10,000 Watt 2-22 MC Transmitters

photo Gates HF-10 New and Modern High Frequency Transmitters for 10 kw, available in several models for telephone, telegraph and broadcast service.

These excellent Gates transmitters have already established an enviable reputation in both private and government communications throughout the world. - Designed to operate in world-wide climates and for the rigorous demands of continuous duty. - Available in five models to fit all requirements of voice or broadcast quality, telegraph only, or combinations of modulated and high speed CW service.

Carrier frequency change may be made in a matter of seconds by a combination of continuously variable tuning plus "latch on" tank coil assemblies. - New tube complement means lower tube cost and longer tube life.

Every modern innovation known has been applied to the design of these fine Gates transmitting power plants. Though up to the minute in design, Gates engineers have omitted any mechanical arrangements that are difficult to service, repair or maintain. Gates HF-10 series high frequency transmitters are rugged, heavily built, straightforward designed equipments that will please a world-wide engineering clientele.


MODELS AVAILABLE for 10 kw service are listed below. Whether the need is for voice quality modulation, broadcast quality, telegraph or combinations of telegraph and telephone, you will find a model exactly as required. Telegraph models will key with perfect square top wave form up to 400 WPM, and excellently up to 600 WPM. Frequency shift keying is adaptable to all models.

TUBE COMPLEMENT Particular note should be made of the 3X2500F3 tubes used in all models in the radio frequency and modulator stages. These low cost, long life tubes mean much in high operating efficiency and low hourly operating cost.

BAND CHANGING is quick and effective. All circuits are continuously variable and tuned from the front panel-with exception of the final tank coil. The Gates "latch on" system allows fast changing of this coil and completely eliminates complicated and costly tuning mechanisms. Four final tank coils are provided to cover the range from 2 to 22 megacycles. Pi-network tuning is also continuously variable.

AUDIO has four stages, with abundance of drive and modulation capacity. Broadcast models employ both modulation transformer and reactor, while voice models are equipped with the new and exclusive Gates designed Hi-cap modulation transformer. This eliminates the modulation reactor-and yet, adds to modulator efficiency at voice frequencies.

POWER SUPPLIES are generous in both size and number. Main supply is full wave, three phase, utilizing either six 8008 or 673 tubes, depending on model selected. Separate supplies are incorporated for low voltage and bias circuits. No combination filament transformers will be found in these transmitters, i.e., no more than one secondary winding to a transformer.

PROTECTIVE DESIGN is very complete. It includes primary circuit breakers in all major circuits and individual supervisory relays in all overload circuits such as RF driver, audio driver, final amplifier, modulator, air failure and exciter failure. Time delay, door interlock and pressure type blower air interlock protective equipment are all standard equipment.

RECYCLING is part of the HF-10 transmitter design. If, for any reason, the carrier should go off the air, the transmitter will automatically turn itself back on four times. Thus, in case of a static discharge, such as across the base of a tower, the transmitter will automatically turn back on.

COOLING is provided by one large squirrel cage blower which sends a torrent of air to the four 3X2500F3 tubes - with excess air blowing into the transmitter proper. A diaphragm air pressure switch protects the tubes against air failure, and even a clogged air filter will activate the diaphragm pressure switch. An additional small blower feeds a small stream of air on the base of each high voltage mercury vapor rectifier tube.

LOADING from the push-pull power amplifier is balanced and will match from 300 to 800 ohm lines. Veeder counter dials on the variable pi-network coils allow accurate logging for frequency change.



All models consist of three cubicles or cabinets which bolt together easily after unpacking. At the bottom of each cubicle are large barrier terminal strips which transfer the wiring from cubicle to cubicle, eliminating any cabling after receiving. Full size front and back doors are provided for the two outside cubicles. Layout design is such that the attendant may walk inside the back-rubber mats are provided. Such refinements as automatic internal lights that turn on when the back door is opened, and utility receptacles for drop cords or soldering iron are standard equipment.

