User manual WILFA H93

[. . . ] It will match an amazing range of antennas and impedances, far greater than some other tuners you may have considered. Also, it consumes very little power while tuning and zero power otherwise, which makes it ideal for battery-powered operations. LDG pioneered the automatic, wide-range switched-L tuner in 1995. Leonard, Maryland, LDG continues to define the state-of-the-art in this field with innovative automatic tuners for every amateur need. Jumpstart, or "Real hams don't read manuals!" Ok, but at least read this one section before you transmit: 1. [. . . ] The radio will automatically switch to CW mode, transmit a carrier and start a memory tune. When the tuning cycle ends, the radio will automatically unkey and revert to its previous mode. If no match is found the tuner will automatically start a full tune cycle. If a good match is found (SWR of 1. 7 or below), the setting will be stored to memory. Full Tune If you want to force a full tune cycle, press and hold the tune button on the H93 until the red light comes on, then goes off, then release. The radio will transmit a carrier and the tuner will start a full tune (does not look at the memories). When the tuning cycle ends, the radio will automatically unkey and revert to its previous mode. If a good match is found, the setting will be stored to memory. Bypass mode To place your H93 in bypass mode, press the Tune button on the front of the H93 tuner and quickly release before the red LED comes on (less than a half-second). The tuner will switch to bypass; RF from your FT-897 transceiver will go directly to the antenna with no matching. There are no LED indicators for the bypass mode. An SWR of 1 (sometimes written 1:1) indicates a perfect match. As more energy is reflected, the SWR rises to 2, 3 or higher. As a general rule, modern solid-state transmitters must operate with an SWR of 3 or less. Tube exciters are more tolerant of high SWR. If your 50-ohm antenna is resonant at your operating frequency, it will show an SWR of 1. However, this is usually not the case; operators often need to transmit at frequencies other than resonance, resulting in a reactive antenna and a higher SWR. 1 For a very complete treatment of this subject, see any edition of the ARRL Radio Amateur's Handbook 10 SWR = 1+ R / F 1- R / F where F = Forward power (watts), R = Reflected power (watts) SWR is measured using a device called an "SWR bridge", inserted in the transmission line between the transmitter and antenna. This circuit measures forward and reverse power from which SWR may be calculated (some meters calculate SWR for you). More advanced units can measure forward and reverse power simultaneously, and show these values and SWR at the same time. An antenna tuner is a device used to cancel out the effects of antenna reactance. Tuners add capacitance to cancel out inductive reactance in the antenna, and vice versa. Simple tuners use variable capacitors and inductors. [. . . ] With the best inductor selected, the tuner then steps through the individual capacitors to find the best coarse match. If no match is found, the routine repeats the coarse tuning with the high/low impedance relay energized. The routine then fine-tunes the capacitors and inductors. The program checks LC combination to see if a 1. 5 or lower SWR can be obtained, and stops when it finds a good match. [. . . ]