utils

Stellarium

Official website:

Install the Telescope Control plugin and connect it to rotctld.

GPredict

Official website:

Many satellite operators actually run:

GPredict
   |
rotctld
   |
K3NG Controller
   |
G-5500DC

with Stellarium simply displaying the sky.

What I would buy today

1. G-5500DC from ML&S.
2. Arduino Mega 2560.
3. EA4TX ARS-Shield.
4. Hamlib.
5. GPredict.
6. Stellarium.

That gives you a complete computer-controlled Az/El system for satellite tracking and would also integrate nicely with your SDRplay-based observing projects. The total cost is typically several hundred pounds less than buying a GS-232B interface.

If I instead used yaesu gs-232b, could I then control the rotator and point to specific objects in sky and track it.

Yes — with some important limitations.

The GS-232B can provide computer control of a Yaesu G-5500DC, allowing software to command azimuth and elevation positions. However, whether you can “point at an object and track it” depends on the type of object.

What works well

Satellites

This is exactly what the G-5500DC + GS-232B combination was designed for.

Software such as:

• GPredict
• SatPC32
• Nova for Windows

can calculate the satellite’s position continuously and send updated azimuth/elevation commands through the GS-232B. The antenna automatically follows the satellite across the sky.

The Sun

You can track the Sun because its position changes predictably and software can continuously update the rotor position.

The Moon

Likewise, the Moon can be tracked automatically.

What is more difficult

Stars, galaxies, nebulae, planets

A rotor only provides:

• Azimuth
• Elevation

It does not provide the equivalent of an astronomical equatorial mount with sidereal tracking.

For radio astronomy this is often fine because:

• Your antenna beamwidth may be several degrees wide.
• The object drifts slowly.
• Software can periodically update the rotor position.

For example, tracking:

• Andromeda Galaxy
• Cygnus A
• Cassiopeia A

is feasible if software continually computes the changing azimuth and elevation and sends commands via the GS-232B.

Using Stellarium

Stellarium knows the coordinates of many celestial objects.

In principle:

Stellarium
    |
GS-232 compatible interface
    |
GS-232B
    |
G-5500DC

allows you to click an object and slew the antenna to its current azimuth/elevation.

The challenge is that Stellarium’s telescope control is primarily designed for telescope mounts, so many radio amateurs instead use:

Stellarium (display)
GPredict or custom software (control)
GS-232B
G-5500DC

For your radio astronomy

Suppose you have a 1420 MHz Yagi or horn and want to observe:

• Sun
• Cygnus A
• Cassiopeia A
• Sagittarius A*

A PC can calculate the object’s azimuth/elevation every few seconds and send commands through the GS-232B to keep the antenna pointed correctly.

My recommendation

For a radio astronomy station, the GS-232B is convenient but expensive. A modern GS-232-compatible controller (such as a K3NG-based unit) gives essentially the same functionality.

If budget is not a concern and you want a proven commercial solution with minimal construction work:

G-5500DC + GS-232B + Stellarium + Hamlib is a solid combination and can point at and track satellites, the Sun, the Moon, and fixed celestial radio sources by continuously updating the antenna position.

What is best choice for maser observing?

For observing astronomical masers (especially the 22.235 GHz water maser line), the “best” choice depends heavily on the size and beamwidth of your antenna.

If you are using a dish at 22 GHz

A dish of 1-3 metres at 22 GHz has a relatively narrow beam, so accurate pointing becomes important.

In that case, I’d recommend:

1. Yaesu G-5500DC
2. Yaesu GS-232B or a K3NG-compatible controller
3. Hamlib/rotctld
4. Custom astronomical tracking software

This allows automatic tracking of maser sources such as:

• Orion KL
• W3(OH)
• W49N

As Earth rotates, the software continuously updates azimuth and elevation.

If you are using a small dish (under about 1.2 m)

The beamwidth is wider and tracking accuracy is less critical. A G-5500DC alone is usually sufficient.

