NCS-C150 Manual Rev A Page 10
9.0 Troubleshooting
The C150 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 the issues.
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 C150 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 C150
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. The best choice
for connecting material is a wide braid or copper strap.
Noise
Excessive noise can be caused by many factors. The C150 uses state-of-the-art low noise amplifier ICs. However,
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 C150 In some cases,
increasing the radio’s own mic gain and decreasing the levels from the C150 may improve the noise level.
Excessive noise can also be caused by ground loops. See the previous “hum” discussion for information on
eliminating ground loops.
Distortion
Distorted audio can be caused by one of two situations. The first and most common is improper adjustment of audio
levels. Be sure you’ve adjusted the Radio and C150 level controls as recommended in this manual and that your
radio’s mic gain control is properly adjusted. Setting the Volume Controls at too high a level can also cause
distortion.
RF at the operating position can also cause distorted audio. To determine whether this is the problem, connect your
transmitter to a dummy load. If the distortion disappears, then you have RF entering the interface cables. To
eliminate RF problems, first make sure you have set up the jumpers and radio cables correctly. Then check that you
have a good ground between all pieces of equipment and that your RF ground is low impedance.
In-band Repeating
In-band repeating requires special attention to prevent one radio from interfering with or desensitizing the other.
Many techniques are available including increasing vertical and horizontal separation of antennas, shielding one
antenna from the other and using different polarizations for each antenna. The specific solution will be determined by
the installation environment and the overall operation conditions. Experimentation will be required.
10.0 Contacting NCS
NCS wants you to experience trouble free operation of our equipment. If you have any questions, comments or need
technical help, please use the following resources:
1. Go to the web site, www.ncsradio.com. Here you will find the latest instruction manuals, any factory developed
modifications and Frequently Asked Questions. Schematics for all NCS products may be found at
www.ncsradio.com/schematics .
2. Email us at support@ncsradio.com. Be sure to include all pertinent information, e.g. make and model of radios,
how they’re connected to the C150, detailed description of any problems, antenna and grounding
configurations, etc.
3. Telephone us toll-free at 888-883-5788.
Note: Be near your equipment and have the manuals for your radios available. We will do our best to help you
using our technical expertise.
