SG-2000 MANUAL
21
The SGC Building, 13737 S.E. 26th St. Bellevue, WA. 98005 USA
©1995, SGC, Inc.
TEL: (206) 746-6310 FAX: (206) 746-6384
cockpit.
Aviation.
Installation on aircraft presents an unusual challenge. In most cases, the
control head is mounted separately from the radio. This allows the radio unit to be
placed very close to the aircraft center of gravity.
7.3
Control Head Wiring
The control head cables which are used with the SG-2000 are designed for use in normal
conditions. This means that the cables are suitable for use in mobile and fixed
installations. Very high vibration environments and mounting in military situations
require special precautions.
In high vibration environments, wire chaffing must be avoided. Although it will take
more installation time, secure all wiring tightly to prevent movement. Once movement
begins, the protective covering of wiring can be quickly worn away. This is especially
true on a tug boat, for example, where vibration caused by the ship's large propeller can
cause 1/8" to 1/2" vibration and rates of 10 cycles per second or more. A shaking
control head wire moving even a fraction of an inch as it passes through a clamp will
ultimately fail.
Military installations require a different approach. The danger here is not vibration but
shrapnel. The most common methods used are either to bury the cable in a trench one
half meter deep, or, if the ground is hard or rocky, to place one or more layers of sand
bags over the cable.
7.4
External Speakers
The SG-2000 has no separate front panel headphone jack because the radio front panel
is weather-resistant and a headphone jack is just another hole that reduces the weather
resistance of the control head.
If you plan to use high impedance headphones, such as the type included in a telephone
handset, you will connect these to the radio via the microphone jack. On the other
hand, use of a low impedance headphone requires the use of the external speaker jack,
which is present on the rear panel of the SG-2000 main unit. The J-505 jack, the external
speaker jack, is also where a low-impedance Weatherfax modem may be connected.
The speaker jack on the rear of the SG-2000 is controlled like the front panel speaker.
In other words, when the SPK (speaker) is disabled on the control head, the remote
speaker which is wired in parallel with control head #1 speaker is also turned off.
Important Note: The rear panel speaker is only available
when the control head of the SG-2000 is attached to the
radio. This is because a separate speaker audio line is run
from the attached control head (where the audio amplifier is