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Operating Manual and User Guide
BROADCAST FM EXCITERS
FM25E
FM50E
FM250E
FM SERIES
PTEK
Limited WarrantyPTEK (SELLER) warrants that products are free from defects in material and workmanship and meet
performance specifications provided, however, that:
(A) SELLER’ liability under this Warranty is limited to repairing or replacing, at its option, any
product delivered here under not conforming to this Warranty;
(B) This Warranty is limited to a period of two years;
(C) Minor deviations from specifications which do not affect performance are excluded from this
Warranty; and
(D) SELLER shall be liable under this Warranty only if:
(1) It is promptly notified in writing by the Buyer upon discovery of the failure of any product to
conform to this Warranty,
(2) The product is returned to SELLER, transportation charges prepaid by the Buyer,
(3) The product is received by SELLER not later than ten days after the last day of the two-year
period of this Warranty, and
(4) SELLER’ examination of the Product discloses to SELLER’S reasonable satisfaction that
such defects or failures as may exist have not been caused by misuse, neglect, improper
installation, repair, alteration, accident or shipping.
The Buyer will prepay freight to and from SELLER on products serviced here under at SELLER’ plant; but
SELLER may, at its option, elect to perform any repairs here under at the Buyer’s place of business.
The foregoing constitutes SELLER’S entire Warranty expressed, implied and/or statutory, except as to
title, and states the full extent of SELLER’S liability to the Buyer or to any other party for any breach of
such Warranty and for damages, whether direct, special, incidental or consequential; and, other than as
expressly provided in this document. No Warranties, expressed or implied, including any Warranty or
merchant ability or of fitness for a particular purpose, are made. No employee, representative or agent of
SELLER has any authority, expressed or implied, to alter or to supplement the terms of this Warranty.
Warranty Service
The Limited Warranty covers parts and labor to the original purchaser for two year. Damage
caused by misuse or shipping is excluded from the warranty. Before returning units or material,
contact the factory for a Returned Material Authorization (RMA) number. Ship all material
prepaid. Defective material should be addressed to:
PTEK
PTEK111 N. Vista Rd. Ste 3E
Spokane Valley, WA 99212(509) 290-6652
Safety
BEFORE APPLYING POWER
GROUND THE EXCITOR.
Fuses
.
DO NOT OPERATE IN AN EXPLOSIVE ATMOSPHERE
DO NOT REMOVE THE EXCITOR COVER
Output connector
Verify that the line voltage is 115V
To minimize shock hazard, the excitor chassis must be connected to an electrical ground. the excitor must beconnected to the ac power mains through a three-conductor power cable, with the third wire firmly connected to anelectrical ground (safety ground) at the power outlet. Any interruption of the protective (grounding) conductor ordisconnection of the protective earth terminal will cause a potential shock hazard that could result in personal injury.If the excitor is to be energized by any other source be certain the that chassis is connected to a separate safetyground.
Only fuses with the same required current, voltage rating, and specified type (normal blow, time delay, etc.) should beused. Do not use repaired fuses or short-circuited fuseholders. To do so could cause a shock or fire hazard
Do not operate the power amplifier in the presence of flammable gases or fumes.
Operating personnel must not remove the exciter cover. Component replacement and internal adjustments must bemade only by qualified service personnel.
The type N output connector carries dangerously high RF voltages which present a shock and burn hazard.operate this excitor with out the out put connector properly terminated in either an adequately rated load or antenna.
