This is the Gates/Harris Radio Section of
The Broadcast Archive

Maintained by:
Barry Mishkind - The Eclectic Engineer
Last Update 6/6/12

50,000 Watt Transmitters

  Gates Radio Co
Quincy, IL


  Harris Broadcast
Quincy, IL / Mason, OH

Harris purchased Gates radio in 1957, but kept the Gates name and logo until the 1970s.
Transmitters built by Harris were still essentially "Gates design."

BC-50B   1957-1959

The first 50 kW unit by Gates Radio.  1957.

The first 50 kW built by Gates was a design adapted by Stan Ponte from the GE 50 kW transmitter. 

Only three of the BC-50B's were built. They went to: XET, Monterrey, Mexico, Radio Rumbas in Caracas, Venezuela, and CKVL, Montreal, Canada.

According to Larry Cervon: "Parker Gates didn't want to build this transmitter - he was not a risk taker." Gates felt there was no sure profit in building such a large transmitter as the 50B. But with an order in hand, he was convinced by Cervon. It took a year to construct.


BC-50C   1960-1965

A Catalog page from Gates showing the BC-50C, built from 1960 to 1965.  This model removed the "spare" PA tube.  This may have had a home at KCUL in Ft Worth, TX

VP-50   1965-1972

KDAY picture from Gates Catalog 98

Built from 1965 to 1972   at least eight were built.

The VP-50 was "Vapor Cooled" transmitter, this was a real effort to get some of the "Big Iron" business. 

According to the Gates catalog, The first one went to KDAY/1580, Santa Monica (Los Angeles Tx site), CA.

WWVA's VP-50 being delivered.


MW-50  1972-1978


Built from 1972 to 1978, the MW-50 was a Pulse Duration Modulated (PDM) transmitter. It used five tubes,

WJR, Detroit, WBBM, Chicago


MW-50A   1978-1981


Built from 1978 to 1981, the MW-50A had a tube-type damper diode. Also, the Modulation Enhancer (ME-1) was built into the transmitter, as well as a modulation "tracker" to keep modulation constant at different power levels.
The transmitter employed Pulse Duration Modulation. One of the 4CX-1500A tubes served as a driver for the 4CX-35000C Modulator tube. The other 4CX-1500A tube was the driver for the RF Output 4CX-35000C tubes. The rest of this transmitter was solid state - in fact, later versions of this MW-50 Transmitter replaced the 4CX-1500A modulation drive tube with a solid-state amplifier, leaving only the rf driver and the two 4CX-35000C tubes.
WBZ Boston was one user.

MW-50B   1981-1984

Built from 1981 to 1984, the MW-50B used three tubes, as the damper diode was changed to a solid-state rectifier.  The modulation driver went from tube to solid-state.

MW-50C and MW-50C3   1984-1991

Built from 1984 to 1991, the MW-50C and MW-50C3 versions were a transition to the DX Series. The transformer input was removed the and replaced with a differential balanced input, significantly reducing overshoot and distortion levels.


DX-50    1991-2003


Built from 1991 to 2003.  The first unit went to KFBK in Sacramento, CA
This is a Harris Patented system, using a large quantity of plug-in modules. Each generates RF at a different modulation level; incoming analog audio is broken down into digitized data, then it is used to drive the various modules at the varying levels needed to have an amplitude modulated output. This transmitter has an overall efficiency (power line in versus RF out) of around 85 to 90%

3DX-50   2003-present


Built stating in 2003

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