4-2
4-11.
OUTPUT COUPLING.
Energy is coupled into the transmission line by an adjustable un
tuned loop which functions in the electromagnetic field within the cavity. One end of the
output loop is connected to ground, while the other connects to the center conductor of the
output transmission line through flexible straps.
4-12.
PLATE TUNING.
Plate tuning is accomplished by adjusting a
threaded rod which mechani
cally expands or contracts a beryllium copper bellows on the end of the grounded transmis
sion line center conductor inserted into the main line. Coarse frequency adjustment is ac
complished by pre-setting the length of the center conductor into the cavity.
4-13.
NEUTRALIZATION.
Neutralization is accomplished in the FM-5T/FM-5TS by distributed
inductance added in series between the screen connection and the screen bypass capaci
tors. The inductance develops a counteractive voltage swing between the screen and
ground which cancels out the voltage fed through the internal capacitances of the tube and
the stray capacitances of the tube socket. This form of self-neutralization results in very
stable operation and requires no adjustment when the power tube is replaced.
4-14.
SECOND HARMONIC SUPPRESSOR.
A patented second harmonic suppressor is in
cluded in the PA cavity. This consists of a capacitive disc and a series inductance to ground
coupled to the main transmission line at the fundamental frequency RF voltage null point.
Here the second harmonic exhibits a high voltage and the suppressor presents a low im
pedance to ground which reduces the amplitude of the second harmonic. This unique
method of harmonic suppression has minimal effect on the fundamental frequency and
does not add losses to the PA cavity at the fundamental frequency.
4-15.
OUTPUT CIRCUIT.
A separate low-pass filter is contained within the FM-5T/FM-5TS
cabinet to attenuate all residual second and higher order harmonics. This filter functions
over the entire FM broadcast band. Three RF directional couplers are mounted after the
filter in the output transmission line connection. Two of these supply filtered forward and
reflected power RF samples to the controller and the third port supplies a forward power
sample at 40 dB below carrier at 50 Ohms for external test equipment.
4-16.
TRANSMITTER CONTROLLER.
4-17.
Transmitter control operations and parameter monitoring are performed by a built-in
microprocessor based controller. The controller incorporates extensive use of RFI filtering,
optical isolation, and state-of-the-art microprocessor technology to assure maximum reli
ability.
4-18.
The controller is designed with 12 switch/indicators, 9 status indicators, 3 modem ports,
and a printer port. Adjustable timers are provided to determine filament warm-up time,
blower run-down time, overload-recycle time, and warm-up defeat time. In addition, the
controller is equipped with adjustable plate, screen, grid, and VSWR overload limits. The
timers and the overload limits are adjusted by controls on the main circuit board. The
range of all controls is limited, however so that the safe operating limits of the transmitter
cannot be exceeded by incorrect adjustment.
4-19.
All transmitter control and monitoring operations are directed by a state-of-the-art
Z-SOFT microcontroller. The microcontroller is housed on a single plug-in daughter cir
cuit board. The circuit board plugs directly into a header on the controller main circuit
board.
4-20.
The controller operates from a modular switching power supply assembly. Three LEDs on
the main circuit board monitor the status of the +5V, +15V, and -15V power supplies. A
Lithum battery backup system has been incorporated into the circuit design. The battery
is designed to maintain the controller memory during power failures and has a useful life
of approximately 2 years.
Содержание FM-5T
Страница 1: ...FM 5T FM 5TS 5 KILOWATT FM BROADCAST TRANSMITTERS July 1999 IM No 597 0033 014 ...
Страница 7: ...5 COPYRIGHT 1997 BROADCAST ELECTRONICS INC 597 0098 408 FIGURE 2 FM 250C REAR PANEL CONNECTIONS ...
Страница 14: ...1 3 FIGURE 1 1 FM 5T FM 5TS TRANSMITTER 597 0033 1 COPYRIGHT 1990 BROADCAST ELECTRONICS INC ...
Страница 20: ...597 0033 400 FIGURE 2 1 FM 5T FM 5TS TRANSMITTER INSTALLATION 2 3 2 4 COPYRIGHT 1997 BROADCAST ELECTRONICS INC ...
Страница 21: ...2 5 FIGURE 2 2 ACCEPTABLE AC POWER INPUT CONFIGURATIONS 597 0099 11 COPYRIGHT 1997 BROADCAST ELECTRONICS INC ...
Страница 23: ...2 7 FIGURE 2 3 REMOTE CONTROL INTERFACING SHEET 1 OF 2 597 0220 418 COPYRIGHT 1997 BROADCAST ELECTRONICS INC ...
