SteppIR YAGI URBAN BEAM, Assembly Manual, Page: 43 / 47

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Page 43
SECTION 6.0 TROUBLESHOOTING THE URBANBEAM YAGI
TROUBLESHOOTING TIPS
(Instructions continued on next page)
SteppIR antennas are all powered by stepper motors, hence the name. Stepper motors function by rotating
the shaft a specific number of “ steps ” per revolution. The SDA 100 or OptimizIR directs the stepper motors
to extend the elements a particular number of steps to the required length. If for some reason the antenna
gets out of calibration, the method for recalibrating is pretty simple. When you press the calibrate button,
the controller retracts each element until it assumes it is “ home ”, and then keeps retracting the stepper
motors for a period of time to ensure that there is no question that the elements have indeed been homed.
At that point, the controller sends the elements back out to the frequency they were at when the calibration
function started. That is why in calibration mode you will hear the antennas make a loud growling sound
towards the end of the retracting—the elements are homed but the stepper motors keep right on going for
a while longer before sending the elements back out.
It is important to note that if a problem arises with the elements, such as an obstruction that is impeding
the path of the copper strip, the SDA 100 or OptimizIR controller will not recognize this, so just because
the controller is showing the proper length for any given band, there may still be an issue. Even though the
controller may indicate that the copper strip is moving, in a troubleshooting situation it very well may not
be. The controller does not have much say in the indicating of a problem—its job is to simply get the
elements to the right length. This is why we have come up with the following information for you to review
when having issues:
The antenna is out of calibration —this is something that happens from time to time and is not a
problem at all. Whenever you suspect a problem the very first thing that should be done is a calibrate. It is
always a good idea to calibrate the antenna if you are having trouble. It is best to set the UrbanBeam to
20m before doing the calibrate function. You only need to calibrate once. To be certain that the antenna
was indeed out of calibration, check the SWR before you calibrate and check it again after you calibrate to
see if there are any improvements. If the SWR is unchanged, the antenna was in calibration and is not the
issue.
The lengths of the antenna are incorrect — Using the “ Cause/Effect ” theory, generally the first place to
look for trouble is the last place you have been. Using this line of thinking, if there is a problem with your
antenna, we need to be sure you are using the factory default lengths for your controller. Regardless of
whether you think you have done anything that could change the lengths, as a second step in
troubleshooting (the first being the simple calibration of the antenna), be sure to reset the factory default
lengths.
There is a short or break in the antenna control cable — This is the number one ‘ hard error ’ that
occurs. Breaks or shorts can happen because of gnawing rodents, aggressive weed whacking, freewheeling
rotators, mechanical fatigue, cable pinching between the antenna and any object, weather or UV
deterioration of antenna insulation, and dozens of other reasons. For the UrbanBeam, pairs 1 - 2, 3 - 4, 5 - 6, 7
- 8 are all independent circuits, and should never come in contact with one another or ground. The
resistance between the pairs should be approximately 15 ohms, not including controller cable length (with
100 feet of cable, the resistance will measure approximately 20 ohms). An intermittent short or an
intermittent open while the motors are moving can also cause a driver chip failure. There is no skimping on
carefully checking the resistance between each pair, and making sure no pairs are crossed or grounded.
The SDA 100 electronic controller has a defective or intermittent driver chip — It only takes a
momentary short to damage a driver chip . The problem with driver chips is that a blown driver chip
or a damaged driver chip that has not failed outright can act a lot like a damaged EHU. What we don ’ t
want you to do is jump to the conclusion that it is an EHU issue, only to spend time and money taking your
antenna down and find out that it was a driver chip problem, or some other issue with the controller in the
first place. Taking the time to troubleshoot and repair a controller is MUCH easier than taking down an
antenna to repair an EHU.