16
a negative correction factor (making elements shorter) until SWR is low will allow
antenna to operate normally. When water, snow or ice is gone, put antenna
correction back to original setting. This feature allows the user to use antenna in
any weather conditions with no performance degradation, as opposed to fixed
element length Yagi’s which may be unusable for as long as elements have water,
snow or ice on them. It can also be useful in some cases of interaction or low
antenna height situations.
Calibrate Antenna
Selecting
Calibrate
causes an antenna calibration to be performed. Whenever antenna is
not acting as it should, activating
Calibrate Antenna
function is recommended before
exploring other potential problems. This is the first thing to try if antenna is exhibiting
higher than usual SWR or decreased performance. The main reason for “uncalibrated
antenna situation” is loss of power while elements are extended. This is because there is a
small holding voltage present at all times to keep elements from moving when it is not
being tuned. Note that it is not necessary to calibrate for each band.
Calibrating antenna ensures element lengths are accurately reported by controller. The
controller does not know where antenna element is unless it is started from a “known”
place. Even if elements are fully retracted, controller still retracts full length of tape plus
some extra length. The stepper motors will continue to over-step for a short period of time
after elements have reached the stop. In doing this, controller is making sure there is no
doubt each element is fully retracted and back to a known starting point. Retraction is
performed at low motor power levels and doesn’t cause any damage to EHU. The
calibration procedure usually remedies most cases of elements being off in their length.
The elements are then re-deployed to appropriate length for operating frequency when
calibrate was initiated. Calibration can take two minutes or more depending on selected
frequency and antenna model and cannot be aborted. A
Calibrate
operation can be
executed
at any time in any mode. It doesn’t matter what frequency the user is on when
calibrating. When calibration is completed, antenna is calibrated at all frequencies.
Upon delivery, the EHU initially has each element fully retracted and controller is set to
home. If controller is powered up and it says elements home and antenna control cable is
connected with elements physically retracted, system is calibrated and ready to go.
Always calibrate when in doubt - it is easy, and doesn’t hurt a thing.
Retract Elements
To retract antenna elements, press
RETRACT
. The
Power/Tuning
LED will flash amber
and green. When LED stops flashing, antenna elements are now fully retracted inside
EHU. To put antenna back on air, simply press antenna segment desired. Controller will
adjust to that segment.