Страница 24: ...2 8 COPYRIGHT 1997 BROADCAST ELECTRONICS INC 597 0220 418A FIGURE 2 3 REMOTE CONTROL INTERFACING SHEET 2 OF 2 ...
Страница 29: ...2 13 COPYRIGHT 1997 BROADCAST ELECTRONICS INC 597 0033 415 FIGURE 2 4 TRANSFORMER TAPS ...
Страница 32: ...2 16 597 0033 406 FIGURE 2 6 FM 5T PRIMARY AC WIRING COPYRIGHT 1997 BROADCAST ELECTRONICS INC ...
Страница 41: ...597 0033 408 FIGURE 3 1 CONTROLS AND INDICATORS 3 3 3 4 COPYRIGHT 1997 BROADCAST ELECTRONICS INC ...
Страница 46: ...3 9 TABLE 3 2 INDICATOR CHECKLIST 597 0098 412 ...
Страница 49: ...597 0033 409 FIGURE 4 1 FM 5T FM 5TS BLOCK DIAGRAM 4 3 4 4 COPYRIGHT 1997 BROADCAST ELECTRONICS INC ...
Страница 60: ...597 0033 410 FIGURE 4 4 RF CIRCUIT SIMPLIFIED SCHEMATIC 4 17 4 18 COPYRIGHT 1997 BROADCAST ELECTRONICS INC ...
Страница 61: ...4 19 FIGURE 4 5 PA CAVITY 597 0032 32 COPYRIGHT 1997 BROADCAST ELECTRONICS INC ...
Страница 83: ...5 22 WARNING DISCONNECT POWER PRIOR TO SERVICING BLANK PAGE ...
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Страница 120: ...FIGURE 7 17 ASSEMBLY DIAGRAM PA INPUT CIRCUIT Sheet 1 of 4 597 0033 105A COPYRIGHT 1997 BROADCAST ELECTRONICS INC ...
Страница 121: ...COPYRIGHT 1997 BROADCAST ELECTRONICS INC 597 0033 105B FIGURE 7 17 ASSEMBLY DIAGRAM PA INPUT CIRCUIT Sheet 2 of 4 ...
Страница 122: ...FIGURE 7 17 ASSEMBLY DIAGRAM PA INPUT CIRCUIT Sheet 3 of 4 597 0033 105C COPYRIGHT 1997 BROADCAST ELECTRONICS INC ...
Страница 123: ...597 0033 105D COPYRIGHT 1997 BROADCAST ELECTRONICS INC FIGURE 7 17 ASSEMBLY DIAGRAM PA INPUT CIRCUIT Sheet 4 of 4 ...
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Страница 127: ...FIGURE 7 20 ASSEMBLY DIAGRAM DIRECTIONAL COUPLER 597 0032 506 COPYRIGHT 1990 BROADCAST ELECTRONICS INC ...
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Страница 130: ...COPYRIGHT 1997 BROADCAST ELECTRONICS INC 597 0033 413 FIGURE 7 23 ASSEMBLY DIAGRAM PA MATCHING CIRCUIT BOARD ...
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Страница 151: ...COPYRIGHT 1997 BROADCAST ELECTRONICS INC 597 0220 423 FIGURE 1 1 TRANSMITTER CONTROLLER BLOCK DIAGRAM 1 3 1 4 ...
Страница 158: ...COPYRIGHT 1997 BROADCAST ELECTRONICS INC 597 0220 417 FIGURE 2 1 CONTROLLER MAIN CIRCUIT BOARD CONTROLS 2 3 2 4 ...
Страница 167: ...COPYRIGHT 1997 BROADCAST ELECTRONICS INC 597 0220 416 FIGURE 2 2 CONTROLLER COMPONENT LOCATIONS 2 13 2 14 ...
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Страница 188: ...COPYRIGHT 1997 BROADCAST ELECTRONICS INC 597 0220 429 FIGURE 4 8 ASSEMBLY DIAGRAM TRANSMITTER CONTROLLER Sheet 1 of 4 ...
Страница 189: ...COPYRIGHT 1997 BROADCAST ELECTRONICS INC 597 0220 430 FIGURE 4 8 ASSEMBLY DIAGRAM TRANSMITTER CONTROLLER Sheet 2 of 4 ...
Страница 190: ...COPYRIGHT 1997 BROADCAST ELECTRONICS INC 597 0220 431 FIGURE 4 8 ASSEMBLY DIAGRAM TRANSMITTER CONTROLLER Sheet 3 of 4 ...
Страница 191: ...COPYRIGHT 1997 BROADCAST ELECTRONICS INC 597 0220 432 FIGURE 4 8 ASSEMBLY DIAGRAM TRANSMITTER CONTROLLER Sheet 4 of 4 ...