[Boatanchors] FS: MULTI-ELMAC AF67 Transmitter AM-CW
Bry Carling
bcarling at cfl.rr.com
Sat Feb 16 13:37:24 EST 2013
FOR SALE: Multi-Elmac 60 Watts AM-CW, TUBE TRANSMITTER, Model
AF67.
THE MULTI-ELMAC AF-67 Trans-Citer is a ten-tube variable
frequency or crystal controlled seven band transmitter or
exciter. It uses a really good "push-pull" plate modulation
scheme with two 5881 modulator tubes.
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. The AF-67 Trans-citer employs a
variable frequency oscillator with output on wither 1.75 to
2.0 Mc. or 3.5 to 4.0 Mc. In addition to the V.F.O. feature,
two crystal positions are included for operation on two spot
frequencies. Any crystal that will work straight through,
double of 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
Trans-citer 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
scale is directly calibrated in megacycles for each of the
amateur bands. The AF-67 Trans-citer is supplied complete with
all tubes, viz: 6AK6 Oscillator, 6BJ6 Reactance Modulator,
6AG5 Buffer-multiplier, 6AQ5 RF Driver, 6146 Final RF
Amplifier, 6AU6 Speech amplifier, 12AU7 AF Driver, Two 5881 PP
Modulators, OB2 Voltage regulator
The AF-67 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 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.
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.
Dimensions: 11 1/4 inches wide, 7 inches high, and 8 1/2
inches deep.
Weight: 18 pounds.
There are some good articles on maintaining and modifying the
AF67 at some web sites. This one is unmodified as far as I
know. Fairly good condition for its age, and is complete, with
all original knobs etc.
One of these sold recently on eBay for $181.00
Will sell for only $99.00 plus shipping. Or next stop eBay.
Picture and details at:
http://af4k.com/radios.htm#AF67
73 - Bry, AF4K
More information about the Boatanchors
mailing list