Note
QST, Feb 1960, p. 153.
Allied Radio catalog 1961 (copyright 1960), p. 396.
"Trans-Citer"
The Multi-Elmac AF-68 Trans-citer is a 9 tube variable frequency or crystal controlled six band transmitter or exciter. All circuits are simultaneously switched to the desired band by a single bandswitch control.
Designed as a complete transmitter for mobile or fixed installations, or an exciter to drive a higher power transmitter. When used as an exciter the 500 ohm tap on modulation transformer can be used to drive the higher power modulator.
The AF-68 was ideally suited for novice operation, though the $200 price tag may have been a little steep for the average novice. With the two crystal positions, crystal controlled operation is afforded and the power capabilities are within the legal limits required by novice regulations. Provision for CW keying is included.
With the inclusion of the 6 meter band, a highly stable VFO and full carrier amplitude modulation, the AF-68 was ideally suited for the Technician.
The AF-68 Trans-citer employs a variable frequency oscillator with output on either 3.5 to 4 MHz, 7 to 7.5 MHz, or 12.5 to 13.5 MHz. In addition to the VFO feature, two crystal positions are included for operation on two spot frequencies. Any crystal that will work straight through, double, triple or quadruple to the desired frequency may be used. The oscillator circuit employs a voltage regulator tube to maintain the plate voltage at a constant level.
The multiplier stages are broad tuned with a front panel control for peaking the final grid, insuring best performance on all bands. The audio circuit is designed to use either a carbon microphone or a low output microphone such as a crystal or dynamic. A slide switch on the transmitter sets up the circuit for use with either type of microphone. The variable frequency oscillator dial and the meter scale is illuminated. The variable frequency oscillator dial scale is directly calibrated in megacycles for each of the amateur bands.
The AF-68 is designed for use with a resonant antenna coupled to its output with a transmission line of 50 to 300 ohms impedance. Other impedance or balanced lines can be coupled through the use of an antenna tuning device. When used as an exciter the coupling link of the high powered final can be directly connected to the AF-68 with a suitable length of coaxial cable. The transmitter is designed for a maximum plate power input of 60 watts. Maximum ratings for the Trans-citer are 600 volts at 100 milliamperes; or 500 volts at 120 milliamperes. Full 100% modulation occurs when the modulator plate current swings to about 60% of the final plate current with normal voice frequencies.
Tube Lineup
– 6AK6: Oscillator
– 6AG5: Buffer-multiplier
– 6AQ5: R. F. Driver
– 6146: Final R. F. Amplifier
– 6AU6: Speech amplifier
– 12AU7: A. F. Driver
– (2) 6L6GB: Push-Pull Modulators
– 0B2: Voltage Regulator
