User manual

Mailing: PO Box 3526, Bellevue, WA. 98009
Shipping: 13737 SE 26
th
St. Bellevue, WA. 98005
Toll Free: 800-259-7331 * Phone: [phone] * Fax: [phone]
www.sgcworld.com * Email: [e-mail]
47
5.1 Tuning Process and Options
The MAC-200 MicroTune™ Software is unique in that it allows
precise tuning of the digitally controlled π and L network for a
wide variety of antennas. The versatile MicroTune™ software
offers these special functions:
1. The coupler is activates whenever forward power is present.
2. In addition to sampling VSWR to determine if the coupler should retune,
it also does a frequency comparison. This causes the coupler to tune
whenever the transmit frequency changes independent of the VSWR
reading.
3. Many tuning paths test different antenna situations. The initial tuning of
a new frequency (or switched antenna) may require up to two seconds.
Any further tuning happens in a matter of milliseconds if jumper JP3
(Tune From Memory) is in its default position.
4. Facilities and algorithms are used which enable accurate tuning at the
low end of the frequency band—even on shorter antennas than
previously possible.
5. The BITE (Built-In-Test-Equipment) Tune LED includes a safety
feature that alerts the operator to a mismatched condition. When the
proper conditions for tuning are not present, the BITE indicators will
blink. When this happens, the software will “time out” within 20
seconds unless a new frequency is sensed. A new frequency will cause
the coupler to attempt a new match.
Mailing: PO Box 3526, Bellevue, WA. 98009
Shipping: 13737 SE 26
th
St. Bellevue, WA. 98005
Toll Free: 800-259-7331 * Phone: [phone] * Fax: [phone]
www.sgcworld.com * Email: [e-mail]
48
5.1.1 Tuning Process
An array of detector devices in the MAC-200 monitor the antenna
system impedance, reactance, and the VSWR when RF power is
applied. 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 forward
power detector is a check to ensure that the measurements made
are applied RF and are not spurious signals from the data
conversion system. The MAC-200 will tune only when enough
forward power is present to confirm this check. After RF is
applied to the detector system, it passes through the coupler-tuning
array. The coupler-tuning array consists of six capacitors in shunt
on the input arm of the network, seven inductors in the series arm,
and four more capacitors in shunt on the output arm, all arranged
in binary increments. Relays work with each lumped constant and
allow removal or entry as desired. A network having 64 values on
input shunt C, 16 values of output shunt C, and up to 128 values of
series L is possible with the manipulation of these 17 relays.