NEVER
Page 4
MONAURAL
OPERAT ION
Audio Input Impedance:
Audio Input Level:
Audio Frequency Response:
Total Harmonic Distortion:
FM S/N Ratio (FM Noise):
Asynchronous AM S/N Ratio (AM Noise):
Synchronous AM SIN Ratio (Incidental AM Noise):
600 ohms, balanced
+10 dBm (6.93 volts peak-to-peak) at 600 ohms for75 kHz deviation
+/-0.5 dB; flat or 75 microsecond pre-emphasis, 20Hz to 15kHz (other time const. available)
0.15% max.; 20 Hz to 15 kHz
70 dB min. below 75 kHz deviation at 400 Hz,measured within a 20 Hz to 15 kHz bandwidth with75 microsecond de-emphasis
60 dB RMS. below carrier; reference: 100% AMmodulation, at 400 Hz with 75 microsecond de-emphasis, no FM modulation
57 dB below carrier; reference: 100% AMmodulation, full power at 400 Hz with 75uS de-emphasis, FM +/- 75 kHz, 400Hz
Specifications
ENV I RO NM ENT
Altitude: Ambient Temperature0-10,000 ft -10 to +50 oC
WIDEBAN D
OPERAT ION
Inputs:
Input Level:
Wideband Amplitude Response:Composite Unbalanced 10k OhmsSCA 1 Unbalanced 10k Ohms
1.25 V RMS. (3.54 volts peak-to-peak) for 75 kHzdeviation
+/-0.5 dB, 20 Hz to 100 kHz
G ENERA L
Rated Power Output:
Power Consumption:
Frequency Range:
Frequency Control:
Frequency Stability:
Output Impedance:
Output Connector:
VSWR:
Modulation Type:
Modulation Capability:
Multi-Meter Indication:
Harmonic Attenuation:
25W, 50W, 150W, 300W
150 W (for 50W model)
87.7 to 108 MHz, in 200 kHz steps (other step size toorder)
Phase locked loop frequency synthesis from highstability master oscillator
+/- 1.2 kHz
50 ohms
Type -"N" female
1.5:1 for full power, derate to 0 at inf.
Direct carrier frequency modulation
To 100 kHz deviation
Deviation, Forward Power, Reverse Power, Final I & V
-70 dB, min.
1
45
Rear panel layout
8 7 6
5
1 2
3 4
Page 6
Front panel layout
. DEVIATION
2 3
8
AC IN
SCA
FUSE
RF OUTPUT
FINAL CURRENT
FINAL VOLTAGEFORWARD POWER
REVERSE POWER
ADJPOWER
OFF
OPERATE
REMOTE OFF
FAULT
DRIVE LOW
FM Series
PTEKFM25E
DEVIATION
3025201510
5
OUTPUT POWER W (REV X0.1)
4.040
3.030
2.020
1.0100
0 AMPS
PTEK
VOLTS
DEVIATION kHz
100
755025
ON
REMOTE
PWR PWR
VOLTAGE
FWD REV
OFF
CURRENTFINAL
MONO IN600 OHMS
RAISE
LOWER
GAIN
GAIN
GAIN
COMPOSITE
10MHz 1MHz 100kHz
FREQUENCY
Key Element Description
1 AC IN & FUSE 110 VAC input and Fuse 10A
2 COMPOSITE Unbalanced wide band composite input
3 SCA Unbalanced wide band input
4 RF OUT TYPE N RF Output
5 FREQUENCY SELECTION Set switches for frequency selection (only takes effect when unit is switched
from off to on)
6 Accessory connector Connections for; Remote off and DC indications of Forward Power, Reverse
Power, Final Voltage, Final Current and Deviation.
8 SERIAL NUMBER Serial number for reference purposes
Page 7
Key Element Description
1 METER Indicates Forward Power, Reverse Power, Final Voltage, Final Current and
Deviation
2 OPERATE Switch and
Indicator
This switch sets the FM Broadcast Amplifier to the Operate Mode; 110 VAC is
applied to the line transformers and this amber indicator is lit.
3 REMOTE OFF Indicator This red LED indicator is lit when the FM Broadcast Amplifier remote off
terminals (rear panel) are open circuit.
3 DRIVE LOW Indicator This red LED indicator is lit when the FM Broadcast Amplifier can not make
the power requested, because for example low drive power.
5 FAULT Indicator This red LED indicator is lit when the FM Broadcast Amplifier is in a fault
condition. This can be for one or combination of the following:-
Over drive, High supply Voltage, High load VSWR, Over temperature.
