Saellite Tracker Jr.

Satellite Tracker Jr.

The Satellite Tracker JR. is a new interface, aimed at the barbecue grill dishes and other small dishes along with small to medium sized yagis on Yaesu G-5400, G-5600 or G-5500 rotators market. This unit is designed to be as low cost as possible, yet offer features never before seen by the satellite chasing fraternity. When the Yaesu rotator control box is turned on, the Satellite Tracker Jr's LCD identifies and shows the internal setting.

Satellite Tracker Jr controlling a Yaesu G-5400 Satellite Tracker Jr controlling a Yaesu G-5500

In manual mode, this interface plugs into the 8 pin DIN connector on the back of a Yaesu G-5400, G-5600, or G-5500 rotator's control unit. One switch of an 8 bit dipswitch selects whether a Yaesu G-5400 or G-5600 (360 degrees azimuth, N centered) or a Yaesu G-5500 (450 degrees azimuth, S centered) is being used. The 8 pin DIN connector provides power and analog voltages proportional to the azimuth and elevation position of the rotators. The interface provides a large digital display of the Yaesu rotator's elevation and azimuth position, accurate to 1 degree, far more accurate than the analog azimuth and elevation meters on the Yaesu controller.

In automatic mode, besides being plugged into the Yaesu rotator's controller, the Satellite Tracker Jr. is also plugged into a COM port of a computer running a satellite tracking program. The computer sends azimuth and elevation to the interface, and the interface takes over control of the Yaesu rotator's control unit, activating the up, down, right or left circuitry in the Yaesu controller in response to desired azimuth and elevation coordinates. The Satellite Tracker Jr. is also provides variable speed movement of the Yaesu azimuth and elevation motors. Two switches of the 8 bit dipswitch select 4 different azimuth dead zones; another 2 switches select 4 different elevation dead zones; and another 2 switches let the user select the desired variable motion. Dead zone width prevents endless position seeking of a rotator. But too much width leads to inaccuracy, very undesirable when aiming a narrow beamwidth dish. When repositioning the antennas to track a different satellite, you want the antennas to move quickly. But when you are getting close to the satellite, the Satellite Tracker Jr. reduces the speed of the rotator to avoid overshoot and subsequent oscillation. While tracking the satellite, especially the Low Earth Orbiting ones (LEOs), the movement will usually be at the slow rate, providing a very smooth motion without rotator destroying oscillation, especially with long yagis. Should the tracking start to fall behind, the Satellite Tracker Jr. automatically shifts to high speed to catch up, then returns to the lower pace.

The automatic mode requires data over an RS-232 line operating at 9600 baud. The azimuth and elevation data must be sent out in either EASYCOM I or NOVACOM I format. These two formats send out the desired coordinates as ASCII character strings, accurate to 1/10th of a degree, far more accurate than the Yaesu rotator is capable of achieving.

Setting up the Satellite Tracker Jr.

The red dipswitch selects how this interface operates. A dipswitch bit is ON when the switch is pulled towards the numbers (back of the interface) and OFF when it is pushed away from the numbers (towards the front or display). I use a small tool with a blunt hook in it to reach through the rear access hole and push or pull the desired dipswitch. The #1 switch of the 8 position dipswitch on the interface selects whether Yaesu operation is intended. OFF puts the interface in Non-Yaesu mode; On puts the interface in Yaesu mode. AYaesu Elevation rotatar is designed for 180 degrees of travel. 0 degrees elevation gives 0 volts to the STJ; 90 degrees elevation gives 2.5 volts to the STJ and 180 degrees (flip) gives 5 volts to the STJ. BUt if you want to use the STJ as a digital readout for a big dish (typical Non-Yaesu application for the STJ), you will most likely have a potentiometer directly coupled to the elevationa axis, and have 5 volts across the outer terminals of the potentiometer. This time 0 degrees elevation is set to produce 0 volts at 0 degrees elevation;and 90 degrees only produces about 1.25 volts. The #1 dipswitch will be read by the STJ microcontroller and set the calibrations accordingly.

