Satellite Tracker Senior by SAI
The Satellite Tracker Senior. is a new dish moving interface, aimed at the medium to large parabolic dish market. This unit is designed to be as low cost as possible, yet offer features never before seen on dish controllers.
The Satellite Tracker Senior takes its user inputs from four pushbutton keys on the front panel. In automatic mode, the Satellite Tracker Senior is sent the desired azimuth and elevation bearings from the satellite tracking program, NOVA, in EASYCOM I or NOVACOM I protocal. Another potential user input is an IBM keyboard that can be attached to the Satellite Tracker Senior for direct entry of calls or names, and bearings..
The Satellite Tracker Senior can provide solid state motor drivers for DC or AC types of motors, and also has four high current transistor drivers for driving external relays on very large dishes.
Position inputs to the Satellite Tracker can be precision potentiometers, incremental encoders, or absolute encoders.
A PIC processor, the 17C756, provides the intelligent interaction between user, inputs, and outputs. A non volatile EEPROM stores the user actions so that when the unit is used in the future the default settings will be those of the last user.
Connecting the Satellite Tracker Senior
An external 12 VDC to 25 VDC power supply is connected to the Satellite Tracker Senior. If AC motors are used, then an AC source of power will also be required.
Installing the Satellite Tracker Senior
DC Power Input Terminals
The Satellite Tracker Senior has a 19 position terminal behind the Azimuth display. The innermost position, screw terminal 1, is a Ground terminal, along with screw terminal 15. Screw terminal 2 is the positive voltage input terminal, getting its voltage from an external power supply.
DC Motor Terminals
Screw terminals 3 and 4, beside the power supply input terminals, are used for the two Elevation DC motor leads. The 3951W Elevation DC motor driver delivers the output voltage with the appropriate polarity to these 2 pins when the Elevation motor needs to be run.
Screw terminals 5 and 6, beside the Elevation output terminals, are used for the two Azimuth DC motor leads. The 3951W Azimuth DC motor driver delivers the output voltage with the appropriate polarity to these 2 pins when the Azimuth motor needs to be run.
Since most installations will just be running two DC motors, just the above 6 terminals will be used.
A third 3951W DC motor driver has its output to Screw terminals 7 and 8. This currently unimplemented output was designed for driving a DC motor used for radiation polarity changing.
The next 5 screw terminals, 9 through 13, are outputs from the solid state AC relay modules. The AC input, from 12 VAC to 30 VAC, is connected between screw terminals 14 and 15 (Ground). AC screw terminal 14 serves as a common input to the five solid state relays.
AC Terminals
Screw terminals 9 and 10 provide Elevation AC power. Typically these will be connected to a small rotator such as a U100 with an AC rated capacitor also connected between screw terminals 9 and 10.
Screw terminals 11 and 12 provide Azimuth AC power. Typically these will be connected to a small rotator such as a CDR or a HAM-M series with an AC rated capacitor also connected between screw terminals 11 and 12.
Screw terminal 13 provides AC power for releasing the Azimuth brake used in the Ham-M series of rotators.
Relay Drivers
Screw Terminals 16 to 19, nearest the TIP120 keyiing Darlington pair transistors, provide high current NPN open collector outputs for driving external relays or other keying circuits. They have also been used for driving the Yaesu family of Satellite Rotators.
Screw Terminals 16 and 17 provide elevation keying (grounded = true). Screw terminals 18 and 19 provide Azimuth keying (grounded = true).
Encoder Inputs
The dishes that the Satellite Tracker Senior will be connected to must provide feedback to the Satellite Tracker Senior, telling it what the current Elevation and Azimuth bearings are. These bearing encoders can be precision potentiometers, incremental encoders, or absolute encoders. Potentiometers and incremental encoders are input to the DB15F connector and absolute encoders use the DB9F connector.
4 of the DB15F pins (pins 3,4,5, and 6) provide a ground connection to the potentiometers and incremental encoders. 3 of the DB15F pins (pins 11, 12, and 13) provide regulated +5 volts to the potentiometers and incremental encoders.
Pin 7 of the DB15F connects to the wiper of the precision potentiometer connected to the Elevation axis, if a potentiometer is used as an Elevation encoder.
