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Armstrong's Latest Contribution
A NEW PHASE-SHIFT MODULATOR
Ised Exclusively in the New QHJ DL Line of FM Broadcast Transmittei
SIMPLER-MORE EFFICIENT
MAJOR E. H. ARMSTRONG — the inventor of FM — has recently developed a new phaseshift modulator circuit which REL has now incorporated in all of the new DL line of FM broadcast transmitters — now available for early delivery in five power ratings from 250 W. to 50 KW.
Remember — when you deal with REL — you deal with FM's Pioneer Manufacturer — with experience and knowledge gained from having built and put in operation — more FM broadcast transmitters than all other manufacturers combined.
The general overall characteristics of DL FM transmitters are:
* OPERATING FREQUENCY: Available to operate on any predetermined frequency from 40 to 50 inc. The exact frequency must be specified when the order is placed.
* FREQUENCY STABILITY: These trans' miners are guaranteed to maintain their
frequency within less than 200 cycles of the assigned frequency. The frequency is directly controlled by a single crystal, without the use of complicated mechanical or electronic devices,
* FIDELITY: The overall response is within plus or minus 1 db from 30 to 15,000 cycles.
* DISTORTION: The measured r.m.s. harmonic distortion is less than 1% for all signal frequencies between 50 and 15,000 cycles at ± 75 kc. swing, (100% modulation) AND IS LESS THAN .2% FOR FREQUENCIES FROM 400 to 15,000 CYCLES.
* NOISE LEVEL: The signal-to-noise ratio is better than 70 db, measured at the output of a monitor receiver. This is an unweighted measurement, with 150 kc. maximum swing, and includes hum.
* INPUT: The audio input to the transmitters is zero level, 500 ohms, 6 milliwatts.
* ECONOMY: New Type 558 Modulator employs only 28 small tubes from program input to operating frequency — affording lowest possible tube cost; for example, a complete set of tubes for the new catalog 518 DL 1000 W. transmitter including modulator is only $238.
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Illustrating a new, exclusive REL feature: Type 558 modulator panel hinged to swing out of its cabinet — making all parts quickly and easily accessible for adjustment and maintenance,
The new Type 558 modulator — built < rectly into the 250 and 1000 watt bai transmitter units, which are used to dri amplifiers of all higher powers.
Write for booklet describing this new DL line of FM transmitters.
RADIO EN
35-54 36th Stree
G LABORATORIES, INC.
53
long Island City, New York 42
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Pacific Coast sales offices: 5334 Hollywood Blvd., Hollywood, Cal 420 Market Street '
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