CONTINENTAL ELECTRONICS 417 B

GENERAL DESCRIPTION

Type 417B 50 kW HF AM Broadcast Transmitter

photo Continental Electronics 417 B

This transmitter is designed for operation in the International short wave broadcast band, and for communication service with frequency shift keying. The Type 417B is manually tuned over the frequency range from 3 to 30 megacycles. Utilizing high-level plate modulation, the Power Amplifier uses a single type ML-6697 air cooled tube which provides high efficiency, increased reliability and ease of servicing as compared to multiple-tube power amplifiers. Light weight, low cost power tubes are operated at 50% or less of their maximum ratings for increased reliability. Solid state rectifiers are used in all power supplies.

ADDITIONAL CAPABILITIES
The Type 417B is designed as two separate units: the audio modulator system, and a complete radio frequency system. The RF system may be operated as a FSK communication transmitter independently of the modulator.

RF CIRCUITS
Any appropriate master oscillator can be used to excite the Type 417B. The first and second RF amplifier stages are series-fed circuits, and are tuned through a gear train from a single motor. The inter-stage coupling between the intermediate power amplifier and the power amplifier consists of a motor driven Pi network. The PA employs broad band bridge neutralization.

OUTPUT TUNING
The output network consists of a parallel resonant circuit tuned by motor driven vacuum capacitors. Motor operated loading is accomplished by varying the coupling between the balanced output links and the parallel resonant circuit inductor. Four sets of inductors are provided for band changing.

AUDIO CIRCUITS
First and second audio stages are operated in Class A push-pull. The driver stage is a cathode-follower employing four tubes in a push-pull parallel configuration. The high-level modulator operates in Class B push-pull for a 40 kw output.

POWER SUPPLIES
All power supplies utilize solid state rectifiers, eliminating warm-up time and improving transmitter operation in areas of temperature extremes.

COOLING
Transmitter is air cooled, with air intake from the bottom/back.

TECHNICAL SPECIFICATIONS
Audio Input Impedance	150/600 ohms
Audio Input Level	+10 ±2 dbm
Audio Frequency Response	±1.5 db, 50-7500 cps
Hum and Noise	55 db below 7500 cycles (95% modulation)
Carrier Shift	Less than 3%
Type of Modulation	High level plate
Frequency Range	3-30 mc
Type of Emission	A3
RF Output Impedance	150-600 ohms balanced
Power Output Capability	55,000 watts
Power Source	460 volts ±5%, 50-60 cps, 3 phase, 3 wire
Power Consumption	0% modulation 95 kw 30% modulation 110 kw 100% modulation 145 kw
Power Factor	0.9
Specifications may change without notice

TUBE COMPLEMENT
RF stages		AF stages and modulator
Number	Type	Number	Type
1	ML-6697	2	ML-6427
1	4CX5000A	4	304-TL
1	4-125	2	4-125A
1	6146	2	6146

THIS TYPE OF TRANSMITTER IS INSTALLED IN THE FOLLOWING COUNTRIES
	ITU	Country	ITU	Country
	HOL	NETHERLANDS	G	UNITED KINGDOM
	USA	USA	VEN	VENEZUELA