USER GUIDE
FEBRUARY, 2005
V2.1.4
PX50 FM STEREO TRANSMITTER
Copyright Ramsey Electronics, Inc. 2005, All rights reserved
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AGENCY CERTIFICATIONS AND USER INFORMATION
FCC ID: PF3PX50
Grantee Code: PF3
Equipment Product Code PX50
This unit complies with Part 73 and 74 of the FCC Certification/
Verification Standards for Licensed Broadcast Station Transmitters. This device complies with Part 15 of the FCC rules. Operation is subject to the following two conditions: (1) This device
may not cause harmful interference, and (2) this device must
accept any interference received, including interference that may
cause undesired operation.
This equipment has been tested and found to comply with the
limits for a Class A digital device, pursuant to Part 15 of the FCC
Rules. These limits are designed to provided reasonable protection against harmful interference when the equipment is operated in a commercial environment. This equipment generates,
uses, and can radiate radio frequency energy and, if not installed
and used in accordance with the instruction manual, may cause
harmful interference to radio communications. Operation of this
equipment in a residential area is likely to cause harmful interference in which case the user will be required to correct the
interference at his own expense.
IC:4318A-PX50
This unit complies with BETS-6 Technical Standards for Licensed
FM Broadcast Station Transmitters (Canada)
WARNING: Changes or modifications not expressly approved
by Ramsey Electronics, Inc. could void the user’s authority to
operate the equipment
MODEL: PX50
DESCRIPTION: Commercial FM Stereo Transmitter
590 Fishers Station Drive, Victor, NY 14564, (585) 924-4560
RAMSEY ELECTRONICS, INC.
www.ramseyelectronics.com
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TABLE OF CONTENTS
1.00 Introduction...........................................................................................................5
1.01 Checking the Contents...............................................................................5
2.00 Features ..................................................................................................................6
2.01 Continuous Monitoring ............................................................................6
2.02 Use It Anywhere In The World ...............................................................7
2.03 Cool Running...............................................................................................7
2.04 Variable RF Power Output.......................................................................7
2.05 Easy Installation ..........................................................................................7
2.06 Rock Solid Performance ..........................................................................7
3.03 PX50 Overview ......................................................................................................8
3.01 Front Panel ...................................................................................................8
3.02 Rear Panel ....................................................................................................8
3.03 Internal Layout ............................................................................................9
4.00 Installation and Initial Setup.......................................................................... 10
4.01 Licensed Operation................................................................................. 10
4.02 Unlicensed Operation............................................................................ 10
4.03 Rack Mount Installation......................................................................... 10
4.04 Primary Power.......................................................................................... 10
4.05 Secondary DC Power ............................................................................. 11
4.06 Audio Inputs ............................................................................................. 11
4.07 MPX Input .................................................................................................. 11
4.08 Pilot Output............................................................................................... 11
4.09 Antenna...................................................................................................... 11
5.00 Using the PX50 Front Panel Interface........................................................... 12
5.01 Navigation Control and Display .......................................................... 12
5.02 General Display........................................................................................ 12
5.03 Audio Display............................................................................................ 12
5.04 VSWR Display............................................................................................ 12
5.05 Temperature Display ..............................................................................13
5.06 Set Volume................................................................................................ 13
5.07 Set Modulation......................................................................................... 13
5.08 Set Audio Modulation Limiting (AML).............................................. 14
5.09 Set Frequency........................................................................................... 14
5.10 Set RF Output Power.............................................................................. 15
5.11 Set Stereo Mode...................................................................................... 15
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5.12 Set Station ID............................................................................................ 15
5.13 Set Auto Power ........................................................................................ 15
5.14 Set Power Fault........................................................................................ 16
5.15 Set Power Fault Timer............................................................................ 16
5.16 Set Test Timer........................................................................................... 16
5.17 Set Control Lock ...................................................................................... 17
5.18 Quiet Mode ............................................................................................... 17
5.18 Super User Mode ....................................................................................17
6.00 Appendix ............................................................................................................. 18
6.01 Appendix A: US Frequency Assignments........................................ 18
6.02 Appendix B: Troubleshooting............................................................. 19
6.03 Appendix C: Operating Temperature Characteristics.................. 21
7.00 Specifications ..................................................................................................... 22
8.00 Warranty .............................................................................................................. 23
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1.00 INTRODUCTION
The PX50 has been carefully inspected and packed by Ramsey Electronics, Inc. for shipping.
Upon receipt please check the carton and look for any visible damage and notify the carrier
immediately.
1.01 Checking the Contents
The PX50 FM Stereo Transmitter package includes the following:
1 PX50 FM Stereo Transmitter
2 110VAC EIA Power Cord
3 12VDC Connector Assembly
4 Operator’s Manual
Please check your package and contact Ramsey Electronics Technical Support if any items are
missing.
