Heat And Ventilation; Linear Amplifier Interfacing - Vertex Standard FT-857 Operating Manual

minimize interference to your communications caused by energy from the computer. Computer-generated RFI is usually a
result of inadequate shielding of the computer's cabinet or I/O and peripheral connections. While computer equipment
may "comply" with RF emission standards, this does not ensure that sensitive Amateur Radio receivers like the FT-857
will not experience interference from the device!
Be certain to use only shielded cables for TNC-to-Transceiver connections. You may need to install AC line filters on the
power cord(s) of the suspected equipment, and decoupling ferrite toroidal chokes may be required on interconnecting
patch/data cables. As a last resort, you can try installing additional shielding within the computer's case, using appropriate
conductive mesh or conductive shielding tape. Especially check "RF holes" where plastic is used for cabinet front panels.
For further information, consult amateur radio reference guides and publications relating to RFI suppression techniques.
To ensure long life of the components, be certain to provide adequate ventilation around the cabinet of the FT-857. The
cooling system of the transceiver must be free to draw cool air in from the side of the transceiver and expel warm air from
the rear of the transceiver.
Do not install the transceiver on top of another heat-generating device (such as a linear amplifier), and do not place
equipment, books, or papers on top of the transceiver. Place the transceiver on a hard, flat, stable surface. Avoid heating
vents and window locations that could expose the transceiver to excessive direct sunlight, especially in hot climates.
The FT-857 provides the switching and drive-control lines required for easy interfacing to most all commonly-available
amplifiers sold today.
These include:
ρ The Antenna Jacks ("HF/50MHz" and "144/430MHz");
ρ
A T/R control line (open circuit on RX, closure to ground on TX); and
ρ
A negative-going ALC jack (control voltage range: 0V to –4V DC).
ρ When interfacing to the VL-1000 Solid State 1 KW Linear Amplifier, the optional CT-58 Interface Cable provides for
easy interconnection (requires that the Menu Mode No-020 [CAT/LIN/TUN] setting changes to "LINEAR").
The rear-panel ACC jack is a miniature stereo type, which accepts ALC control voltage input on the tip connection, and
T/R control on the ring connection. The main shaft is used for the ground connection.
Typical amplifier interface circuits are shown below.
Note that some amplifiers, particularly VHF or UHF "brick" amplifiers, offer two methods of T/R switching: application
of +13V or a closure to ground.

Heat and Ventilation

Heat Water & Moisture

Linear Amplifier Interfacing

Dust Ventilation
10
FCC ID: K66FT-857
Operating Manual
Vertex Standard Co., Ltd.