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30L-1 Keying Instructions

The Collins 30L-1 is an American high-frequency linear amplifier that outputs approximately 500 watts when driven by a nominal 100 watt high-frequency transmitter or transceiver. Although designed to operate with vacuum tube radios, the 30L-1 is usable with modern transistorized transceivers with one caveat: the amplifier keying line has a peak negative voltage of 170 volts DC at approximately 75 milliamperes, while the typical modern radio is designed to control a much lower voltage. Fortunately, relay buffers are available to interface the 30L-1 keying line to a solid-state transmitter.

Things You'll Need

Amplifier interface buffer
Buffer instruction manual
Transceiver instruction manual
Ground wire
Buffer-to-radio cable
2 RCA male to RCA male cables

Instructions

- 1
  Unplug the amplifier power cord. Connect a ground wire from the station ground bus to the chassis ground stud of the interface buffer.
- 2
  Connect the buffer-to-radio cable to the "Radio" jack on the interface buffer. Connect the key and ALC lines of the cable to the transceiver. Refer to the radio manual if you need help finding the proper connections.
- 3
  Connect one RCA cable to the "Ant Relay" jack on the rear panel of the amplifier. Connect the other end of the cable to the "Amp" jack on the interface buffer.
- 4
  Connect the second RCA cable to the "ALC" jack on the rear panel of the amplifier. Connect the other end to the "ALC" jack on the interface buffer.
- 5
  Connect the red wire from the interface buffer to the positive terminal of the station's 12 volt DC power supply, and connect the black wire to the negative terminal. Plug the amplifier into a 115-volt electrical outlet.

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