Hallicrafters Model S-120
This is a Hallicrafters S-120 4-tube communications receiver that tunes from
540 KC to 31 MC (540k HZ to 31 MHz) in 4 bands. The radio receives standard AM broadcast,
foreign and domestic shortwave broadcasts, radio amateur transmissions, ships, and
other stations. The receiver is a single conversion superheterodyne circuit - the intermediate frequency
is 455 kHz.
It receives both AM voice and CW (code) broadcasts with a built-in
fixed-frequency beat frequency oscillator (BFO). A switch on the front panel turns on
the BFO. The BFO control also acts as a sensitvity control making reception of extremely
weak signals possible.
It is designed to operate from 105 to 125 50/60-cycle (Hz) AC current or 210 to 250 VAC or VDC
using a special line cord adapter. The radio is an ac/dc set as it does not have a power transformer.
The radio has a selenium rectifier. Power consumption is 30 Watts.
An round permanent Alnico V magnet speaker is mounted on the right side of the chassis.
A 1/4-inch phone jack is provided on the front panel for plugging in a pair of headphones
with impedance from 50 to 10,000 ohms. Insertion of the headphone plug automatically disconnects
the internal speaker.
A Receive/Standby slide switch on the front panel permits silencing the receiver
without turning off the receiver.
The volume control turns the radio on and adjusts the volume.
The radio has a main tuning slide-rule dial and a bandspread side rule dial.
The Band 1 dial scale is the standard broadcast band. The standard broadcast band is marked with the old "CD" (Civil Defense)
emblem and a dot at 640 and 1240 kilocycles to indicate the former two official
civil defense frequencies. In a civil defense emergency, one would tune to either
of these two frequencies for official civil defense news, instructions, and information.
The shortwave bands are marked Band 2, 3, and 4.
The bandspread is at the top of the dial calibrated from 0 to 100. One sets the bandspread to 100 to make
the main dial calibrated. Turning the bandspread tunes the radio down in frequency.
The radio has a built-in ferrite antenna for AM broadcast and a 45-inch collapsible whip antenna
for shortwave reception. The whip antenna is often missing and must be attached to the external
antenna terminals when used. Provisions are included on the back panel for storing the antenna
when not in use.
The radio was manufactured between 1961 and 1964.
When I received this radio, it did work with some audio hum and it was in good cosmetic condition.
A previous owner had changed the selenium rectifier to a silicon diode and changed one of the power supply capacitors but left the original capacitor connected.
I replaced the other two capacitors and the emitter bypass capacitor of the audio output stage. I disconnected the wires to the original multi-section capacitor, but
left the original capacitor in the radio to preserve the original look. I realigned the oscillator and RF stages.
The radio works well.
Below is a picture of the bottom of the chassis. The two black and one blue capacitors are the three I replaced. The gray
capacitor is the one installed by a previous owner.
Below is a picture of the top of the chassis.
Below is another picture of the top of the chassis from the rear.
Below is a picture of the rear of the radio with the whip antenna installed on the antenna terminals.
Below is a picture of the radio with the whip antenna in its stowed position.
Below is a picture of the bottom of the radio.
||Det, AVC & 1st Audio
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