Pin 8 of the DB15F connects to the wiper of the precision potentiometer connected to the Azimuth axis, if a potentiometer is used as an Azimuth encoder
Pin 1 of the DB15F connects to the Phase A and pin 2 of the DB15F connects to Phase B of the incremental encoder connected to the Elevation axis, if an incremental encoder is used as an Elevation encoder.
Pin 9 of the DB15F connects to the Phase A and pin 10 of the DB15F connects to Phase B of the incremental encoder connected to the Azimuth axis, if an incremental encoder is used as an Azimuth encoder.
Pin 14 and pin 15 of the DB15F are two more A/D converter inputs from potentiometers, but are currently not implemented in firmware.
The DB9F connector usage is currently unimplemented in firmware, but is reserved for a serial port input of up to a pair of 14 bit absolute encoders.
Communications I/O
The Satellite Tracker Senior is designed to receive its desired Elevation and Azimuth bearings input from a 9600 baud serial com line sending out the bearings in either Easycom I or Novacom I protocol, accurate to 1/10 of a degree.
My intended source was the satellite tracking program NOVA running on an IBM compatible PC, but at the 2002 Dayton Hamvention, a fellow from the APRS booth across from me came over with his MacIntosh laptop and outputted Easycom II bearings to me which were derived from a GPS receiver on a balloon. As a result, my dish and yagi rotators started tracking this amateur radio balloon which was sending back ATV pictures on 900 MHz.
Pin 5 of the DB9M is ground and the center pin 3 is the inner conductor from a cable attached to the output of an IBM PC. The other 7 pins are unused if you want to make your own straight through cable. Sometimes the available PC's Com port connector is a DB25M and sometimes it is a DB9M connector. Newer computers and laptops have DB9M connectors. 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.
Initial Power On
For normal operation, turn on power to the Satellite Tracker Senior without pressing any front panel buttons. The 17C756 microcontroller in the Satellite Tracker Senior should start running. It will start out with 3 short beeps and then will clear the LCD and display an initial screen and list out the 8 routines that are contained in the firmware. The AUTOMATIC routine will be blinking, indicting that this is the current default routine. If the user does not use the UP or DOWN keys to move the blink to one of the other 7 routines, then after 20 blinks the AUTOMATIC routine will start running.
You can fine adjust the LCD contrast controls below the LCDs to best suit the illumination in the hamshack. A small hole under the right lower corner of each LCD lets the user access a contrast adjusting potentiometer.
The left LCD will show the Elevation bearings and settings, and the right LCD will show the Azimuth bearings and settings.
Calibration
The Satellite Tracker Senior has internal routines which can only be accessed by pressing a front panel key during power on. The main internal routine to initially set is the one that establishes the motion limits of the dish attached to the Satellite Tracker Senior. These can be modified later to values more approriate to the user, but the four options will put the user closed to any imaginable dish activity. AO-40 mode sets the motion limits to the maximum points that occur in the Northern Hemisphere. In Azimuth, AO-40 only appears in the East through South to the West. It never appears to the North of due East or due West. In Elevation, AO-40 will be somewhere between at the horizon (0 degrees) to about 50 degrees high. Many TVRO dish conversions will not do full 360 degree Azimuth rotation.
Terrestrial use may require a full 360 degrees mount so stations in any direction may be worked. These stations will not be up in the sky, but could be up a slight hill, so 0 to 10 degrees elevation should be fine.
If using the Satellite Tracker Senior to track the Low Earth Orbiting Satellites (LEOs) a Full 360 degree range of Azimuth motion is needed along with 0 to 90 degrees of Elevation motion.
Another desirable motion range is tracking the LEOs with Flip. In this mode certain LEO orbital patterns are best suited by have a mount that can go 360 degrees in Azimuth and 180 degrees in Elevation.
There is no need to access the routine setting these 4 patterns unless you are radically changing the application of the dish system.
Setting Limits
Turn the Satellite Tracker Senior off. Make sure the LCDs go blank, then wait about another minute.
While depressing the "UP" key, turn on the Satellite Tracker Senior. Instead of giving the usual 3 short beeps, the Satellite Tracker Senior will clear both LCDs and put the message "SET LIMITS" on the left LCD.
