MT4 is accomplished by true FM transmitting. A variable gain cell amplifier is used for low distortion audio without clipping (less than 2%). Compression begins at 4.8 KHz and hard limiting will occur at a level of 5 KHz (factory set values). In hard limiting the modulation is held constant for input levels of greater than 30 DB. Unlike most transmitters today the MT4 uses a MOS FET for the final transistor. The MOS FET has a much lower noise floor (typically 3 times lower) and is not subject to thermal runaway as bi-polar are. The MOS FET used in the MT4 is capable of withstanding up to a 30:1VSWR. When configured for high power operation the MT4 is supplied with a multiple section low pass filter to suppress harmonics.
Power Supply
Voltages are decoupled in all stages to prevent noise pickup using ferrite beads for high frequency and capacitors for low frequency rejection. The circuit board also has copper ground planes on the top and bottom with multiple feed through points for excellent R.F. grounding.
MT 4
Comes mounted in an R.F. tight enclosure with feed through capacitors for both audio and power supply lines. The R.F. out is supplied to an SO239 connector for VHF and TYPE N standard on UHF. All units are factory tested and burned in to your specified frequency before shipment. Their 1-year warranty is our statement of commitment to quality.
Frequency Range
136-174MHz, 216-250MHz (VHF), 420-520MHz (UHF)
2 meters
220 MHz
440 MHz
Power Output
Low Power
2 watts
2 watts
2 watts
@ 13.8 V
High Power
15 watts
10 watts
5 watts
@ 24 V
High Power
30 watts
20 watts
10 watts
Power Requirements
Low Power
500 ma
500 ma
500 ma
@ 13.8 V
High Power
500 ma
500 ma
500 ma
@ 24 V
High Power
500 ma
500 ma
500 ma
Crystal Multiplication
12
18
24
Frequency Control:
Parallel resonant crystal (22 pf load) capacitance, HC-25/U holder. Proportional oven used in FCC type accepted units.
Output Amplifier:
MOS FET capable of withstanding 30:1 VSWR
Modulation:
Direct FM. Variable gain cell amplifier for audio compression and limiting with low distortion. Adjustable from 0-7 KHz.
Frequency Stability:
.0005% (-30c to 60c), .0001% with optional proportional oven
Harmonic Output:
Greater than 65 DB below rated output
Spurious Output:
Greater than 90 DB below rated output
Noise Output:
Greater than 90 DB below rated output in high power mode at 600 KHz from output frequency.
Audio Response:
Within 3 DB of EIS standard 6 DB / octave pre-emphasis from 300 Hz to 2700 Hz. Less than 2% distortion.
Duty Cycle:
Continuous, (all our products are rated for continuous commercial duty)
Emission Designator:
5 F 3
LOW NOISE MOS FET
TRUE FM
90% DUTY CYCLE
SHIELD OSCILLATOR / MULTIPLIER
STAGES
DOUBLE TUNED
CIRCUITS
PROVISIONS FOR INTERNAL CTCSS
Warranty
All ACS products are guaranteed in materials and workmanship for 1 year from the date of purchase. Please
contact us for complete details.
215-250 MHz