#2 and #3 dipswitches select the desired variable speed setting. These dipswitches only affect automatic mode. With both #2 and #3 ON, full speed operation always occurs, meaning no slow operation will occur (normal with other trackers, but undesirable). With #2 OFF and #3 ON, Half speed operation occurs when the rotators are within 4 times the programmed dead zone. When #2 ON and #3 OFF, Slow speed operation occurs when the rotators are within 4 times the programmed dead zone. Finally with both #2 and #3 OFF, Crawl speed operation occurs when the rotators are within 4 times the programmed dead zone. I run my Yaesu 5500 Satellite Tracker Jr. with #2 ON & #3 OFF, which provides extremely smooth tracking for me at the "SLOW" rate.

In Yaesu mode (see dipsw #1 above) the #4 dipswitch selects whether a 360 azimuth degree Yaesu G-5400 is used (OFF) or a 450 azimuth degree Yaesu G-5500 (ON) is being used. On the rear panel of the Yaesu 5400 or 5500 rotators are 4 holes for accessing 4 potentiometers. Two of the potentiometers are for calibrating the full scale reading of the azimuth and elevation analog meters. The other 2 potentiometers calibrate the full scale reading of the Satellite Tracker Jr. If you have the wrong Yaesu selected by dipswitch #4, you may have difficulty with azimuth calibration!

In Non-Yaesu mode (see dipsw #1 above), the #4 dipswitch selects whether the STJ operates in manual mode (off) or automatic mode (on). Normally dipswitch #4 will be off unless you have the STJ version with relays that makes the STJ directly run small DC motors on small systems automatically.

#5 and #6 dipswitches select the elevation deadzone in steps of 0 (both OFF), 1, 2, and 4 (both ON) degrees. #7 and #8 dipswitches select the azimuth deadzone in steps of 0 (both OFF), 1, 2, and 4 (both ON) degrees.

My preferred settings for my Yaesu G-5500 with 2 long yagis & a barbecue grill dish are:

Automatic Mode - #1 ON, #2 ON & #3 OFF (SLOW), 4 ON, #5 ON & #6 OFF (1 degree elevation dead zone) and #7 ON & #8 OFF (1 degree azimuth dead zone).

Calibrating the Satellite Tracker Jr to your Yaesu

With the rotator off, plug the Satellite Tracker Jr's 8 pin DIN connector into the 8 pin socket on the rear of the Yaesu control unit. do not activate the com interface, forcing automatic mode into manual operation until com data appears. Turn on power to the Yaesu control unit and the Satellite Tracker Jr. The Yaesu rotator should light up as usual and the motors should not move up, down, right or left unless the front levers are depressed. The microcontroller in the Satellite Tracker Jr should start running. It will clear the LCD and display an initial screen identifying itself and the dipswitch settings. This display will stay for about 2 seconds for you to read and then with dipswitch #1 ON (Yaesu mode) go to Automatic mode, . You can fine adjust the LCD contrast control below the LCD to best suit the illumination in the hamshack. The display will show the Elevation bearing on the left, and the Azimuth bearing on the right, just like the Yaesu analog meters' position. Using the control unit, turn the rotator elevation bearing to 0. Verify that the Satellite Tracker Jr. also reads 0. Now turn the elevation up to 180 degrees on the analog meter (or 90 degrees if your antennas are not set up for 180 degrees in elevation. Your Satellite Tracker Jr. is probably not reading 180 degrees (or 90), so turn the potentiometer on the elevation side marked "OUTPUT VOLTAGE ADJ" so the Satellite Tracker Jr. reads 180 degrees (or 90), exactly the same as the Yaesu analog meter. Using the control unit, turn the rotator azimuth bearing to 0 (North). Verify that the Satellite Tracker Jr. also reads 0. Now turn the azimuth around to 360 degrees (Yaesu G-5400 or G-5600) or 450 degrees (Yaesu G-5500) on the analog meter (or 360 degrees if your antennas are not set up for 450 degrees in azimuth. Your Satellite Tracker Jr. is probably not reading 360 degrees (or 450), so turn the potentiometer on the azimuth side marked "OUTPUT VOLTAGE ADJ" so the Satellite Tracker Jr. reads 360 degrees (or 450), exactly the same as the Yaesu analog meter. If for some reason you can't rotate your antenna to the maximum point, get as high as you can and match the settings as described. —a little electronic theory— The Yaesu controller puts out 0 - 5 VDC on the elevation and azimuth pins of the 8 pin DIN socket. The Satellite Tracker Jr. is reading these and doing a 10 bit A/D conversion on the value, then displaying the resultant value. The UP, DOWN, LEFT, AND RIGHT buttons on the Yaesu control box move the rotator. The azimuth and elevation bearings appear on both the analog meters and the digital display. The digital display provides a much more precise manual positioning of the satellite antenna. If you use your rotator to move a dish in the high Ghz region for local terrestrial contacts, the digital readout will let you precisely set the bearing of the station you intend to contact.