6 Meter Select Switch This switch selects one of the following to be presented on the meter (1):-
Forward Power, Reverse Power, Final Voltage, Final Current and Deviation.
7 ADJ POWER control This control adjust the output power from rated full power to less than 50%.
8 Ventilation Filter This provides for filtering the environmental air as it is drawn into the cabinet
by the internal fan (not used on FM10E).
Refer to the Table below for the following description. The installer should assure the ac line voltage is turned OFFbefore performing this procedure. The electrical connections are installed at the Exciter rear panel.
Installation-Electrical
Page 8
RG8 TO ANTENNA/PA
PART OF USER SUPPLIED REMOTE CONTROL
BALANCED MONO IN
OR (NOT BOTH)
FROM STEREO ENCODER OR STL
AC IN
SCA
FUSE
RF OUTPUT
ON
REMOTE
PWR PWR
VOLTAGE
FWD REV
OFF
CURRENTFINAL
MONO IN600 OHMS
RAISE
LOWER
GAIN
GAIN
GAIN
COMPOSITE
10MHz 1MHz 100kHz
FREQUENCY
Refer to the Table below for the following procedure.
Turn-On Checkout
Page 9
Stereo pilot level adjustment
With Stereo encoder (optional)connectedto composite input, adjust composite gaincontrol to give deviation meter readingshown (aprox 7.5kHz)
Page 10
Frequency Selection
10s MHz Switch
“0” is 10 (100MHz)
PLEASE NOTE, FREQUENCY CHANGESSHOULD BE MADE WITH THE UNIT TURNED
OFF
100kHz Switch1MHz Switch
Example Shown 104.5MHz
Reading the front panel meter
300250
100
020015050
50 75251000
DEVIATION kHzAMPS VOLTS(X10)
52.5100
7.5
PTEK
POWER Watts
300250
100
020015050
50 75251000
DEVIATION kHzAMPS VOLTS(X10)
52.5100
7.5
PTEK
POWER Watts
300250
100
020015050
50 75251000
DEVIATION kHzAMPS VOLTS(X10)
52.5100
7.5
PTEK
POWER Watts
300250
100
020015050
50 75251000
DEVIATION kHzAMPS VOLTS(X10)
52.5100
7.5
PTEK
POWER Watts
Forward Power
The forward power reading is amount of power going to theantenna. The example shown is a reading of 250 Watts. Thissetting can be changed with the front panel raise lowerswitch and should be set to the licenced power output (see“calculation transmitter power setting”).
Reverse Power
The Reverse power reading is amount of power returningfrom the antenna. The example shown is a reading of 2.5Watts. A correctly matched antenna should not return anypower back to the transmitter. The ration of Reverse Powerto Forward Power in this example 2.5/250 would give areturn loss of 1% or -20dB this would classified as a goodantenna. Reverse Powers approaching 10% will cause thetransmitter to reduce the output power (See antenna VSWREffects)
Final Voltage (V)
This is the voltage applied to the output amplifier stage. Theexample shown is a reading of 48 Volts. Used in conjunctionwith the final current reading will give an alternate methodof measuring output power. (Output power = V*I*0.7). 0.7is the efficiency of the output power amplifier.
Final Current (I)
This is the current consumed by the output amplifier Finalstage. The example shown is a reading of 8 Amps. Used inconjunction with the final Voltage reading will give analternate method of measuring output power as describedabove. This reading will change with output power setting,also antenna match will give different results.
FINAL CURRENT
FINAL VOLTAGE
FORWARD POWER
REVERSE POWER DEVIATION
Use the range selection switch(shown Left) to select the meterrange
Continued over
300250
100
020015050
50 75251000
DEVIATION kHzAMPS VOLTS(X10)
52.5100
7.5
PTEK
POWER Watts Deviation
This is the deviation in kHz caused by the program audio tothe carrier. The meter is peak reading and will vary inaccordance with the program (music speech etc.) The peaksshould not be more than 75kHz as indicated in this example.
