Specifications

SMARTUNER MANUAL 40
SGC Inc. SGC Building, 13737 S.E. 26th St. Bellevue, WA. 98005 USA
© Nov2000 SGC, Inc. P.O. Box 3526, 98009 Fax: [phone] Tel: [phone]
E-Mail: [e-mail] Web Site: www.sgcworld.com
RF Input ST-1
RF GND Input ST-1
13.6 (24) VDC ST-7
DC GND ST-8
RF Output ST-9
RF GND Output ST-3, ST-4
TND ST-6
Reset/Hold ST-5
The TND line cannot be connected to the SG-2000 and SmartLock units simultaneously.
7.2 Tuning Process
An array of detector devices in the SMARTUNER monitor the antenna system
impedance, reactance signal, and the VSWR load when RF power is applied to the unit.
The coupler also monitors forward power, since the control computer requires an
indication of both forward and reflected power in order to allow tuning to proceed. The
computer uses the forward power detector as a check to ensure that the measurements
made are applied RF and are not spurious levels from the data conversion system. The
SMARTUNER will proceed to tune only when enough forward power is present to
confirm this check.
After RF is applied to the coupler array, it then passes through the detector system. The
detector system consists of six capacitors in shunt on the input arm of network, eight inductors
in the series arm, and five more capacitors in shunt on output arm, all arranged in binary
increments. Relays are provided in conjunction with each lumped constant and allow removal
or entry as desired. A network having 64 values on input shunt C, 32 values of output shunt C,
and up to 256 values of series L is possible with the manipulation of these 26 relays.
7.3 Impedance Detector
RF transformers T1 and T2 drive the impedance bridge that is balanced at 50 ohms. T2 samples
the line current and thus D5 outputs a negative DC level proportional to line current. A
tertiary winding on transformer T1 provides a line voltage sample to D10 that provides a
positive voltage proportional to line voltage. R49 and R50 act as a summing network for the
current and voltage signals, with ratios chosen, such that at 50 ohms, the summed signals
result in a balanced or zero voltage condition.
If the line impedance goes to high, the signal from the voltage sensor will be relatively higher
than the current sensor, which will result in a net positive output voltage from the summing