Production year 1961 - 1964 at $69.95 

The Hallicrafters S-120 is a single conversion, superheterodyne, general coverage receiver that is used for the reception of AM and CW signals. The S-120 turned out to be a very popular receiver for the Hallicrafters company and was the successor to their famous S-38 line. The receiver incorporates four tubes and a selenium rectifier in its circuit. The S-120 has a total of four bands with continuous coverage from 540 KHz to 31 MHz. The first band covers 540 KC to 1600 KC, the second band covers from 1.6 MHz to 4.4 MHz, the third band covers from 4.4 MHz to 11.5 MHz, and the fourth band covers from 10 MHz all the way up to 31 MHz. The analog slide-rule frequency display has been imprinted with a guide to the frequency settings for foreign, WWV, government, aviation, and other exotic stations.

The standard broadcast band has been marked in two places with a Civil Defense emblem which consists of a triangle inside of a circle. This CD emblem is found at 640 KHz and 1240 KHz. The operator was instructed to tune to one of these two frequencies for official news, instructions and information in the event of a civil defense emergency. The triangle emphasized the 3 step Civil Defense philosophy that was used before the foundation of FEMA and Comprehensive Emergency Management. When this receiver was manufactured, the Civil defense was an effort to prepare civilians for military attack. Civil defense uses the principles of emergency operations: prevention, mitigation, preparation, response, or emergency evacuation, and recovery. Programs of this sort were initially discussed at least as early as the 1920's but only became widespread after the threat of nuclear weapons was realized. Since the end of the Cold War, the focus of civil defense has largely shifted away from military attack to national and local emergencies and disasters. The new concept is described by a number of terms, each of which has its own specific shade of meaning, such as crisis management, emergency management, emergency preparedness, contingency planning, emergency services, and civil protection.  

The S-120 comes equipped with an internal speaker which is of the permanent magnet moving coil design that measures five inches across and has a voice coil impedance of 8 ohms. Received signals exit through a perforated section on the left side of the unit. If headphones are to be used, the receiver requires a set with an impedance of between 50 to 10,000 ohms. The S-120 employs a three-way antenna system for maximum flexibility. It has a built in ferrite rod antenna for the broadcast band, a 45 inch telescoping whip antenna, and connections located at the rear for an external antenna.

The Hallicrafters S-120 also features band spread tuning. The band spread dial has been calibrated from 0 to 100. To operate the band spread dial, set the main tuning dial to the high frequency limit of the range of frequencies to be covered and then tune stations in with the band spread control. For example: say that the 40 meter amateur band is to be covered. Set the main tuning dial pointer to 7.3 MHz and tune in the stations with the band spread control. The band spread control allows for fine tuning of stations and forces the operator to move across the frequency spectrum at a much slower pace, thus helping to insure that weak stations are not missed. Tuning the bandspread control from 0 to 100 tunes the receiver progressively higher in frequency. One thing to keep in mind is that the calibration of the main tuning dial will only be correct when the band spread dial is set to 100.

The operator controls of the S-120 consume the entire bottom portion of the front panel. Scanning across the front from left to right, the controls and their functions are as follows: Bandspread tuning control knob, On/Off and Volume control knob, a 1/4 Headphone jack which automatically disconnects the internal speaker when used. Located in the center of the S-120 is a control knob to turn On and Off the Beat Frequency Oscillator(BFO). The BFO is used primarily to provide the necessary beat frequency tone when receiving CW. In addition to this however, this control also acts as a sensitivity adjustment which aids in the reception of extremely weak signals. Next we run into the only switch that is found on the S-120. This switch is labeled Receive on the top and Standby on the bottom. This Receive/Standby switch removes the plate voltage from the tubes of the S-120 which makes the receiver inoperative during times of transmission. This switch can also be used to conserve power during a standby period when it would be important to have the radio spring to life with just a flick of a switch instead of having to wait for the tubes to warm up. Next is the four position Band Selector knob that is used to select one of the four bands for reception. The last knob on the right is the Main Tuning control knob.

