NCS-3230 Rev C Instruction Manual
Copyright © 2003, 2004 New Communications Solutions, LLC
12
4.5 Hum, Noise and Distortion
Your
Multi-Rx
TM
was designed with care and uses high quality
components and construction. You should not experience any operating
difficulties when you follow the setup and use instructions in this manual.
If you do experience problems, here is some information that may help
you resolve any difficulties.
Hum
Magnetically induced hum can be caused to any modern piece of audio
equipment by too close proximity to unshielded power transformers or
other equipment that radiates strong AC magnetic fields. You can tell if
you have this type of hum by rotating the Multi-Rx
TM
left/right, up/down
and moving its position. If the hum increases and decreases, then you are
experiencing magnetic coupling from an unshielded power transformer or
other equipment. The Multi-Rx
TM
should be several inches away from
equipment that radiates AC magnetic fields.
Another source of hum can be a ground loop. This is a situation when
pieces of audio equipment that are connected together do not have their
grounds well connected. This results in a voltage difference between the
equipment grounds and can be a safety hazard as well as introducing
electrical problems. The solution to this problem is to tie all your
equipment grounds (usually case or chassis) together with a low
impedance RF connection. You should refer to any of the Amateur Radio
publications for extensive discussion of ground loops and how to eliminate
them.
Noise
Excessive noise can be caused by many factors. The Multi-Rx
TM
uses
state-of-the-art low noise amplifier ICs. Nevertheless, even these
components can add a bit of noise or “hiss” to an audio signal if not
adjusted properly. If you seem to have excessive “hiss” type noise, review
the setup and level adjustments you’ve made to the radios connected to
the Multi-Rx.
Excessive noise can also be caused by ground loops. See the previous
“hum” discussion for information on eliminating ground loops.