When the "UP" key is released, the 2 LCDs will change their messages. The left LCD reminds the user to hit the "UP" key to raise the blinking option and the "DOWN" key to lower the blinking option. The right LCD at the top reminds the user that if he presses the "WEST" key the blinking option will be selected, and if he presses both the "UP" and "DOWN" keys simultaneously he will exit this routine without changing the current setting.
After 20 blinks the routine will automatically go to the next option and blink it.
Assuming you want to set your dish for strictly AO-40 use, make sure that "AO-40" is blinking and press the "WEST" key. The default limit values of 90 degrees East and 270 degrees West will be set for Azimuth and 0 degrees to 60 degrees Elevation will be set. In a later routine these values can be easily modified, but most users will fine them acceptable.
If "TERRESTRIAL" is blinking, then 0 degrees and 360 degrees Azimuth by 0 degrees to 10 degrees Elevation will be set if the "WEST" key is pressed..
If "FULL" is blinking, then 0 degrees and 360 degrees Azimuth by 0 degrees to 90 degrees Elevation will be set if the "WEST" key is pressed..
If "FLIP" is blinking, then 0 degrees and 360 degrees Azimuth by 0 degrees to 180 degrees Elevation will be set if the "WEST" key is pressed..
Set Encoders & Motors
When the "UP" key is released after being depressed during power on, the LCDs are cleared and the "SET ENCODERS & MOTORS" routine is started, bypassing the main menu. Options blinking on the left LCD set the Elevation inputs and outputs. When the blinking option is on the right LCD, an Azimuth input or output option can be selected.
The first item blinking on the left Elevation LCD will be Potentiometers, with Incremental Encoder, Absolute Encoder, and NO Encoder also shown. If your mount uses a potentiometer to tell what the elevation is, select this option by pressing the "WEST" key. If your mount uses an Incremental Encoder, etc., then hit the "UP" key to move the blink upwards (or the "DOWN" key 7 times to wrap around), then press the "WEST" key. You have now defined the elevation input type.
Now that the type of position encoders have been defined, the next thing to do is to define the type of motor used on youur mount. Most mounts for TVRO dishes will use DC gearmotors to move the dish in azimuth and a tracker arm with a DC motor will move the dish in elevation. But you may decide to use the Satellite Tracker Senior to move one of the TV type of rotators or perhaps one of the HAM-M family of rotators that have a position holding brake. Very large dishes can be driven by the Satellite Tracker Senior if the on board TIP 120 power transistors are used to activate external relays controlling larger motors.
The first item blinking on the left Elevation LCD will be DC Motor, with AC Motor, AC Motor and Brake, Relay, and NO Motor also shown. If your mount uses a DC motor to move the elevation axis, select this option by pressing the "WEST" key. If your mount uses an AC Motor, etc., then hit the "UP" key to move the blink upwards (or the "DOWN" key 7 times to wrap around), then press the "WEST" key. You have now defined the elevation motor type.
An operational deadzone for the elevation axis must now be selected. The deadzone setting prevents oscillation or endlesss perfect position seeking when the elevation axis nears the desired position. This dead zone should be as small as possible to avoid reducing system pointing accuracy. If you have excellent potentiomers or incremental encoders and no backlash in your axis, a .5 degree deadzone will give you a moount that will track within .3 degrees either side of center. With a 10' dish having 2.8 degrrees beam width, this would keep the signal peaked right on the button for hours at a time. On the other hand if you dish is being driven by a Ham-M family of rotators. you may have to select a 6 degree azimuth deadzone due to the coarseness of the holding brake in these rotators.
The first item blinking on the left Elevation LCD will be .5 degree, with 1 degree, 2 degrees and 6 degrees also shown. Use the smallest deadzone your mount can handle without seeking, and select this option by pressing the "WEST" key.
The next item selects how the Satellite Tracker Senior handles the motors when it is very close to the desired position. Most rotator systems have two speeds, full ON and full OFF. I would hate to have a car that moved like this. The Satellite Tracker Senior allows each motor slow rate to be set so that it will move at a reduced rate when it nears the desired position. Because it is moving at a reduced rate, there is less chance of overshoot and seeking, which means a lower deadzone can be used for greater accuracy. Most of the TVRO dishes I have used the Satellite Tracker Senior on worked well with the Deadzone on .6 degree and the Speed on Half. Ideally the speed setting also sets the coasting amount so that when tracking the motor coasts to exactly the middle of the deadzone, setting the dish to exactly the desired bearing. Too slow tends to track on one edge, and too fast tracks on the other edge, possiblyovershooting, but either will be within the beamwidth, hopefully.
