Specifications

Although the relay contacts are rated at 120 volts AC,
it is not recommended that 120 volts AC be connected to the AFS-1. The screw-
terminal connectors have several exposed points that could produce a
dangerous or even lethal shock if they were contacted. Low voltage AC or DC is
much safer and eliminates the potential for a shock hazard.
The "G" terminal next to the "RELAY" terminals is a connection to the internal circuit
ground but it is not connected to the case.
5.6 Audio Connections
Audio connections are made to the AFS-1 through the screw-terminal connector on the
left hand side of the front panel. There is an "A" channel input and a "B" channel input.
Either one or both channels may be used. If two stereo channels are fed to the inputs,
note the polarity of the audio connections or cancellation of the signals will result in the
AFS-1. If only one audio source is used, connect it to either input and leave the other
input disconnected. The "G" terminal is connected to the internal circuit ground and its
use is optional.
Generally, the most desirable location to "tap" the audio signal for use by the AFS-1 is a
point where the signal level is somewhere between 0 dBm and +10 dBm. This could be the
output of a discrete STL, the output of audio processing equipment, or the transmitter's
audio input terminals. Note should be made of installations using telephone lines for
program audio sources. Since the audio level of incoming telephone lines is generally in
the range of -30 dBm, the output of a processing device would be a good monitoring point
in such installations. The audio input impedance of the AFS-1 is approximately 60 KΩ so
bridging the AFS-1 across a program source usually has no significant effect.
After installing the AFS-1 be sure to test that the "AUDIO" LED does in fact go off if audio
is lost. Otherwise the timing interval will never begin and the AFS-1 will not work as
intended.
5.7 Loss of Power to AFS-1
It should be noted that if power is lost to the AFS-1, the control relay will open. If it is
necessary to disconnect power to the AFS-1 without opening the relay contacts, place the
switch on the front panel in the "DEFEAT" position before disconnecting power.
5.8 Safety Considerations
If the AFS-1 is connected so that loss of audio turns a transmitter off, the return of audio
could turn a transmitter back on. Operating and maintenance personnel should be
mindful of this possibility and be sure the transmitter is rendered inoperable before
maintenance is begun on the transmitter, antenna, or associated equipment.
Version 2.00 Installation page 5.2