If you are using a larger dish (2-5 m)

I would lean toward a higher-performance astronomical mount rather than a G-5500DC because:

• Less backlash
• Better position accuracy
• Better repeatability
• Smoother tracking

Many serious amateur maser observers use surplus satellite-communication dishes with industrial positioners rather than amateur-radio rotators.

For your situation

Given your radio astronomy interests and previous work around 1420 MHz, if you’re planning to move into 22 GHz water masers with a dish around 1-2 m diameter, I would choose:

Dish (1–2 m)
    |
G-5500DC
    |
GS-232B or K3NG controller
    |
Hamlib
    |
Tracking software

The deciding factor is beamwidth. For example:

At 22 GHz, cm.

Approximate half-power beamwidths are:

A G-5500DC can comfortably keep a 1-2 m dish on target. Once you get to 3 m and above, pointing accuracy becomes much more demanding and many observers move to industrial positioners.

For a first water-maser system, a 1.2-1.8 m dish on a G-5500DC with GS-232B/K3NG control is a very practical and widely used approach.

K3NG Controller:

The K3NG Arduino Rotator Controller

There is a Yaesu GS-232B clone on Aliexpress for £123. Would this work with G5500DC to point at and track masers with 1-2m size dish and how would I do it?

Yes, many GS-232B clones from AliExpress do work with the G-5500DC, because they simply emulate the Yaesu GS-232B command set and generate the same control voltages/signals expected by the rotator controller. However, there are two caveats:

1. Build quality varies considerably.
2. Some clones support only a subset of GS-232B commands, so it’s worth checking whether users have successfully used the specific model with Hamlib or satellite-tracking software.

For maser observing with a 1–2 m dish, the pointing requirements are not especially demanding:

• 1 m dish at 22 GHz: beamwidth about 0.9°
• 1.8 m dish at 22 GHz: beamwidth about 0.5°
• G-5500DC pointing accuracy is typically adequate for this application if properly calibrated.
• Water masers are usually observed as fixed celestial sources, so tracking rates are slow and smooth compared with satellite tracking.

How the system would work

PC
 |
 | USB
 |
GS-232B clone
 |
 | Control cable
 |
G-5500DC
 |
Dish

Software calculates the current azimuth and elevation of the maser source and sends commands to the GS-232B clone, which moves the G-5500DC.

The software side

The easiest route is:

1. Install Hamlib.
2. Connect the GS-232B clone via USB.
3. Run rotctld.
4. Use software that can drive Hamlib.

For example:

Planetarium / Tracking Software
          |
       Hamlib
          |
      rotctld
          |
   GS-232B clone
          |
      G-5500DC

Pointing at a maser source

Suppose you want to observe:

• Orion KL

The source has fixed celestial coordinates (RA/Dec).

Tracking software converts those coordinates into the current azimuth and elevation for your location in Staffordshire and continuously updates the rotor.

You can:

• Click the source in a planetarium program.
• Select it from a catalogue.
• Enter the RA/Dec manually.

The software then keeps the antenna pointed at it as Earth rotates.

Software options

Option 1: Stellarium + external rotor control

Stellarium can display the source position, but rotor support for radio astronomy is somewhat limited.

Option 2: Custom Python script (recommended)

Many radio astronomers use:

• Hamlib
• Astropy

A Python script can:

1. Read the maser’s RA/Dec.
2. Calculate current Az/El.
3. Send GS-232B commands through Hamlib every few seconds.

This is quite straightforward and gives excellent control.

Option 3: Cartes du Ciel

Cartes du Ciel has better support for external telescope and mount control than Stellarium and is often used by amateur observatories.

Would the AliExpress clone be accurate enough?

For a 1–2 m dish at 22 GHz:

Almost certainly yes, provided:

• The clone correctly implements GS-232B commands.
• The G-5500DC is calibrated.
• The mast is vertical.
• Rotor backlash is minimized.