The 4 tubes that are used in this receiver along with their functions are as follows: 12BE6 = Oscillator & Mixer, 12BA6 = IF Amplifier and BFO, 12AV6 = 1st Audio Amplifier, AVC and Detector, and a 50C5 as the Power Output Amplifier. The radio has two #47 dial lamps and is housed in a three sided sturdy metal cabinet. The Intermediate Frequency(IF) of this receiver is the standard 455 KHz. The power source requirements are 105 to 125 volts DC or between the same voltage range but with 60 cycles AC. It is also possible to operate the receiver from a 210 to 250 volt AC or DC power source by using a special line cord adapter with the Hallicrafters accessory part number of 087-201566. The normal power consumption of the S-120 is 30 watts. The physical dimensions of this receiver is 13 1/2 inches wide by 5 7/8 inches high by 8 3/4 inches deep and it weighs in at 10 1/4 pounds.

The photograph on the right is of the back of the Hallicrafters S-120. The back panel is not in place and is missing on this receiver. There is only two connections that are found on the rear apron as follows, at the left is a two terminal external antenna connection, and at the right is the power cord. The paper sticker to the left of the power cord lists the serial number of this receiver. The orange wire from the ferrite rod antenna does not make any electrical contact with the external antenna screw connection on the rear apron. I have added to the antenna terminal screw as a means to help hold the ferrite rod antenna in place since the back panel is missing.

The rear cover of the S-120 is labeled above the 2 terminal antenna strip with "GND" for the left terminal, and "ANT" on the right terminal. This is an abbreviation for "Ground" and "Antenna". The supplied 45 inch telescoping whip antenna should be connected to the "ANT" terminal. A ground wire should be connected between terminal "GND" and an earth ground for single wire antenna systems. A doublet antenna system with a balanced transmission line will have one side connected to terminal "ANT" and the other side of the transmission line connected to the "GND" terminal. If a concentric transmission line(coaxial cable) with a grounded outer conductor is to be used, connect the inner conductor to terminal "ANT" and the outer conductor to "GND". The station ground connection should be connected to the "GND" terminal.

The Hallicrafters models SW-500, WR-600 and WR-1000 are electrically the same radio but have a different color cabinet, dial bezel, and knobs.

The photograph on the left is of the left side of the Hallicrafters S-120 receiver. The internal five inch speaker rests directly behind the perforated section.

The picture on the right is of the bottom of the S-120. This photograph was taken shortly after the restoration work was nearly complete. In this picture some folks may notice the two strange looking bottom feet on the radio. They would be correct in their observation. When I first received this S-120, it was missing two of the bottom feet. At the time, I had no replacements so I made my own. I had some junk rubber straps laying around that I quickly cut to size and then put a recessed hole through so that I could attached them in place of the missing items.  

The photograph on the left is of the top of the Hallicrafters S-120 with the cabinet removed. This picture displays the tube compliment and some of the other major components that are found on the top of the chassis. The large yellow electrolytic capacitor has been left in place on the top of the chassis for aesthetic reasons. It is no longer being used in the circuit. 

The photograph on the right is of the bottom of the S-120 with the bottom cover removed. The audio transformer can be seen mounted onto the speaker at the left. The speaker in this receiver was in rough shape due to a couple of holes in it that a few bugs had chewed their way through. One was the size of a dime. What I did to fix these holes was to use some good ole Elmer's glue and tissue paper. I cut a piece of tissue paper(toilet paper, paper towel, etc. will work just as well) a little larger then the hole and then glued it to the speaker. I make sure that the tissue paper is completely covered with glue so that when it dries, it is solid with no fears of it riping. Also by covering the tissue paper with glue, it gives it roughly the same firmness as the original paper cone on the speaker. After this repair has been made, the speaker will be solid and there is no longer any worries that the holes and tears will become larger as the speaker oscillates. If the speaker has a tear in it, simply run a bead of glue down the tear and in most cases, it will stop the tear from getting any worse as well as restore the audio quality of the speaker. While some audiophiles may gawk at the idea, I can not tell any difference in the sound quality of this little receiver.

The little orange things are capacitors and are commonly referred to as "orange drop capacitors". It is often recommended to replace all of the molded paper and waxed paper capacitors in these older receivers which has been done for this restoration. The reason being is that over time the old capacitors may start to dry out and become open, shorted or leak which can hurt the performance of the receiver and possibly cause serious damage to some of the components.