Exciter Power Output Vs VSWR
0
50
100
150
200
250
300
350
1 1.1 1.2 1.3 1.4 1.5 1.6 1.7 1.8 1.9 2Antenna VSWR
Pow
er W
atts
Power Output FM250EPower Output FM150EPower Output FM50EPower Output FM25E
C52
The transmitter frequency should be checked at lease once every 5 years. If the frequency offset is greater than +/- 1.5kHz,adjustments can be made by tuning C52; see diagram for location.
Frequency Adjustment
A qualified service technician should make adjustments. Alternatively the unit can be returned to the factory for service.
Circuit Description General The FM250E is housed in a 3U (5.25”), 19” rack-mounting case. Internally there are 4 PCB assemblies and 2 cased power supplies. Functional Two 24V power supplies are connected in series to provide 48V for the power amplifier and 24V of the exciter and fan. Audio inputs (SCA Composite and Mono) are connected directly to the exciter board, premphasis is applied to the mono channel only. These input are then summed together and feed to a veractor diode used to tune the VCO (voltage controlled oscillator). A sample of the VCO’s output frequency is used by a synthesizer to compare again a reference oscillator. This generates an error voltage which is used to tune additional veractor diodes in the VCO to maintain a constant frequency. The main output from the VCO is amplified up to 25W. The output from the exciter board is used to drive the power amplifier to 300W. Integral to the power amplifier is a harmonic filter used to reduce harmonics generated in the power amplifier to acceptable levels. This output is then feed back to the exciter board and on to the output connecter via a forward and reverse power detector. The exciter board also contains control circuitry, which levels the output power to a level set by a reference voltage. The detected forward power and reverse power are summed and compared to the reference voltage. The gain of the reverse power path is 10 times that of the forward power. This ensures that should the load be remove the forward power will be reduced to a safe level. The reference voltage used by the control circuit is generated by a microprocessor. This value can be changed by using the up/down control on the front panel or by remote contact closure from the rear panel accessory connectors. The microprocessor also feeds the frequency information to the synthesizer. Metering on the from panel is a multimeter, each function is selected by a rotary switch. The voltages for Current and voltage are provided by the PSU metering board, forward and revere voltages by the synthesizer board. All these voltages are also connected to the rear panel for remote metering. Mounted on the exciter board is a magnetically latched relay used for remote on/off functions. This requires only a momentary contact closure for either on or off. Cycling the AC power will not change the state of this relay.
FCC Compliance statement
THIS DEVICE HAS BEEN VERIFIED TO COMPLY WITH PART 73 OF THE FCC RULES.
Page 11
Pos Function
1 Remote on; Momentary ground to turn the unit on.
