The MULTI-ELMAC AF-67 Trans-citer is a ten tube variable frequency or crystal controlled
seven band hansmitter or exciter. All circuits are simultaneously switched to the desired
band by a single bandswitch lever.
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 modulators.
1.2 DIMENSIONS.
The maximum external dimensions of the AF-67 Trans-citer, excluding projections of
control knobs, is 11-1/4 inches wide, 7 inches high, and 8-1/2 inches deep behind panel. Approximate
weight is 18 pounds.
1.3 CIRCUIT DESCRIPTION.
The AF-67 Trans-citer employs a variable frequency oscillator with output on
either 1.75 to 2.0 Mc. or 3.5 to 4.0 Mc. 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,
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 rear apron on the AF-67
Transciter sets up the circuit for use with either type of microphone. A reactance tube modulator
is incorporated in the variable frequency oscillator circuit for narrow-band-frequency-modulation.
The variable frequency oscillator dial and the meter scale are indirectly illuminated. The variable
frequency oscillator dial scale is directly calibrated in megacycles for each of the amateur bands.
1.4 TUBE COMPLEMENT.
The AF-67 Trans-citer is supplied complete with all tubes, tested in the individual unit, as follows:
6AK6
Oscillator
6BJ6
Reactance modulator
6AG5
Buffer-muliplier
6AQ5
RF. Driver
6146
Final RF. Amplifier
6AU6
Speech amplifier
12AU7
A.F. Driver
5881 (2)
P.P.Modulators
OB2
Voltage regulator
#44 (2)
Pilotbulbs
1.5 OUTPUT.
The AF-67 Trans-citer 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-67 with a suitable length of coaxial cable.
The MULTI-ELMAC AF-67 is designed for a maximum plate power input of 60 (sixty) watts.
Maximum ratings for this 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.
1.6 AUDIO.
The modulation transformer is provided with a 500 ohm output tap brought to the power
plug for driving the grids of high powered modulators. The 5881's will deliver approximately 40 watts
of audio with a plate supply of 500 volts.
1.7 POWER SUPPLY.
The AF-67 Trans-citer was intentionally designed to use an external power supply
in order to permit:
use of PMR6A receiver power supply to supply the low level stages,
use
of the AF-67 Transciter with an AC operated power supply at a fixed or portable location,
use
of a dynamoter or vibrator supply in mobile installations, or
use of the Trans-citer as a driver-exciter for high powered transmitters.
A suitable MULTI-ELMAC power supply MODEL PS-2V
for portable or fixed station operation from 115 volt AC lines is available.
1.8 POWER CONNECTOR.
A 15 prong female connector is provided with each unit. The 15 prong connector
allows all circuits to be arranged for maximum flexibility. Making if possible to use the AF-67
Trans-citer in various types of installations.
1.9 ACCESSORIES.
The following accessories are available for use with the AF-67 Trans-citer:
PS-2V
A universal 115 volt AC power supply. (Supplies 6 or 12 volts AC for filaments and
two separate high voltages.)
CFS-l
Cable with a 15 prong female connector and fanning strip to connect the AF67 to the
PS-2V power supply.
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