Production Year 1965
The Drake T-4X is a SSB/CW and AM transmitter that covers the 80 through 15 meter amateur bands completely and 28.5 to 29.0 Mc of 10 meters. There are four extra crystal sockets which can provide coverage of additional 500 kc ranges between 1.8 and 30 mc when the appropriate crystal is installed(except between 2.3 to 3 mc, 5 to 6 mc and 10.5 to 12 mc).
The input power is 200 watts PEP for SSB/CW and AM. The output impedance is 52 Ohms and adjustable with the pi network. As with most transmitters built for the amateur market and including this one, the SWR should be 2:1 or less. The AGC circuit operates on SSB to prevent flat topping due to overdrive. This transmitter requires a microphone with a high impedance.
The tubes and their functions are as follows, a 12BA6 as the IF amplifier, 12BY7 as the Driver, two 6JB6 as the Power amplifier, 12AX7 as a Microphone amplifier and Sidetone oscillator, 6EV7 as the VOX amplifier, 6HS6 as the Premixer, 6AU6 as the AM modulator, 12AX7 as the AGC amplifier and Carrier oscillator and a OA2 for Voltage regulation.
Due to the 200 watt P.E.P. input rating, the T-4X will require a power supply capable of low voltage at high current with very good dynamic regulation. The voltage and current requirements are as follows: 650 volts at 200 ma average and 330 ma maximum with 10% regulation from 66 ma to 330 ma having a maximum ripple of less than 1%. 250 volts at 120 ma with 10% regulation from 82 ma to 120 ma. This includes the effect of the 650 volt supply change, if both voltages are obtained from the same transformer. Maximum ripple must be less than 1/4 %. Also needed is a -45 to -65 VDC adjustable filtered bias into 33 KOhm load and 12.6 Volt AC or DC at 3 amps.
The dimensions of this transmitter is 5 1/2" high by 10 3/4‘ wide by 12 1/4" deep and it weighs in at 14 pounds.
When the T-4X is matched with the R-4B it is capable of transceiver operation.