The first item blinking on the left Elevation LCD will be Crawl, Slow, Half, and Full also show. Use the speed that sets your mount consistently closest to the desired bearing.
Now do the same for the azimuth axis.
The first item blinking on the right azimuth LCD will be Potentiometers, with Incremental Encoder, Absolute Encoder, and NO Encoder also shown. If your mount uses a potentiometer to tell what the azimuth is, select this option by pressing the "WEST" key. If your mount uses an Incremental Encoder, etc., then hit the "UP" key to move the blink upwards (or the "DOWN" key 7 times to wrap around), then press the "WEST" key. You have now also defined the azimuth input type.
The first item blinking on the right azimuth LCD will be DC Motor, with AC Motor, AC Motor and Brake Rely, and NO Motor also shown. If your mount uses a DC motor to move the azimuth axis, select this option by pressing the "WEST" key. If your mount uses an AC Motor, etc., then hit the "UP" key to move the blink upwards (or the "DOWN" key 7 times to wrap around), then press the "WEST" key. You have now also defined the azimuth motor type.
The first item blinking on the right azimuth Elevation LCD will be .5 degree, with 1 degree, 2 degrees and 6 degrees also shown. Use the smallest deadzone your mount can handle without seeking, and select this option by pressing the "WEST" key.
The first item blinking on the right azimuth LCD will be Crawl, Slow, Half, and Full also show. Use the speed that sets your mount consistently closest to the desired bearing.
You set and change this as much as you wish, and when you have define the inputs and outputs the way you want them, hit the "WEST" and "EAST" keys simultaneously for a dauble beep. Your settings will then be loaded into the EEROM in the Satellite Tracker Senior, customizing this unit to your dish environment and then the firmware will take you to the next logical activity, Calibrate Sensors. If at some point you decide that you really don't want to change how the system works, just hit the "UP" and "DOWN" keys together to abort out to the main menu without writing the new settings into the EEROM and the firmware will take you back to the main menu.
Calibrate Sensors - Set Limits
Now that you have told the Satellite Tracker Senior what kind of position encoders and motors are used on you mount, it's time to calibrate the sensors to the actual dish position. The front panel keys are first used to modify or accept the end of motion settings that were preset by the power on sequence with the "UP" key pressed, if you used it. The directions for setting these limits are placed on the two LCDs. I could have designed this section to set one limit at a time, but I speeded it up somewhat by letting the user set both the elevation and azimuth. The first position pair to calibrate is: Set Low dish limit and East dish limit. My 10' Janeil dish will not travel below 3 degrees, so I change the low limit to 3.0 degrees with the "UP" and "DOWN" keys. Since I am using my dish just for AO-40 which never goes N of 90 degrees, I accept these two limits and push the "WEST" and "EAST" keys simultaneously, getting a double beep. If for some reason I decide that I dont want to change anything, I can abort out by pressing "UP" and "DOWN" simultaneously which will take me to the main menu without loading anything new into the EEROM.
The second position pair to calibrate is: Set High dish limit and West dish limit. Since I am using my dish just for AO-40 which never goes above 50 degrees elevation or N of 270 degrees, I accept these two limits and push the "WEST" and "EAST" keys simultaneously, getting a double beep, and loading these four new limit values into EEROM. If I decide to do some Moonbounce work with the dish, then I would raise the High Dish Limit to 70 degrees. If I want to park the dish looking straight up, then setting the limits to 90 degrees elevation would be appropriate, if your dish can move to 90 degrees elevation! Obviously, don't set your limits to values your dish can't achieve or you will eventually get a jam. The Satellite Tracker Senior constanly looks for jams anytime a motor is on, and if it finds a jam it wi turn all motors off and display a message telling which motor is jammed to avoid burning out an expensive motor. If for some reason you decide that you don't want to change anything, you I can abort out by pressing "UP" and "DOWN" simultaneously which will take me to the main menu without loading anything new into the EEROM.
