Yaesu FT-847 Operating Manual

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Contents

63FT-847 OPERATING MANUALNotes:m Once automatic matching has been successfullyaccomplished, you must change frequency by atleast 10 kHz before attempting automatic match-ing again. Within a window of ±10 kHz from amatch point, the transceiver's microprocessor willignore any command to attempt automatic match-ing.m Antenna tuning is accomplished using a “CW” car-rier, although the mode indication will not changeto “CW” (if you are operating on another mode)during antenna tuning.m If you see a “H I S W R ” indication on the LCD, itmay mean that there is a problem in your coaxialcable (bad connection, etc.) which is preventingACTIVE-TUNING ANTENNA SYSTEM (ATAS-100) OPERATIONOPERATIONGROUNDINGIt is critically important that you establish a goodmechanical and RF ground connection for yourATAS-100 (as with all vertical antennas). Mobilemounts which are bolted through the vehicle’s roof,or otherwise mechanically affixed, will usually besatisfactory. However, magnetic mounts do not pro-vide the RF grounding necessary for good perfor-mance, and are not recommended for use with thisantenna.TUNING PROCEDUREThe feedpoint impedance of the ATAS-100 (resis-tance and reactance) will necessarily vary over awide range when you change bands. Occasionally,the transceiver’s microprocessor will not initiallybe able to determine the proper direction for theATAS-100 to travel (inward or outward) for bestSWR.To resolve this situation, the transceiver will thencommand the ATAS-100 to retract fully to its mini-mum height, and thence restart the tuning process.In this instance, the “ WAIT ” icon will appear onthe display after you press the [TUNER] button. Ifthis happens, do not press the [TUNER] buttonrepeatedly. The transceiver will remain in the re-ceive mode as it retracts (this may take up to oneminute). Thereafter, the transmitter will be engaged,and the ATAS-100 will be automatically adjustedfor best SWR. The “WAIT ” icon will then disap-pear from the LCD, and you will be ready for op-eration.successful tuning. Replace the cable, or try addinga few feet/meters of cable (to eliminate the possi-bility of adverse “transformer action” in the 50Ωcable during the tuning process).m If you are able to achieve an SWR of less than 2:1via manual tuning, the FT-847 will “accept” themanual setting, and you may then re-tune automati-cally when changing bands.m If, however, you stop manual tuning at a non-opti-mum setting (SWR >2:1), the FT-847 will not per-mit further automatic tuning. To refresh the settingof the ATAS-100, press the [MHZ q] key until theATAS-100 will fully retract. You may then restartautomatic tuning per the procedures described ear-lier.The command which retracts the ATAS-100 to itsminimum height utilizes a fixed timer. If the ATAS-100 reaches its minimum height before the timerhas expired, you may observe the antenna’s motorcontinuing to rotate; this is normal, as the ATAS-100’s retraction mechanism includes a clutch as-sembly to prevent damage to the antenna or motor.EXTERNAL WATTMETERSIf you wish to use an external wattmeter in con-junction with the transceiver and your ATAS-100,please check the wattmeter with an Ohmmeter priorto installation. Be sure there is a direct connectionbetween the “IN” and “OUT” jacks of the wattme-ter (zero resistance), and also ensure that there is acompletely open circuit between the center pin andshield of the wattmeter’s output jack. Some watt-meters use a coil or other device which shorts thecenter pin to ground at DC, and this type of inter-nal wattmeter circuitry will not allow the tuningfunction of the ATAS-100 to operate.OPERATION ON 30/17/12 METERSAlthough the ATAS-100 is not specified for op-eration on the above bands, and optimum opera-tion is therefore not guaranteed, the ATAS-100generally can be tuned successfully on these bands(some manual adjustment may be required). Op-eration of the ATAS-100 on these bands will notdamage the antenna’s components; please feel freeto experiment on these bands, if you like.ATAS-100 Operating TipsThe information below will help you derive the best performance possible from your new ATAS-100 Ac-tive-Tuning Antenna System.