Carrier Current

Radio Systems is the nation's primary provider of carrier current transmitters, AC line couplers, and accessories for college and institutional on-campus AM radio stations.

Carrier current is the legal, fast and inexpensive route to start a radio station for your organization.

TR-6000 Transmitter
A solid state, variable power, 10 watt digitally-synthesized AM transmitter with internal audio limiter and detector circuitry.

Radio Systems' TR-6000 represents a leap forward to the new Millenium in low-power AM RF design.

The successor to the industry-standard TR-20, the TR-6000 features numerous improvements in both audio quality, efficiency and technical specifications.

This solid state, 10 watt design is based on class D amplification, so the transmitter runs cool to the touch, even at full power. And, output efficiency is quadrupled, up to 80%, over its predecessor.

New features abound, as well, including remote control capability, a front panel power and audio VU meters, headphone monitor, and efficient, flat-pack design that can be easily rack-mounted. There are even multiple TXCO oscillator and external synchronization options.

Maximum Modulation
Output Circuitry Monitoring

AM radio is always fighting high back-ground noise levels, so maximum audio modulation is important for the best possible signal to noise ratio.

The TR-6000 has an internal 100% peak modulation limiter which automatically controls the transmitter gain to stop over-modulation distortion. The limiter has a full 40 dB gain reduction range. Limiting action is controlled by input gain level setting.

The TR-6000 is a totally solid state unit and benefits from the extended frequency response and stability of transistors through the final output stage.

Extremely dependable and long life operation is achieved by utilizing Class D circuitry. This allows the TR-6000 to be used in facilities where the only available power sources are batteries or solar power.

The result is a highly efficient, cool-running unit.

The TR-6000 output can be monitored through its built-in audio detector circuit. These components effectively comprise a miniature radio whose audio output is provided on a phone jack on the side of the transmitter. Headphones can be utilized for on-site monitoring, or the signal can be wired to remote amplifier.

Because the detector monitors the signal envelope at the final output of the transmitter, performance of the entire audio chain can be evaluated.


R.F. Power Output

Adjustable to 10 watts

Type of Emission

Amplitude Modulation (A3)

Frequency Range

500 kHz to 1.7 MHz

Frequency Stability

± 20 Hz (-20° to +50° C)

Carrier Shift

2% maximum

Harmonic Attenuation

35 dB or better


-55 dB below 100% modulation

Audio Input (for 100% modulation)

-50 dBm minimum

Frequency Response

20 Hz to 15 kHz ±1.0 dB maximum

Audio Distortion

Less than 2% @90% modulation

Modulation Monitoring

LED Power Meter, Built-in envelope detector

Modulation Limiting

Built-in 100% peak modulation limiter, 40 dB gain reduction

Power Consumption

48 watts at 24 vdc


w-15" h-6" d-2"


4 lbs.


1 year - parts and labor

CP-15 Coupler

An antenna matching unit design specifically for loop antennas with built-in reactance compensation.

Radio Systems' CP-15 Coupler is a unique antenna matching device with sophisticated, specialized circuitry for low power AM broadcasting. Existing electrical wiring is frequently used as an antenna for low power systems. This wiring, not intended for energy at RF- frequencies, present a hostile environment for radio equipment. The CP-15 Coupler has been designed to efficiently transfer RS energy into these antenna systems and protect the transmitter unit.

A specially developed, two stage system is employed for impedance compensation. Two broad band transformers are combined to provide a total of 15 impedance settings. A decade capacitor switching system is also incorporated to provide reactance correction and cancel any antenna grid reflection of radio energy.

The proper combination of impedance and reactance settings are determined throughout the internal bridge circuit. The meter allows the "nulling" of reflected power and maximization of transmitter to antenna energy transfer. In the match mode, 90% of the transmitter power is automatically "dummy loaded" to protect the transmitter circuitry. The three output circuits provided are fuse protected by high voltage, high pass capacitors.

Direct SWR Readings

Improved Matching

The "Phase II" coupler has a bridge and meter circuit which can be used to directly read the standing wave ratio of the carrier signal. Transmitter to antenna match can be quantitatively evaluated and a direct ratio calculated.

The CP-15 two stage coupler, with integral reactance and impedance compensation, provides an exact match into a wide variety of antenna systems. This efficient energy transfer insures maximum signal strength and radio coverage while protecting the transmitter from damage due to high VSWR conditions.


Power Input

20 watts RMS maximum

Input Impedance

50 ohms unbalanced

Output Impedance

1 to 50 ohm in 15 ranges with built-in capacitance decades

Matching Circuit

Two stages: multifilar wound ferrite transformers


VSWR bridge, forward and reflected readings

AC Line Connection

500V maximum, line to line and ground


W-9" H-9" D-3"


5½ lbs.


1 year - parts and labor

SP Series Splitters
RF transformer type, low loss splitters, available in 2 to 8 output configurations.

Radio Systems, Inc.      601 Heron Drive      Logan Township, NJ 08085      Phone: 856-467-8000      Fax: 856-467-3044