BE FM-1B, 1 kW FM Transmitter

 The BE FM-1B uses the same Eimac 3CX1500A7/8877 triode used in the FM-1.5B to produce more than 1 kW of power and is designed for applications requiring 250 to 1100 watts of RF power. The PA is driven directly by the ex­citer. Operates from 208/240 volt single phase 50/60 Hz. The FM-1B and larger transmitters use the same controller and com­panion automatic power control and the new revolu­tionary FM exciter, the 50 watt FX-50, for outstanding audio performance.

Main Cabinet Dimensions: 23.31 "W x 31.25"D x 69.81"H, Main Cabinet 760 lbs.

RF Output: 7/8" EIA                 

AC Input: 196 to 252 VAC, 50/60 Hz, single phase

AC Power consumption: 2.2 kW (0.99 pf)

FX-50 Exciter provides audio performance that rivals CD's.

·         Single tube high-efficiency design.

·         Patented folded half-wave output cavity eliminates plate blocker and sliding contacts.

·         Automatic power control maintains constant RF output power.

·         Proportional VSWR foldback and exclusive "soft start" reduces power supply stress and allows turn on into high VSWR loads.

·         True emergency "by-pass" operation.

·         Low noise, high efficiency air cooling system for long tube life.

·         Complete remote control interface built-in.

·         Extensive metering of PA parameters for ease of tuning and adjustment.

·         Optional Microprocessor Video Diagnostic System (MVDS) and MVDS Remote Control available.

Folded Half-Wave Output Cavity

The new "B" Series FM transmitters use only a single tube to obtain their rated output power. The patented, folded half-wave cavity design com­pletely eliminates troublesome and unreliable DC plate blocking capacitors and all sliding RF contacts. Changing the power tube is easy because B/E's broadband screen neutralizing technique eliminates the need to make neutralization readjust­ment even when the final tube is changed. All PA adjustments are made through smooth operating front panel controls, equipped with counters.

Built-in Precision Envelope Detector

All single tube "B" Series FM transmitters of 1KW and higher power also include a built-in precision envelope detector to make measure­ment of synchronous AM noise easy and convenient. The only additional equipment required is a readily available oscilloscope or audio voltmeter and an audio oscillator. Adjustment of the transmitter for minimum synchronous AM noise can even be done while on-the-air with program audio.

Automatic Power Control

An automatic power control system (ARC) used in all one tube transmitters maintains constant RF output power within 2% of the operator set­ting, if fluctuations occur in incoming AC line voltage, RF drive level, or antenna impedance. The sophisti­cated proportional feedback system corrects power variations without overshoot.

Proportional VSWR Foldback

The first to offer proportional VSWR foldback in FM transmitters, this in­novative feature is included in the "B" Series. In cases of gradual changes in load conditions, such as ice build up on the antenna, the proportional VSWR foldback systems protects the PA by automatically reducing output power to a safe operating level.

A "soft start" circuit is used to gradually increase power to allow the transmitter to come up to a safe operating level under high VSWR conditions.

Advanced Transmitter Controller

The standard transmitter controller in the "B" Series FM transmitter features automatic overload recycling and AC Restart, "step start" and provides direct interfacing to all modern remote control systems. The transmitter con­troller is designed to accommodate BE's exclusive optional MVDS (Microprocessor Video Diagnostic System).

Broadband Solid State IPA

The intermediate power RF amplifier, used in all "B" Series transmitters is a solid state, broadband, 250 watt amplifier. The IPA stage requires no tuning or adjustment and is mounted on slides for easy access. The IPA is equipped with proportional VSWR foldback protection and is open and short circuit protected. In addition, cir­cuits in the IPA Control Regulator pro­tect the RF amplifier from excessive heat, current, and voltage by automatically reducing power to a safe operating level.

In high power "B" Series transmit­ters two solid state IPA's, operating in parallel, are used to provide RF drive power to the final amplifier. Each IPA drawer contains its own power supply and air cooling system, making it capable of operating as a standalone 250 watt transmitter. In addition, if one IPA fails, the other continues to operate. The exciter can be fed direct­ly to the operating IPA or the final amplifier. This "flexible patching" capability first offered by Broadcast Electronics in the FM-30 when in­troduced in 1981, allows bypassing of inoperative stages in order to stay on the air at the highest possible operating power level.