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Radio Broadcast Technical Consulting and Sales
10032 Island Drive, Brainerd, MN  56401
Phone: 218.829.1326   

Gates BC-1G Transmitter Repair

M. W. Persons and Associates, Inc.

This is a Gates/Harris BC-1G 1000 Watt AM Radio Broadcast Transmitter. 

It was originally put into service in 1964 and came into the shop for refurbishing.

Rated at 1100 watts maximum, there is a power cutback to 250 watts.

It runs on 240 VAC/30 Amperes AC input.

Manufacturers specs show it capable of going from 540 Kc to 2000 Kc.

Some amateur radio operators are using this model on 160 and 80 meters. 

The metering panel is well laid out and very nice for watching its operation.  

The RF tube lineup is two 12BY7A in the RF oscillator section followed by two 807A in parallel driving two 833A power amplifier tubes.

The audio section has two 807A driving two more 807A, which in turn drive two 833A modulator tubes.

Currently, 833A tubes are selling for about $150 each while similar transmitters use 4-400 tubes at $400 each.  

This is an excellent robust design for radio broadcast service.

Audio frequency response is 30 Hz to 12,000 Hz +/- 1.5 dB.

The transmitter can be tuned to match 50 to 70 ohm loads or easily redesigned for other impedances.

A Gates sales brochure gives more details.   

The bottom of the transmitter shows solid-state rectifiers on the left, which was a new innovation back in 1964.

The orange colored high voltage transformer is connected to the diodes. 

The large black transformer on the right is the modulation reactor.  It was dipped in a heavy black paint to keep moisture out when it was manufactured.  It looks a bit wrinkled, but it always looked like that and is in perfect working condition.

Fully modulated, the four 833A tube glow brightly.  This is normal.
Oscilloscope displays show 100% modulation on the left and 120% modulation on the right.  These are actual measurements on this transmitter after refurbishing in our shop.

This transmitter was SOLD


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page last edited 03/06/2017