Using the Satellite Tracker Jr. in automatic mode

The big picture: After getting the Satellite Tracker Jr. aligned to your Yaesu and operating correctly in Manual mode, connect the DB9M on the back of the Satellite Tracker Jr. to a Serial COM port on the back of a PC. Sometimes the available PC's Com port connector is a DB25M and sometimes it is a DB9M connector. Newer computers and laptops are DB9Ms. Your local Radio Shack store carries a 6' long DB9F to DB9F cable (26-152) that works fine. This cable + a DB25F to DB9M adapter (26-287) will work if your com port is a DB25M. Sometimes you can find a DB25F to DB9F cable at a computer store, but they are rare. Be sure to get a "straight through" cable, not a "null modem" wired cable.

When dipswitch #1 is ON, the Satellite Tracker Jr. is in Yaesu Automatic mode when com data is received, otherwise it is in Manual mode. The first thing the program does is to look for a valid ASCII data stream in either EASYCOM I or NOVACOM I formats coming to the Satellite Tracker Jr. at 9600 baud on pin 3 of the DB9M connector. If it does not get this signal within 5 seconds, the LCD displays "NO DATA" while it waits for you to get things going. A tracking program, such as Nova and maybe Wisp, either sends the desired coordinates to the interface over the serial COM line in the EASYCOM I format or the NOVACOM I format. The PIC processor compares the received coordinates to the present coordinates, and, when necessary, issues the necessary move commands. The LCD displays the desired elevation and azimuth bearings and the actual bearings as the tracking proceeds. The interface decodes the tracking software and sends out UP, DOWN, LEFT, AND RIGHT commands to the Yaesu control box, which then moves the rotator.The EASYCOM I or NOVACOM I bearings provide a 1/10 of a degree accuracy, great for even big dishes, better than most analog precision potentiometers can deliver.

Setting up the Tracking Program Nova

Select "Rotator Setup". In the Interface type box select "Novacom I" or "Easycom I". Select the desired serial port, either COM1 or COM2. If the rotator is the North centered Yaesu G-5400 or G-5600, select the azimuth 180-0-180 box as shown at the left. If the rotator is the South centered Yaesu G-5500, select the 0 - 360 box as shown on the right. If your coax can handle 180 degree elevation rotation, select 180 degrees of elevation. This will avoid an occasional tracking break when your rotator has to reorient due to rotator end limits. Open the baud rate tab and make sure the baud rate is still set to the default 9600 BPS. Click OK.