Floor space for the three cubicles or entire transmitter is 125" wide and 49" deep, exclusive of door swing. Broadcast and voice models have external modulation transformer, reactor and power transformer. Telegraph models have the power transformer self-contained in the left cubicle. Heavy cold rolled furniture steel, both resistance and seam welded, with more than ample re-enforcing, is fabricated into the elaborate cabinet section of these Gates transmitting plants. Cabinet is prime coated, then hot sprayed, after which it is hand rubbed. Standard color is gray. All hardware is in chrome, nickel or natural brushed aluminum. Design meets regulations of all countries under the heading of "good engineering practice."


Five Models To Select From

HF-10B, identical in all respects to the HF-5B but providing 10,000 watts output from 2-22 mc with high level modulation and uniform audio frequency response within 2 db between 30 and 10,000 cycles. For international radio broadcasting at high frequencies, no finer 10,000 watt equipment has ever been constructed. Uses the famous 3X2500F3 tubes with thoriated tungsten filaments in both power amplifier and modulator sockets.

HF-10BX, a 10,000 watt radio transmitter identical to the HF-10B but having added a high speed electronic keyer, providing a high quality 10,000 watt telephone and telegraph transmitter for use between 2-22 mc.

HF-10C, a 10,000 watt communications type telephone transmitter with its audio components designed for voice quality transmission only, and in other respects identical to the HF-10B transmitter. For international telephone communications no finer 10,000 watt radio transmitter has ever been constructed.

HF-10CX, an identical transmitter to the HF-10C but with high speed electronic keyer added and providing a 10 kw telephone and telegraph transmitter.

HF-10TX, a telegraph transmitter producing 10 kw power over a wide band of frequencies between 2-22 mc. The high speed electronic keyer is part of the equipment.

Metering Individual meters provided for: Oscillator plate, First Int. Amp. Plate, Second Int. Amp. Grid,
Second Int. Amp. Plate, Third Int. Amp. Grid, Third Int. Amp. Plates (2 meters), Power Amp. Grid,
Power Amp. Plates (2 meters), First Audio Plates, Second Audio Plates, Third Audio Plates (2 meters),
Modulator Plates (2 meters), Filament Volts, Plate Volts. (Telegraph models have audio meters omitted.)
Frequency Range 2-22 mc
Power Output 10,000 watts carrier. Note-Under certain circumstances power output above 18 mc will be slightly lower
Output Impedance 300-800 ohms balanced
Frequency Stability 0.005%
Crystal Positions 4 (additional crystal provisions available on special order)
Audio Input 600 ohms; plus 17 dbm
Frequency Response Plus or minus 1.5 db, 30-10,000 cycles broadcast model;
Plus or minus 3 db, 150-4000 cycles communications model
Distortion 3% or less all frequencies between 50 and 7500 cycles for broadcast model;
10% or less between frequencies of 150 and 4000 cycles for communications model
Noise 60 db or better below 100% modulation, broadcast model;
45 db or better below 100% modulation, communications model
Power Consumption at 100% Modulation all models, approximately 31 kw, except HF-10TX, approximately 20 kw
Keying Speed 400 WPM with pure square top wave form. Higher practical keying speeds up to 600 WPM easily possible
Size 125" long, 78" high, 49" deep, with door swing front and back doors 40".
Size of largest cubicle 50" wide, 56" deep, 80" high.
Space required for external transformers, where used, 36" wide, 72" long, 36" high
Net Weight telephone models, 12,000 lbs
Gross Weight telephone models, 15,100 lbs
Cubage 342 cu. ft.
Specifications may change without notice

RF stages AF stages and modulator Rectifiers
Number Type Number Type Number Type
2 3X2500F3 2 3X2500F3 6 673
2 4-125A 4 845 4 8008
1 807 2 807

2 6L6 2 6J7


ITU Country
ITU Country