5771-10

5771-10

The Netcom 5771-10 is a tunable bandpass filter covering 30 MHz to 90 MHz, the low VHF band. The centre frequency is set in 125 kHz steps and the 3 dB bandwidth is 10% of the tuned frequency. The filter settles on a new frequency in 10 microseconds.

The 125 kHz step is the finest in the series, and it has to be. At 30 MHz a 10% passband is only 3 MHz wide, so coarse steps would leave gaps. The fine resolution also matches the 25 kHz channel spacing used by combat net radios in this band.

It is part of the TunePro 2W series and handles 2 watts (+33 dBm P1dB) in a 0.575 x 0.575 x 0.250 inch surface mount package. IIP3 is +45 dBm and insertion loss is 4.5 dB typical. Noise figure is less than 0.5 dB above the insertion loss. Rejection is 11 dB at 10% away from the tuned frequency, 17 dB at 15% away and 21 dB at 20% away. Control is by SPI serial interface. The part runs from 3.3 VDC at 30 mA and works from -40 to +85 °C.

Putting a 30 MHz tunable filter in a half inch square surface mount package is the point of this part. At these frequencies the resonators are normally large enough that a tunable preselector is a module, not a component.