2 Remote off; Momentary ground to turn the unit off.
3 Forward Power DC indication 2.4V=12W
4 Reverse Power DC indication 2.4V=1.2W
5 Final Voltage DC indication V=Vsupply/10
6 Final Current 1A=0.1V
7 Raise Ground to Raise Output Power
8 Lower Ground to Lower Output Power
9 600 ohms balanced mono input
10 600 ohms balanced mono input
FM25E FM50E FM150E
Power
Output
(Watts)
Efficiency
(%)
Power
Output
(Watts)
Efficiency
(%)
Power
Output
(Watts)
Efficiency
(%)
25.0 52% 50.0 48% 150.0 57%
22.5 49% 40.0 42% 120.0 51%
20.0 47% 32.0 38% 96.0 45%
17.5 46% 25.6 33% 76.8 40%
15.0 44% 20.5 30% 61.4 35%
12.5 42% 16.4 26% 49.2 32%
10.0 33% 13.1 23% 39.3 28%
Efficiency V Output Power
Accessory connector
CA 95124
SAN JOSE
1814 SCHOOLDALE DRIVE
PTEK
10/27/2003
A
1OF1
C
SHEETSCALE
REVDWG NOFSCM NOSIZE
A
B
C
4 3 2 1
C
B
A
1234
BLOCK DIAGRAM
5
5
4
4
3
3
2
2
1
1
D D
C C
B B
A A
NOT USED ON EXCITERS
NOT USED ON EXCITERS
110853 <RevCode>
Schematic PA 300W 88 to 108MHz
B
1 2Monday, March 08, 2004
Title
Size Document Number Rev
Date: Sheet of
AGC2
AGC1
AGC1
AGC2
IPARF
IPARF
44V
44V
C430.01u
R1100
PRINTED
Q1 MRF150
R11100
Q2MRF150
C3639p
C862p
R12100
C31 0.01u
R20
470
C1224p
R21 10k
C1447p
R622
PRINTED
T2
PCB TRFMR
1 5
4 8
C471000p
R2100
L2
C3515p
C3415p
PRINTED
R4100
C150.01u
C4847u
C420.01u
D21N4148
C647p
R22100k
R5120
C947p
C32 0.01u
L3
C45
0.01u
T1
15
6
48
C3739p
C4633p
C71000p
Q3MRF171
C3947u
J12
CON20
1234567891011121314151617181920C44
0.01u
C160.01u
C1047p
L1
L4
D1
1N4148
PRINTED
R13100k
C50.01u
C20.01u
C3315p
C3839p
R7120
C1147p
C27120p
L5
C30 0.01u
R9100
R3100
R10100
44V IN
FWD PWR
RF OUT
REV PWR
RF IN
REV PWR
FWD PWR
5
5
4
4
3
3
2
2
1
1
D D
C C
B B
A A
REV PWRFWD PWR
To Front Pan Metering
Current & Voltage Metering
B
1 1Monday, January 09, 2006
Title
Size Document Number Rev
Date: Sheet of
0V IN
24V
24V
J1
12
12
R11 10k13
2
MTG21
C3 1000p
MTG11
R10 0.01
R52.4k
+
-
U1A LM324
3
21
411
R62.4k
R9 100
R8
4.7k
R12.4k
J2
CON14
123456789
1011121314
J4
12
12
C21000p
R4
2.7k
J3
CON14
123456789
1011121314
C10.01u
R7
3.3k
R3
10k
13
2
R22.4k
5
5
4
4
3
3
2
2
1
1
D D
C C
B B
A A
DOWNUP
110849 A
PCB ASSY FRONT PAN METERING
A
1 1Monday, March 08, 2004
Title
Size Document Number Rev
Date: Sheet of
SW112
123456
789
10
11
D1
OUT OF RANGE LO
SW2
21 3
D2
OUT OF RANGE HI
D3
REMOTE OFF
J1
1234567891011121314
A
M1
METER A
5
5
4
4
3
3
2
2
1
1
D D
C C
B B
A A
48V IN +
48V IN -
48V OUT+
48V OUT-
24VPSU
24VPSU
24V+24V+ 24V-24V-
48V +
48V -
24V +
EXCITER 88 to 108MHz
PSU METERING
FRONT PANNELMETERING
COMPOSITE IN
SCA IN
RF OUT
REMOTE ONREMOTE OFF
FWR PWR
FINAL VOLTAGEREV PWR
FINAL CURRENTRAISELOWER
MONO IN BALANCEDMONO IN BALANCED
AC INLIVE
AC INNeutral
AC INNeutral
AC INLIVE
<Doc> <RevCode>
<Title>
D
1 1Monday, March 08, 2004
Title
Size Document Number Rev
Date: Sheet of
J1
1234567891011121314
D1
11
J1
123456789
1011121314
J2BNC
1
2
J3BNC
1
2
J1
1234567891011121314
J4TYPE N
1
2
D2
JP1
1 1
J1
1234567891011121314
11
11
11
11
JP1
1 1
J5REAR TERMINAL BLOCK
12345678910
JP1
1 1
JP1
1 1
J6PLUG AC MALE
1 2
3
11
11
11
11
AC ON
1 2
11
FAN 24V
1 2
11