Using the Satellite Tracker Jr on Small Dishes

The Satellite Tracker Jr. has space on the PCB for adding four small relays, 4 diodes, and a special power connector for running small dishes up to 5' in diameter. Once connected this way, the Satellite Tracker Jr. should not be connected to a Yaesu rotator. The dish should be activated with two small DC motors, and two precision potentiometers, one on the elevation axis and the other on the azimuth axis, which send back their coordinates to the Satellite Tracker Jr.. The dishes will generally be an 18" dish Network dish, the 3' barbecue grill type, or the 30" x 40" oval PrimeStar dish. By adding a small 435 MHz yagi beside the dish, a complete antenna system can be easily built that works well on AO-40, and is extremely portable. The small dish system is configured so that it appears to the Satellite Tracker Jr. as a Yaesu G-5500 with dipswitch #4 ON. Dipswitch #1 will be off so the STJ will correctly read the elevation potentiometer. The main difference will be that the motors on the small dish are small 6 VDC to 12 VDC motors instead of the AC motors on the Yaesu. A small power supply should be provided which can power the motors, provide an adjustable regulated voltage for each potentiometer, and power the Satellite Tracker Jr. The power supply should move the azimuth and elevation axes at the rate of 1 RPM to ½ RPM. The potentiometer on the elevation axis should provide ~1.25 VDC when the elevation axis is at 90 degrees and 0 VDC when the elevation axis is at 0 degrees. The ~5 VDC from the external power supply will be set to an exact value slightly under 5 VDC when the mount is calibrated. The potentiometer on the azimuth axis should provide ~4 VDC when the azimuth axis is at 360 degrees, through the South to 0 VDC when the azimuth axis is at 0 degrees. The ~54VDC from the external power supply will be set to an exact value when the mount is calibrated.

Use

If your Yaesu rotator snags its coax and is stalled too long, the motor that is stalled can burn up. This happened to me a couple of years ago. The stalled motor burned out, the power transformer in the Yaesu control unit burned out, and then the fuse blew. About $350 worth of damage. Nice of it to try to protect the fuse that way. Make sure your dish is moving reliably before leaving unattended. It is a good normal practice to park the antenna in position safe from high wind. I switch the tracking box on NOVA to off so the Satellite Tracker Jr. reads "NO DATA", and manually turn my antennas East at 0 degrees elevation. Then turn the Yaesu control box off.

Updates

The Satellite Tracker Jr uses a small preprogrammed 16F877 PIC microcontroller. Design improvements and corrections are accomplished by simply obtaining a new part from me and plugging it in in place of the current microcontroller. The cost of this service is $10 pp. I wish I could update my '97 Toyota this cheaply!

Problems & Repairs

Bad things happen. Lightning Strikes. Units fall. LCDs get zapped by static electricity. If you ever need service for your unit, send it back to me with a $30 check and a description of the trouble. I will either fix & update or replace the unit and mail it back to you ASAP.

The Yaesu rotator system uses 12 wires to send voltages to two AC motors and read two potentiometers. If the wires at the two terminal 3s (potentiometer ground lines) have any appreciable resistance between the control unit and the motors, the rotator will be unable to reach 0 degrees. When using the small analog meters on the Yaesu, this was not too apparent. But the precise digital readout on the STJ makes this stand out like a sore thumb. Every ohm in an azimuth terminal 3 lead produces about is about .9 degrees offset. Every ohm in an elevation terminal 3 produces .36 degrees offset. 6 ohms in the elevation terminal 3 lead can result in serious tracking problems for the Satellite Tracker Junior at 0 degrees elevation.

3/1/2006

My PCB house went out of business and destroyed all of my negatives without warning me. I have no Satellite Tracker Minis left at this tune, and I am not planning on making any more Satellite Tracker Minis. The Satellite Tracler Junior continues to be very popular, and I currently have 10 more units under construction and these will be availabe for purchase in a few days.

The Satellite Tracker Junior is now $225 postpaid USA, $235 USA funds drawn on a USA bank, postpaid to other countries.

I ship out the Satellite Tracker Juniors USPO Priority mail upon receipt of a check or money order, usually theday after receiving the funds. I am not set up to accept credit cards or Paypal.

Dr. Robert Suding W0LMD

27107 Ricmond Hill Rd.

Conifer, Colorado 80433

(303) 838- 6346