CW Transmitters

(Models DX 250, DX 250HDV, DX 350 and DX 350HDV)

These transmitters are designed for mobile or base CW operation. Powered by the 12 volt vehicle battery or 12 volt regulated power supply, the maximum power output is less than 5 watts RMS. Frequency of operation is within the 10 meter band, determined by installation of a crystal into the oscillator board. The transmitters contain a transmit/receive relay and an output connector for the receiver to share the antenna and permit break-in operation.

OPERATION:

  • Red "POWER" Button turns the unit on and off.
  • White "REC AMP" Button turns the receive amplifier on to provide 6dB of gain for your receiver. This will work independently of the power button -- that is, the white button may be pressed "on" even when the red button is "off." The oscillator may be operated without any output to the antenna. You will be able to hear the signal in your receiver. This may be useful to adjust your electronic keyer or to practice your Morse Code "off the air."
  • Green Button reduces power as follows:
    • "DIAL-A-WATT" switches the power output potentiometer into the circuit on models that feature variable power.
    • "SELECT-A-WATT" switches the output to low power on models without a variable control.
  • Yellow "DELAY" Button reduces power and adds delay to the transmit/receive relay to accommodate different transmission rates for break-in keying operation. (A Delay Rocker Switch is located on the back of those models that have only three push buttons on the front.)
  • Meter is an RF Relative Output Indicator and lights during transmission.
  • A Crystal made for series operation must be installed into the holes labeled "X-1" near the top of the oscillator board. The frequency should fall between 28.0 MHz and 29.7 MHz.
  • Key Jack for 1/8" miniature phone plug is located on the rear of the unit for connection of the telegraph key.
  • Power Cables are also located at the rear. The yellow lead connects to the positive side of the power supply, and the black lead connects to the negative side.
  • Antenna Connector (SO239) for 50 ohm antenna is located on the rear.
  • Radio Connector (SO239) for 50 ohm output to the receiver is also located on the rear. 

(Model DX 350HDV schematic - 281K)

 

Other Models 
SPECIFICATIONS:

Frequency Range

28.0 MHz to 29.7 MHz

Stability

50 parts per million, 0-50 degrees Celsius with typical quartz crystal

Power Output

< 5 watts

Voltage

13.6 volts DC

Amps

< 4

Impedance

50 ohms

Duty Cycle

100% at full output

Harmonics

> 30dB down

Dimensions

3-1/4"(H) x 5-1/4"(W) x 8"(D)

Weight

3-1/2 pounds