Calibrate Sensors - Calibrate Encoders to Limits
The next step will calibrate the position encoders to the mount, using the end limits just set to get the highest level of accuracy. Since the Satellite Tracker already knows the elevation and azimuth encoder type, motor type, and limits, these final calibration steps tie everything together so that double precision math routines can interpolate encoder values to achieve a mount position accuracy up to 1/10 of a degree in azimuth and elevation.
Like the limit setting, the encoder calibrating is done in pairs to save time. Since the Satellite Tracker Senior knows what kind of motors you are using on your mount, the "EAST" "WEST" "UP" and "DOWN" keys are used to move the dish to the desired position. Once the dish is physically at the limit bearing pair, pressing "EAST" and "WEST" simultaneously causes the Satellite Tracker Senior to accept encoder readings at the two limits. The first time you use the Satellite Tracker Senior on a new mount or new encoders, make sure that when you move UP or WEST the encoder value displayed goes higher in value! If it goes lower in value and a potentiometer is used, reverse the + and - leads to the offending potentiometer(s). If incremental encoders are used swap the phase A and phase B leads at either the encoder or the DB15 M connector. Make sure your potentiometers or encoders are firmly locked to the elevation and azimuth axes. Any slippage will destroy calibration validity.
The first calibration pair, Lower Elevation Limit and Eastern Azimuth Limit, requires the dish to be at the lower elevation limit (normally 0 degrees) and the Eastern limit, probably 90 degrees for AO-40 and 0 degrees for Terrestrial work. 0 degrees elevation is not tough to fine with a simple bubble level, but due East will require some precise alignment with the stars or a magnetic compass with deflection offset for your location taken into consideration.The azimuth protractor on my 10' dish has proven its value many times over. Using the front panel UP and DOWN keys, turn the dish to 0 degrees elevation or whatever your lower elevation limit is. Then use the "EAST" and "WEST" keys to move the dish to the lower azimuth limit. Press "EAST" and "WEST" simultaneously to get a double beep and go to the next encoder pair calibration.
The second calibration pair, Upper Elevation Limit and Western Azimuth Limit, requires the dish to be at the upper elevation limit (whatever you set it to between 10 degrees and 90 degrees) and the Western limit, probably 270 degrees for AO-40 and 360 degrees for Terrestrial work. 90 degrees elevation is not tough to fine with a simple bubble level but some kind of an elevation protractor will be needed for other high elevation limit setting. Due West will require some precise alignment hopefully using that azimuth protractor after problems you had setting due East. Using the front panel UP and DOWN keys, turn the dish to 60 degrees elevation or whatever your upper elevation limit is. Then use the "EAST" and "WEST" keys to move the dish to the upper azimuth limit. Press "EAST" and "WEST" simultaneously to get a double beep and load the calibration values into EEROM, then go to the main menu; everything is ready to use. If you press "UP" and "DOWN" simultaneously, you will wind up at the main menu as well but without loading any calibration constants into EEROM.
The settings for my 10' Janeil dish used on AO-40 are:
Potentiometers on both Azimuth and Elevation axes.
DC Motors on both Azimuth and Elevation axes.
.5 degree Elevation dead zone & Slow speed.
.5 degree Azimuth dead zone & Half speed.
3 degrees lower limit to 60 degrees upper Elevation limit.
90 degrees Eastern limit to 270 degrees Western Azimuth limit.
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Operational Modes
The Satellite Tracker Senior has several routines useful for the moving of these larger dishes. The Manual routine lets the user move the dish East, West, Up or Down by pressing the four front panel keys.
Automatic Operation
In automatic mode, a computer running a satellite tracking program. NOVA or APRS is plugged into the DB9M connector on the Satellite Tracker Senior . The computer sends azimuth and elevation bearings to the Satellite Tracker Senior, and the interface takes over control of the motors on the dish, activating the up, down, right or left functions in response to desired azimuth and elevation coordinates.
