Zaxcom MicPlexer 3 RF Filter & Amplifier

MicPlexer 3 is a RF filter and amplifier offering enhanced frequency coverage, a 50 MHz tuning window, continuous 2 MHz step tuning, variable output level control, and RF overload indicators.

RF bandpass filtering

MicPlexer 3 features a completely overhauled bandpass filter that’s continuously tuneable, providing excellent RF rejection while preventing RF overload from walkie-talkies and mobile devices that can cause intermodulation in the distribution amplifier, ruining the performance of a connected receiver.

The bandpass window has been designed to be as narrow as possible yet wide enough to support a variety of productions, including film, television, and sports.

MicPlexer 3 provides 2 x 1 into 4 output RF paths for the distribution of a diversity antenna system.

Understanding Bandpass

This graphic above shows the passband of MicPlexer 3. The user-adjustable passband filter is centred at 550 MHz and provides approximately 50 MHz of bandwidth with extremely low loss. Signals outside that window are sharply attenuated.

As you can see in the graph, when the bandpass is centred at 550 MHz, signals at 460 MHz (where UHF walkie-talkies operate) are attenuated by as much as -36 dB.

By adjusting the bandpass filter continuously across the spectrum, the user can decide not just what their wireless system is receiving, but also what it attenuates. It is this attenuation characteristic that makes MicPlexer 3 a welcome tool in a sound mixer’s kit, helping to eliminate interference that might affect uninterrupted operation of your wireless system.

Simple specifications, like a frequency range, may not be as helpful in understanding how much attenuation can be expected in terms of interfering signals. The real worth of a filter is in its overall curve and attenuation figures.

Knowing the shape of the bandpass for any product will help in making an educated decision when designing a wireless system with robust performance and frequency agility.

Operating Range

MicPlexer 3 is continuously tuneable from 470–665 MHz and 745–965 MHz.

A small portion of the spectrum, 660 MHz to 720 MHz, is not included, as only specially licensed mobile devices are allowed to use this portion.

Tuning Window

MicPlexer 3 features a continuously adjustable 50 MHz tuning window. For example, if the MicPlexer 3 is tuned to 550 MHz, the unit will pass RF information between 525 MHz and 575 MHz, and sharply attenuate RF information outside that window.

The steep attenuation of this filter allows for unrivalled flexibility in frequency selection and prevents interference and overloading from unwanted signals.

Tuning Accuracy

MicPlexer 3 is continuously unable across its spectrum in 2 MHz frequency steps, giving the user a high degree of flexibility when choosing available spectrum for use.

It is the MicPlexer 3’s tuning accuracy and customisation that makes it preferable to distribution products with SAW filters. Its sharp bandpass rejection and adjustability also make it superior to products with fixed high-pass filters.

RF Amplification

MicPlexer 3 has an excellent amplifier, with a noise figure of 0.35 dB and an OIP3 of +34 dB. The device can handle any high-RF environment, adding protection through its high-Q RF filtering.

SMA antennas are used on both inputs, making it simple to bypass the MicPlexer 3.

RF Distribution

MicPlexer 3 supports two amplification channels with four outputs. Outputs are user-adjustable:

• Operating between 470–665 MHz is selectable from -10 dB to +6 dB relative to the input signal.
• Operating between 745–965 MHz is selectable from -10 dB to +3 dB relative to the input signal.

Overload Indicator

MicPlexer 3 has an overload LED indicator for each antenna input. If the unit determines that the received RF signal is too strong, the LED will indicate an overload condition.