Copyright ©1997, RF Specialties Group.
AM synchronous noise should be down at least 50dB. How you tune your transmitter will make a difference here. Radio Design Labs makes an AM noise monitor with an alarm closure that can be connected to your remote control system to alert you to a problem.
Pilot injection should be adjusted to within eight to 10 percent. The SCA injection should be set to 10 percent per subcarrier, maximum. Those who lease your SCA will no doubt want more signal, so be prepared to tell them the injection limits. To determine if these injected signals are causing problems, simply kill the injections and operate in mono long enough to check.
Still haven't determined the cause of that swishy, fluttery sound? A malfunctioning stereo generator/processor unit could be the culprit. If possible, try a substitute or check with the manufacturer. In the case of an Orban Optimod 8100A, try replacing socketed IC-704 on card 7.
If all this fails to uncover the noise, multipath could very well be the
problem. In which case, you may still be able to improve reception for fixed
location receivers by using a Yagi directional receiving antenna. Check it out.
Bill
Turney of RF Specialties, Florida, brings to the group a rich broadcast engineering
background dating back to 1969. He was in charge of several radio station construction
projects as an engineering consultant. In 1984, after a stint with McMartin
Industries, he joined RF Specialties. He is part owner of several radio stations,
and holds an FCC General Class and Amateur Extra-Class licenses (WS4Y).