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. 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. Connect the CAT/Linear jack on your FT-897 (D) transceiver to the CAT In jack on your H93 tuner using the provided cable. [. . . ] Attach your antenna lead-in coax to the Antenna jack on the back of your H93 tuner. Your H93 tuner is now ready to use! 8 Operating Instructions Operation couldn't be simpler: Normal operation Simply press the tune button on your H93 tuner until the red LED lights, then immediately release. 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. 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. 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. The operator adjusts them by hand while observing reflected power on the SWR meter until a minimum SWR is reached. If your antenna is far from resonance, the inefficiencies inherent in such operation are inescapable; it's simple physics. Much of your transmitted power may be dissipated as heat in the tuner, never reaching the antenna at all. A tuner simply "fools" your transmitter into behaving as though the antenna were resonant, avoiding any damage that might otherwise be caused by high-reflected power. Another relay switches the entire capacitor bank to the input or output side of the inductor. This switching allows the H93 to automatically handle loads that are greater than 50 ohms (high setting) and less than 50 (low setting). [. . . ] If running at maximum speed, the microprocessor can try all inductor-capacitor combinations in just 8. 8 seconds. Unfortunately, the mechanical relays can't react as quickly as the microprocessor, and the tuning speed must be slowed down to compensate for relay settling time. The tuning routine, written in a computer language, uses an algorithm to minimize the number of tuner adjustments. The routine first de-energizes the high/low impedance relay if necessary, and then individually steps through the inductors to find a coarse match. [. . . ]