INSTALLATION

ANTENNA CONSIDERATIONS

The antenna systems connected to your FT-857transceiver are, of course, critically impor- tant in ensuring successful communications. The FT-857is designed for use with any an- tenna system providing a 50 W resistive impedance at the desired operating frequency. While minor excursions from the 50 W specification are of no consequence, the power amplifier’s protection circuitry will begin to reduce the power output of there is more than a 50% diver- gence from the specified impedance (less than 33 W or greater than 75 W, corresponding to a Standing Wave Ratio (SWR) of 1.5:1).

Two antenna jacks are provided on the rear panel of the FT-857. The “HF/50 MHz ANT” jack is used for HF and 50 MHz, while the “144/430 MHz ANT” jack is used for 144 MHz and 430 MHz.

Guidelines for successful base and mobile station installations are shown below.

Mobile Antenna Installations

Mobile antennas for the HF bands, with the possible exception of those designed for 28 MHz, display very high “Q” due to the fact that they must be physically shortened, then resonated using a loading coil. Additional system bandwidth may be realized using the Yaesu FC-30Automatic Antenna Tuner, which will present a 50 W impedance to your transceiver on the 1.8 ~ 50 MHz bands so long as the SWR on the coaxial line connected to the FC-30is below 3:1.

On the VHF and UHF bands, coaxial line losses increase so rapidly in the presence of SWR that we recommend that all impedance matching to 50 W be performed at the antenna feedpoint.

Yaesu’s Active-Tuned Antenna System (ATAS-100/-120) is a unique HF/VHF/UHF mo- bile antenna system, which provides automatic tuning when used with the FT-857. See page 68 for full details on the ATAS-100/-120.

For VHF/UHF weak-signal (CW/SSB) operation, remember that the antenna polarization standard for these modes is horizontal, not vertical, so you must use a loop or otherwise horizontally-polarized antenna so as to avoid cross-polarization loss of signal strength (which can be 20 dB or more!). On HF, signals propagated via the ionosphere develop mixed polar- izations, so antenna selection may be made strictly on mechanical considerations; vertical antennas are almost always utilized on HF for this reason.

In mobile (and portable) installations, when vertical antennas are used, remember that the grounding of the base area of the antenna is critically important to proper operation. Since most HF vertical antennas emulate a quarter-wavelength “monopole” antenna, the “missing half” of the dipole antenna consists of a counterpoise of radial ground system. In a vehicle, if mounting the antenna to a door or hatch, it is recommended that you bond the door to the

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FT-857 Operating Manual

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Vertex Standard FT-857 manual Mobile Antenna Installations, Antenna Considerations
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FT-857 specifications

The Vertex Standard FT-857 is a compact and versatile all-mode transceiver that has become popular among amateur radio operators since its introduction. With its ability to operate in VHF, UHF, and HF bands, the FT-857 caters to a diverse range of communication preferences and provides exceptional performance for both mobile and base station applications.

One of the key features of the FT-857 is its coverage of a broad frequency range, spanning from 160 meters to 2 meters and covering the 70 cm band. This wide frequency coverage allows amateur operators to communicate with fellow enthusiasts across various bands, ensuring versatility in operational environments. The FT-857 offers an output power of up to 100 watts on HF and 50 watts on VHF/UHF, providing sufficient power for effective communication, whether in local or distant contacts.

Another distinctive characteristic of the FT-857 is its all-mode capability. It supports various modes of operation, including SSB, CW, AM, and FM, making it suitable for different operating styles and preferences. The inclusion of advanced digital signal processing (DSP) technology enhances audio clarity and offers noise reduction features, which are crucial in crowded bands. This DSP capability also aids in improving signal quality and overall communication experience.

Portability is a significant advantage of the FT-857. Its compact size and lightweight design make it an excellent choice for field operations and portable setups. Additionally, the transceiver is well-equipped with features such as built-in memory channels, allowing users to save and quickly access frequently used frequencies. The FT-857 also includes a built-in automatic antenna tuner, which makes it easier for operators to set up and optimize their antenna configurations without requiring additional external devices.

The FT-857 is designed with user-friendly controls and a clear LCD display, enabling operators to quickly adjust settings and monitor communication details without confusion. The visibility of the display is especially vital for use in different lighting conditions, ensuring that users can operate efficiently whether in bright sunlight or low light conditions.

In summary, the Vertex Standard FT-857 is a highly capable, compact transceiver that offers an effective solution for amateur radio communication. With its all-band, all-mode capabilities, robust DSP technology, and user-friendly design, the FT-857 remains a popular choice for both enthusiasts and professionals alike, facilitating engaging communication experiences across multiple bands and modes.
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