Continental Electronics 816R - Automatic Recycle Resetting; Theory of Operation; General Theory; Functional Description

relative to 800 VDC when the primary taps
match the line voltage. The primary taps can
be used to adjust TPO providing that the taps
used must not be more than two taps lower than
line voltage. Example-line voltage is 230
VAC. You may use any Screen Transformer
primary tap higher than 210 VAC but not the
200 VAC tap. If your line voltage is 245
VAC, you may use any primary up higher than
230 VAC but not the 220 VAC tap.
6. Reapply primary power and press the
FILAMENT ON and PLATE ON switches on
control panel Al.
7. Repeat Steps c through f until the maximum
transmitter output is approximately 5 % above
the authorized sution maximum output.
8. Adjust the POWER ADJUST control until the
POWER OUTPUT meter displays the
authorized station maximum power output.
F. 2nd POWER LEVEL (low pwr) ADJUSTMENT
NOTE
Perform this step only if using a second
power level.
1. Switch transmitter to AUTO POWER
CONTROL mode.
2. Apply 28 V de to A10TB2-1, Remote Control,
to activate relay A2A6K1.
3. Adjust Power Monitor (Control Card) A2A6R7
for the desired power level.
G. AUTOMATIC RECYCLE RESETTING
Automatic transmitter shutdown occurs when PA
Screen, PA Plate, or VSWR is overloaded. An
overload indicator, A1CR16 through A1CR18,
illuminates on Control Panel Al. The automatic
recycling circuits restart the transmitter. The
indicator lamp remains on until the transmitter
operator presses the FAULT RESET switch on the
main control panel. The fault indicator lamp cannot
be RESET from Remote Control location. Perform
maintenance procedures if the automatic recycling
circuits fail to restart the transminer.
The fault recycling circuits may be tested by using
switch the RECYCLE TEST SWITCH A2A5S1 or
disabled by switching the AUTO RECYCLE switch
A2A5S2 to OFF.
HI. THEORY OF OPERATION
A. GENERAL
The FM Transmitter, 816R transmitters, operate in
the 88 to 108 MHz range at maximum rated RF
outputs of 21.5 (816R-2C), 25 (816R-3C), 27.5
(816R-4C), 30 (816R-6C) and 35 kW (816R-5C). A
CEC 802B solid state, wideband, FM exciter
provides excitation. The transmitter is equipped with
circuits that maintain constant power output and
protect the transmitter from overload conditions. A
control panel provides complete transmitter metering
and tuning controls. Refer to the overall schematic
diagrams for detailed circuit information.
B. FUNCTIONAL DESCRIPTION
Refer to Figure 2, an input signal (monaural, stereo
composite, or SCA) is supplied to the exciter. The
exciter ’ s RF output drives a two stage power
amplifier. The first stage, the intermediate power
amplifier (IPA), amplifies the input to a level of 500
Watts. The last stage, the RF power amplifier,
amplifies the RF signal to the transmitter ’ s rated
power output. The power amplifier is followed by a
low pass filter and a directional coupler which is
connected to the station ’ s antenna system. A de
sample of the forward power from the directional
coupler (DC1) is monitored by the auto power
control circuit. If a change in output power is
detected, a signal is sent to the power control board
that increases or decreases the plate and screen
power supply input voltage to compensate. A sample
of the reflected power is also monitored by the
power control circuits. If an excessive amount of
reflected power is detected, the control circuits
remove the transmitter plate voltage. The 28 V de
power supply provides power for the control
circuits.
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