Also notice on the left hand side that new electrolytic capacitors have been installed as well. They are the bluish/black colored cylinder shaped items underneath the green selenium rectifier. Some times when I do these restorations I will drill out the gunk from inside the old original capacitor and stuff the new replacements inside. I normally do this so that the radio will keep its original appearance. Capacitors that are made today are not only sturdier and more precise, but are also much smaller. A capacitor from yesteryear that was the size of a roll of quarters is now the size of a pencil eraser today. In most cases, the new replacement capacitors will easily fit inside the body of the old capacitor. Some folks have been known to take this a step further and go so far as as to even stuff both the waxed paper and molded paper capacitors to give the set a museum quality restoration. As an added touch I have installed heat shrink tubing over any of the bare wire near the positive side of the electrolytic capacitors. The heat shrink tubing can be thought of as carpenters caulk, it gives the work a nice and neat appearance. All of the electrolytic capacitors have the same ground connection point. Before I solder any wires or leads to the chassis or to the tube pins, I clean the oxidation and other gunk from the connection point with a Dremel tool using a wire brush attachment.    

During the restoration of this radio I found only one resistor that was out of tolerance. Even after replacing that resistor and doing a global replacement of all the capacitors(except the disc type) this receiver was very close to being on frequency when I ran through the alignment procedure. It simply needed just a gentle touch to be nearly right on the mark.

If the cabinet is ever removed from the chassis, the rubber grommets, fiber washers and nylon insulators should be inspected and replaced if they are damaged. Four of these white insulation grommets can be seen in the picture above that shows a view of underneath the chassis. The insulation grommets are located in each of the four corners of the chassis. Two more can be seen in the photograph of the back of the receiver at the top of this web page. These insulation grommets electrically separate the cabinet from the chassis. It is very important that the cabinet be insulated from the chassis. WARNING!! It is very important that you do not rely on these insulators a half a century later. A lot could go wrong such as, are they still in good condition, did a previous owner reassemble the radio properly, and so on. With these AC/DC sets, depending on which way the power cord is plugged into the wall can put the entire receiver at 120 volts above ground. This means that if the operator has one body part resting on an earth ground and reaches over and touches an exposed part of the receiver, the operator can receive a potentially fatal shock.

The partial schematic above is for the Hallicrafters S-22R receiver. This schematic would feel right at home with many of the AC/DC receivers, or numerous other electronic items that are built this way. There is no power supply transformer in the circuit of these items which makes them dangerous if the operator becomes careless. Actually, the reason the set can run from a DC power source is because there is no transformer. Today, an item built this way and with a metal cabinet would never get past the Underwriters Laboratory(UL). In fact, if you were to take a survey of the electrical items in your house, what you will most likely find is that just about every appliance with a metal case has a three prong power cord attached to it. As seen in the schematic above, the item will work no matter which way it is plugged into the wall. One way allows the chassis to be connected to the hot wire in the home wiring, while flipping the plug the other way connects the chassis to the neutral side of the house wiring. Either way can be dangerous as both the hot and the neutral house wires in the U.S. carry current. Even though at the fuse panel both the neutral and ground wires go to the same place.

Picture this, the receiver cabinet is hot with 120 volts of AC. You have a hand resting on a desk lamp that uses an older non-polarized power cord or is grounded by a newer 3 prong plug, or your hand is resting on the station ground, or your feet are propped up on the heater, or a thousand other possible ways you could easily be at ground potential, now you reach for a switch on this radio and ZAP, the current runs through your body as it makes its way to ground and kills you. Now your wife becomes a widow and we see your stuff listed at auction under the title "From the estate of a SK". I realize that this sounds harsh, but in most cases there are no second chances. What's that I hear you say? You fully understand the dangers and will watch out for this? What about a family member when you are not home? Do they also understand the danger? Do not risk it. Explain the dangers to them and check the voltage on the chassis with your VOM with the on/off switch in both positions. An isolation transformer can also be used, or better yet, unplug the device when you are away.

Resources:

Radios by Hallicrafters with Price Guide by Chuck Dachis

Hallicrafters owners manual

Sam's photofacts by Howard W. Sams & Co., Inc.