The dominant pointing errors are usually mechanical installation errors rather than the GS-232B interface itself.

What I would do

If the clone has good reviews and explicit GS-232B compatibility:

• Buy the G-5500DC.
• Buy the £123 GS-232B clone.
• Install Hamlib on a Linux PC.
• Use a small Astropy-based tracking program to follow masers automatically.

That would be a cost-effective setup for a 1–2 m 22 GHz water-maser dish and should provide all the pointing accuracy you need. If you have a link to the specific AliExpress clone, I can assess whether it appears to be a full GS-232B implementation and whether others have reported success with Hamlib.

I asked ChatGPT about the clone link below:

https://www.aliexpress.com/item/1005004763708095.html?invitationCode=SW53UXJNNDFPaUg3QmNSQmxQTS9DNTZSOWhlWHREMUpzM1NTVGFKTlo5ST0&srcSns=sns_Copy&spreadType=socialShare&social_params=61535480969&bizType=ProductDetail&spreadCode=SW53UXJNNDFPaUg3QmNSQmxQTS9DNTZSOWhlWHREMUpzM1NTVGFKTlo5ST0&aff_fcid=363ee390e4be4acb8ecf776976499c61-1780863844662-04642-_EGZhv2O&tt=MG&aff_fsk=_EGZhv2O&aff_platform=default&sk=_EGZhv2O&aff_trace_key=363ee390e4be4acb8ecf776976499c61-1780863844662-04642-_EGZhv2O&shareId=61535480969&businessType=ProductDetail&platform=AE&terminal_id=f146b91e97794002ac25fbd267e632a9&afSmartRedirect=y

ChatGPT response 7/6/2026:

From the URL and the matching products I found, this appears to be one of the common USB-232B / GS-232B-compatible interface boards rather than a genuine Yaesu GS-232B. Similar units are sold for about £125–130 and specifically claim compatibility with the G-5500.

My assessment

For maser observing with a 1–2 m dish, I’d be willing to try it.

Reasons:

• The GS-232B protocol is well documented.
• These clones are widely used with rotor-control software such as Orbitron, HRD, Hamlib and GPredict.
• The pointing accuracy of your system will be dominated by:
  • mast alignment,
  • rotor calibration,
  • dish mounting geometry,
  • backlash,
  not by whether the controller is a £123 clone or a £500 Yaesu unit.

Possible downside

The main risk is not pointing accuracy but compatibility and setup headaches.

There are reports from users running cheap GS-232B clones with G-5500 systems who encountered:

• scaling issues,
• incorrect angle reporting,
• serial communication problems,
• Hamlib configuration issues.

These are usually solvable but may require tinkering.

How I would set it up

22 GHz dish (1–2 m)
        |
     G-5500DC
        |
GS-232B clone
        |
 USB
        |
 Linux PC
        |
   Hamlib rotctld
        |
 Astropy tracking script

Tracking a water maser

Suppose you want to observe:

• Orion KL

The software would:

1. Store Orion KL’s RA and Dec.
2. Convert them to Az/El for Lichfield every few seconds.
3. Send GS-232B commands through Hamlib.
4. The G-5500DC moves automatically.

For example:

rotctld -m 603 -r /dev/ttyUSB0 -s 9600

The GS-232B model used by Hamlib is typically model 603. Users have successfully used this arrangement with G-5500 systems.

What I would buy

My recommendation

If the clone is genuinely around £123 delivered, I’d buy it and test it before spending £420–500 on a genuine GS-232B. The cost difference is large enough that even if you later upgraded to the official unit, the experiment would be worthwhile.

The one thing I’d suggest before ordering the G-5500DC is sending me a screenshot of the clone’s rear-panel connectors and included cables. I can then verify whether it includes the 8-pin DIN cable required for the G-5500DC AZ/EL controller, which is the detail most likely to determine whether it will be plug-and-play.