Yaesu FT-857 Operation Manual

Also see for FT-857 series: Manual Technical supplement Brochure & specs Operating manual Technical supplement

Contents

Yaesu FT-857 Operation Manual Manual pdf 71 page image

69FT-857 Operating ManualA CTIVE-TUNING A NTENNA SYSTEM (ATAS-100/-120) OPERATIONTRANSMITTER OPERATION6. When you wish to conclude ATAS-100/-120 operation, press the [A](TUNE) key; the“u” icon disappear surrounding the “ATAS” indication.If the ATAS-100/120 retracts to its minimum length, it will not automatically shutoff instantly; it may continue to have its motor engaged for as long as 30 secondsthereafter, until a timer expires. A clutch mechanism prevents damage to the antennawhile this is happening, and this condition is completely normal.Manual TuningIn some instances, the SWR may be slightly improved by manual adjustment of the antennaposition. This may be needed for operation on bands like 40 meters, where the “Q” of theATAS-100/-120 is high, causing a narrow resonance range.To tune the ATAS-100/-120 manually, recall Multi Function Row “k” [TUNE, DOWN, UP],then press and hold in the microphone PTT switch. With the transceiver in the “transmit”mode, press and hold in the [C](UP) key (to raise the antenna) or the [B](DOWN) key (tolower the antenna). While you hold in one of these keys, the FT-857 will generate a carrier,and you may watch the top scale of the FT-857’s meter, looking for the meter indication toreach its minimum value. When this is reached, release the [C](UP) or [B](DOWN) key,then release the PTT key to return to the “receive” mode.R.F. Says: 1) Once automatic matching has been successfully accomplished, you mustchange frequency by at least 10 kHz before attempting automatic matching again. Withina window of ±10 kHz from a match point, the transceiver’s microprocessor willignore any command to attempt automatic matching.2) Antenna tuning is accomplished using a “CW” carrier, although the mode indicationwill not change to “CW” (if you are operating on another mode) during antenna tuning.3) If you see a “HSWR” on the LCD, it may mean that there is a problem in your coaxialcable (bad connection, etc.) which is preventing successful tuning. Replace the cable, ortry adding a few feet/meters of cable (to eliminate the possibility of adverse “transformeraction” in the 50 W cable during the tuning process).4) If you are able to achieve an SWR of less than 2:1 via manual tuning, the FT-857 will“accept” the manual setting, and you may then re-tune automatically when changingbands. If, however, you stop manual tuning at a non-optimum setting (SWR >2:1), theFT-857 will not permit further automatic tuning. To refresh the setting of the ATAS-100/-120, press the [B](DOWN) key until the ATAS-100/-120 fully retracts. You may thenrestart automatic tuning per the procedures described earlier.5) The FT-857 may also be used with the model ATAS-100 antenna, although the tuningspeed of the ATAS-100 will be about 20% slower than with the ATAS-120.