Yaesu FT-847 Operating Manual

Also see for FT-847: Technical supplement Technical supplement Technical supplement Modification

Contents

62 FT-847 OPERATING MANUALACTIVE-TUNING ANTENNA SYSTEM (ATAS-100) OPERATIONThe optional ATAS-100 Active-Tuning Antenna System provides operation on the 7, 14, 21, 28, 50, 144, and 430MHz bands.Full instructions for its use are found in the documentation accompanying the ATAS-100.To activate automatic tuning of the ATAS-100, Menu #31 must be changed from its default “TUNER ” setting to“ ANT.” See page 88 for details.OPERATIONAUTOMATIC TUNINGÅ Press the [TUNER] switch momentarily to “turnon” the ATAS-100. The “ TUNER ” icon will ap-pear on the LCD.Ç Now press and hold in the [TUNER] switch for ½second to initiate the tuning procedure. The FT-847 will automatically transmit a carrier, and youwill observe the ATAS-100 extending itself beyondits fully-nested position. During tuning, the S-Meterbecomes a relative SWR indicator, and successfulmatching will be indicated by a sudden “dip” inthe reading on the meter.É When tuning is successfully completed, the FT-847will return to the receive mode.Ñ When changing bands, once a match has been ob-tained via step Ç above, just press and hold in the[TUNER] switch for ½ second to initiate re-tuningof the ATAS-100 for operation on the new band.Although there is no “memory” of antenna posi-tion, the ATAS-100 will raise or lower itself in the“correct” direction if it has successfully achievedan impedance match on one band.Ö For operation on 144 and 430 MHz, the loadingcoil assembly must be fully “nested” at its mini-mum length. If it is not in this position, touch the[TUNER] switch momentarily; the ATAS-100 willretract itself fully, and will turn itself off at thenested position. Operation on the 144 MHz or 430MHz bands may then commence.MANUAL TUNINGIn some instances, the SWR may be slightly improvedby manual adjustment of the antenna position. Thismay be needed for operation on bands like 17 meters,where the “Q” of the ATAS-100 is high, causing anarrow resonance range.To tune the ATAS-100 manually, press the MOXswitch (or press and hold in the microphone PTTswitch). With the transceiver in the “TRANSMIT” mode,press and hold in the [MHZ p] key (to raise the an-tenna) or the [MHZ q] key (to lower the antenna).While you hold in one of these keys, the FT-847 willgenerate a carrier, and you may watch the top scale ofthe FT-847’s meter, looking for the meter indicationto reach its minimum value. When this is reached, re-lease the [MHz] key, then press MOX (or release thePTT key to return to the “RECEIVE” mode.