The following paragraphs describe the most commonly encountered application
problems. If you are having difficulties with Vega equipment, please review this
information and take any necessary corrective action prior to returning the equipment
for repair.
Battery
The most common problems with wireless-microphone systems are those related to the
batteries. Vega recommends that only new, fresh Duracell MN1604 or “Eveready”
Energizer No. 522 alkaline batteries be used. No other batteries tested by Vega have
been found to provide equal life and equivalent reliability. Unfortunately, batteries
purchased in drug stores and supermarkets may not be fresh and frequently do not yield
rated life (6 to 8 hours is the usual range). Regular “9-volt” carbon cells have much
shorter lifetimes (two to three hours for a fresh unit, perhaps less than one hour for a
unit which has been on a rack for a year or so). Cheap “bargain” cells may not work at
all, because they often are really 7 volts instead of 9 volts, and may not be able to
supply the required current.
Rechargeable cells (“ni-cads”) are sometimes used in wireless equipment. The units
commonly sold are almost always 7.2 volts instead of 9 volts and provide only a few
minutes of operation. The only acceptable rechargeable battery known to Vega is the
Varta, which is a true 9-volt design. Even here, the usable life will be much less than
for a Duracell (usually two to three hours).
Battery contacts must be clean and unbroken. The battery tension spring in the
transmitter (opposite to the battery contacts) must also be intact. Attempted forced
reverse insertion of a battery is practically impossible, but the attempt will often
damage the battery contacts. Some “9-volt” batteries sold are larger (or smaller) than
standard and may either fail to work or may damage the contacts when inserted.
Damage to the contacts usually requires a return to the factory or authorized service
center.
Exhausted batteries will cause numerous problems, including distortion, audible squeals
and howls, poor range, and off-frequency operation. It is strongly recommended that the
battery be checked prior to each use, and that it be replaced if there is any question
about its condition. It is also good practice to try replacing the battery with a fresh unit
in the event of any sort of problem with the system, because a low battery may affect
system operation in subtle ways.
Receiver Noise
Vega wireless-microphone receivers are designed to be extremely sensitive. Although
high-performance squelch circuits are provided, it is not unusual for the receiver
squelch to open and let through audio noise when the transmitter is off. This is usually
due to the presence of weak carriers on the receiver frequency due to second-harmonic
output of FM radio stations, spurious outputs from two-way radio transmitters, adjacent-
channel leakage from TV transmitters, and, in some cases, RF noise from industrial
equipment. When the wireless transmitter is “on”, this noise is suppressed and rarely
causes any difficulties. However, if the audio channel is left “open” with the transmitter
“off”, loud blasts of noise may occur. For this reason, it is advisable to “fade” the
receiver audio when the transmitter is not in use.
Acoustic Feedback
Bodypack transmitters usually use lavalier electret microphones. Almost all such
microphones are omnidirectional (equal sensitivity in all directions) and usually pick up
more ambient noise than the handheld microphones to which performers are
accustomed. The characteristic “sound” of lavalier microphones is also quite different
from the usual dynamic handheld microphone, partially because they are electrets and
usually sound “brighter” than dynamics. In many sound systems, on-stage monitors are
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R-27 Portable
