Specifications

56
¥ Facilities and algorithms are used, which enable accurate tuning at the low
end of the frequency band, and the use of even shorter antennas than
previously possible.
¥ The BITE (Built-In-Test-Equipment) Indicator Tune LED includes a safety
feature which alerts the operator to a mismatched condition, via
blinking indicators, when proper tuning conditions have not been met.
In this situation, the software will "time out" within 20 seconds unless a
new frequency is sensed, which will cause an immediate time out, and
the coupler will attempt to match the new frequency.
The sophisticated MicroTuneª software of the SG-235 enables precise tuning
of the coupler components and tuning of a wide variety of antennas.
The microprocessor of the coupler is turned on every time that the coupler
has forward power. However, re-tuning takes place only if the VSWR is
greater than 2:1, or if the frequency has changed. Upon initiation of the tun-
ing, one of the five tuning paths is selected for the initial tuning, depending
on the condition of the tuning indicators.
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When DC power is applied, the computer initializes the processor registers in
accordance with the hardware. All tuning elements are then removed and the
'tune' indicators are turned off. At this time the computer reverts to a "sleep"
mode awaiting RF power.
When RF power is verified, the computer will perform a test to verify forward
power is present. If no forward power is detected, the computer will revert
back to the "sleep" mode.
Once forward power is detected, the current transmit tuning element data is
sent to the relays and the VSWR is checked. If the VSWR is greater than 2:1,
the program branches to the 're-tune' selection. If the VSWR is less than 2:1,
the current frequency is compared to the most recent frequency employed. If
a difference in frequency is detected, the program again branches to the re-
tune program. If it is determined that the VSWR is less than 2:1 and the fre-
quency has not changed, the computer returns to the "sleep" mode.
Once it is determined that re-tuning is necessary, a test is made to see if 'J3' is
set to tune from memory. If the result is re-tuning from memory, the frequency
is measured and tuning data is recalled from the memory based on the
frequency measured.
SGC Inc. SGC Building, 13737 S.E. 26th St. Bellevue, WA 98005 USA
P.O. Box 3526, 98009 Fax: [phone] Tel: [phone] or 1-800-259 7331
E-mail: [e-mail] Web site: http://www.sgcworld.com
© 1998 SGC Inc
SG-235 Manual