.By using the front panel "EAST", "WEST", "UP", and "DOWN" keys the user can enter offsets to the bearings provided by the computer. In a perfect situation, offsets are not needed. But sometimes the mount is not exactly calibrated, the computer does not have the latest data (Keplers) to use in bearing calculations, or unknown causes result in the bearings giving the best signal being different from the "Desired" bearings. The "Offset" bearings, negative or positive, are added to the "Desired" bearings and the "Resultant" bearings are then used to compare against the "Actual" bearings to determine dish movement. These offset values are loaded into the EEPROM to be used in future automatic operations until changed.
The Automatic mode requires data over an RS-232 line operating at 9600 baud, repeating less than every 2 seconds. 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 beamwidth of even the largest amateur dish.
Setting up Nova to Novacom I or Easycom I (either ok)
Select "Rotator Setup". In the Interface type box select "Novacom I". Select the desired serial port, either COM1 or COM2. Select the desired bearing limits if you haven't already. Open the baud rate tab and make sure the baud rate is set to 9600 BPS. Click OK.
Manual Operation
In manual mode, this interface reads the analog poteniometer voltages or incremental values proportional to the azimuth and elevation position of the dish and determines where the dish is currently pointed.. These elevation and azimuth bearings are displayed on the dual LCDs as the "ACTUAL" bearing and loads these bearings as the default desired bearings. The user then presses one of the 4 front panel keys to change.this default desired bearing. By holding down the key, the bearing change gets faster and faster to speed up major bearing changes. When the key is released and depressed again the speed up starts over for fine adjustment. The 17C756 monitors the difference between the desired and the actual bearings and turns on the appropriate motor(s) to make the desired change. The interface provides large digital displays of the elevation and azimuth bearings, accurate to up to 1/10 of a degree, depending on the accuracy of the potentiometers or digital encoders.
Park Dish
In Park Dish mode, the firmware reads the desired park bearings from the EEROM, displaying them on the dual LCDs as the "DESIRED" bearing then gets the azimuth and elevation position of the dish and determines where the dish is currently pointed.. These elevation and azimuth bearings are displayed on the dual LCDs as the "ACTUAL" bearing.. The user can press the 4 front panel keys to change.thedesired Park bearing if he wishes. By holding down the key, the bearing change gets faster and faster to speed up major bearing changes. When the key is released and depressed again the speed up starts over for fine adjustment. When the "WEST" and "EAST" keys are pressed simultaneously, the difference between the desired and the actual bearings are calculated the appropriate motor(s) are turned on to make the desired change. If the Park bearings are changed, the new bearings are saved in EEROM and the Saellite Tracker Senior will use these new bearings the next time Park Dish is executed.
Exercise Dish
In Exercise Dish mode, the firmware retrieves several bearing sets and when "WEST" and "EAST" keys are pressed simultaneously, the Satellite Tracker Senior goes to these bearings one after the other. THis mode is very useful for testing dish movement and for demonstrations of dish movement to spectators.
Move to Call/Name
The Move to Call/Name mode provides a unique capabilty. A standard IBM keyboard is plugged into the front of the Satellite Tracker Senior. This keyboard lets the user build up a unique list of calls or names, along the the bearings associated with these calls or names.The calls/names are store in the Satellite Tracker Senior's EEROM for later recall For instnace, in terrestrial work, The keyboard could be used to enter several dozen calls and their bearings so that at a later time, by simply typing a call the dish automatically turns to the bearings of the desired station. Another application might be recalling the bearings of several Geosyncronous Satellites by name.
The Move to Call/Name routines are still under development.
Encoder Values & Exit
This special routine lets the user see the values which the Satellite Tracker Senior is receiving from either Potentiometers or Incrmental Encoders and view the resulted interpolated position as the dish is moved by pressing the "UP", "DOWN", "EAST" or "WEST" keys. It is a handy way to find out what is happening if the dish's movements arre not what you might suspect.
Updates
The Satellite Tracker Senior uses a small preprogrammed 17C756 PIC microcontroller. Design improvements and corrections are accomplished by plugging a new part in place of the current microcontroller. The 17C756 is a PLCC shaped part that requires a special tool to remove the old 17C756. The new part then simply snaps into place. The cost of this service is $20 pp. if you are able to handle the replacement and $30 if you want me to do it. I wish I could update my '97 Toyota this cheaply!
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 $50 check and a description of the trouble. I will either fix & update or replace the unit and mail it back to you ASAP.
Dr. Robert Suding - W0LMD roberts@qadas.com