Ramsey Electronics, Inc.
Technical Support
590 Fishers Station Drive
Victor, NY 14564 U.S.A
(585) 924-4560
(585) 924-4886 Fax
TechSupport@ramseymail.com
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2.00 PX50 FEATURES
The PX50 is state of the art 50 watt FM stereo transmitter designed for commercial FM,
LPFM and international use over the frequency range of 87.5 MHz to 108.1 MHz. The
RF output level is continuously variable from 1 watt to 50 watts. The transmitter is
housed in a compact 2 rack-unit enclosure for easy installation.
Full front panel control and monitoring is provided by an easy to use navigation switch
matrix with intuitive 2 line 20 character vacuum fluorescent displays. These controls
and displays are provided for the following:
Frequency
Left/Right audio levels
Left/Right peak-hold meters
PLL lock
RF power output
VSWR
Amplifier temperature
Exciter temperature
Audio modulation
Audio modulation limiting (AML)
Stereo mode
Auto VSWR protection
Auto power leveling
Auto temperature protection
Power reduction on error
Power restoration timer
Test timer
Station identity
Control lock
2.01 Continuous Monitoring
The PX50 constantly monitors all of the critical circuits within the transmitter and makes
subtle adjustments to various circuit parameters depending upon frequency, temperature, power, audio level, and deviation - in short, it’s like having a station engineer constantly monitoring and adjusting on-the-fly!
Automatic VSWR protection automatically reduces power output until the VSWR problem is cleared. Likewise, if the power amplifier temperature exceeds 70° C, the transmitter will reduce power output until it cools down below 60° C. You can set automatic
Power Reduction On Error (VSWR & Temperature errors) to 85%, 75%, 50%, 25% or full
disable of the set power. Full power is restored when the error is cleared. You can also
set the Power Restoration Timer for the error testing time to match your specific site environment. If the error is cleared within this time, the transmitter is restored to full
power for unattended operation! Your station stays on the air, and needless trips to
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your tower site are eliminated!
2.02 Use It Anywhere In The World
We made the primary input power universal for virtually any location worldwide. Give it
anything from 85-264VAC between 47-63Hz, or 120-370VDC and you’re all set. It doesn’t get much easier than that! You can also run the PX50 primary power from 1214VDC. You can even provide 12-14VDC from a battery (or vehicle) and have automatic backup in case of a power failure! Your listeners will never miss a beat! Using it
out of the country with different frequency plans? No problem, with the 100kHz spacing, you are good to go with the PX50!
2.03 Cool Runing
A super quiet and high CFM fan is mounted inside the PX50 providing direct forced air
cooling to the oversized PA heatsink. Outside air is drawn in through the dual dust filtered front panel air inputs, which is routed through the power supply to the PA. Forced
air exhausts through the notched real panel. The result is an extremely quiet high efficiency cooling system that keeps your transmitter up and running even in the harshest
environments.
2.04 Variable RF Output Power
Need to throttle back your power to meet your ERP license limitations? Or want to use
the PX50 as a stand alone exciter? No problem. The PX50 RF output power is completely adustable from front panel digital controls, from 1W to full 50W power in 1W
increments!
2.05 Easy Installation
Installation of the PX50 is a breeze. A standard Type-N connection is provided for RF
Output. Balanced (XLR) left and right audio inputs are provided to properly interface
with any audio source you have. In addition, BNC SCA/Digital/RDS inputs are provided
along with a quick disconnect connector for a 12 VDC standby/back-up power input.
In short, connect your audio sources and antenna, power it up, set frequency and power
level via the front panel navigation switch matrix, and you’re on the air! It doesn’t get
any simpler! All of this in a compact 3.5” standard 2 rack unit case that runs a cool and
quiet continuous duty!
2.06 Great Sounding Rock Solid Performance
An 8 times oversampled stereo generator with true analog filters throughout assures a
clean, refreshing sound image while the RF transmitter chain employs generously rated
components for headache-free, long life. The result? You stay on the air while competitive transmitters would shut down!
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3.00 PX50 OVERVIEW
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3.01 Front Panel
1. 2-line vacuum fluorescent display
2. Power on/off switch
3. 5-way navigation switch matrix
4. Filtered forced air input, do not block air flow
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3.02 Rear Panel
1. Forced air exhaust port, do not block air flow
2. RF output, 50 ohm
3. Audio input left, 600 ohm balanced
4. Audio input right, 600 ohm balanced
5. MPX input, for SCA subcarriers or RDS data
6. Pilot output, 19 kHz
7. 12-14VDC secondary power input
8. Primary AC fuse
9. Secondary DC fuse
10. Primary AC power input, 85-264VAC, 47-63 Hz
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