Production Year 1947 - 1953 at $49.50
This Hallicrafters S-38B is the third version of the S-38 family that was originally released in 1946. The Hallicrafters S-38 line included the models S-38, S-38A, S-38B, S-38C, S-38D, S-38E, S38EB and S-38EM. There are two versions of the S-38 without a letter suffix that is known to exist. The original S-38 had 6 tubes, a metal bottom cover and a smooth black finish on the cabinet. The second version of the S-38 which started production just prior to the model S-38A, had only five tubes, a cardboard bottom cover and a black wrinkle finish on the cabinet. All of the later models were essentially the same as the S-38A with the difference being the color and finish on the case and dials, some back panel changes and the way the power cord was attached. Although the C model used a 12SG7 tube rather then a 12SK7 tube as the IF amplifier. The A model had a smooth black finish, the B model had a black wrinkle finish, the C model had a Hammartone gray finish, the D model had a smooth gray finish, the E model was a smooth gray, the EB model had a beige finish while the EM model was a mahogany color. Beginning with the S-38D Hallicrafters radically changed the look of the receiver. It no longer had the half moon shaped dials, but rather a large rectangle frequency display very much like the Hallicrafters 5R10A. Starting with the E models, Hallicrafters added a BFO injection control on the rear apron of the chassis and changed the tube line up a bit. The Hallicrafters S-38 series of receivers remained in production from 1946 until 1961, an unheard of time span by the standards of today.
The Hallicrafters S-38B is a Superheterodyne, general coverage receiver that is used for the reception of AM and CW signals. The S-38B receiver incorporates 5 tubes in its circuit and has 4 bands with continuous coverage from 550 KHz to 31 MHz. The first band covers 550 KC to 1650 KC, the second band covers from 1.7 MHz to 5.1 MHz, the third band covers from 5 MHz to 14.5 MHz, and the fourth band covers from 13 MHz all the way up to 31 MHz. The Intermediate Frequency(IF) of this receiver is the standard 455 KHz. The internal roof mounted speaker is of the permanent magnet moving coil design that measures five inches across and has a voice coil impedance of 3.2 ohms. Received signals exit through a perforated section on the top of the unit. If headphones are to be used, the receiver requires a set with 500 to 2000 ohm impedance. This radio uses the standard #47 bulb for the dial lamp.
The Hallicrafters S-38B also features band spread tuning. The band spread dial is located to the right of the larger main tuning dial and is 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 lower 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 zero.
The photograph above on the left is of the front of the radio. Scanning across the front panel from left to right, the operator controls and their functions are as follows: at the top left is the Main Tuning knob, at the bottom left we run into the first of three front panel switches. This first switch is used to select the desired receiving mode and is labeled A.M. on the top and C.W. on the bottom. The next switch that we come to allows the operator to select between the internal Speaker or the use of Headphones. In the center of the receiver is the four position Band Selector knob that is used to select one of the four bands for reception. Next we run into the On/Off and Volume control knob. From here we move upwards and find the Bandspread knob. At the bottom right hand corner we have the last of the three switches which is labeled Receive on the top and Send on the bottom. The Send/Receive switch removes the plate voltage from the tubes of the S-38B which makes the receiver inoperative during times of transmission. This switch can also be used to conserve power during a stand-by 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.
The 5 tubes that are used in this receiver along with their functions are as follows: 12SA7 = Converter, 12SK7 = IF Amplifier & BFO, 12SQ7 = Detector and Audio Amplifier, 50L6GT = Audio Output, and a 35Z5 employed as a Rectifier. The power source requirements are 105 to 125 volts DC or between the same voltage range but with 60 cycles AC. The normal power consumption of the receiver is 30 watts. 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 87D1566.
The photograph above on the right is of the back of the radio. The connections and such found here are as follows, from left to right, 3 terminal antenna connections, serial number, headphone connectors, and at the right is the power cord. The text that is printed on the right side edge of the back panel directly above the power cord reads as follows, "CAUTION This interlock plug is provided as protection against dangerous electrical shock. Do not tamper with the interlock or attempt to operate receiver with the back off. The chassis of this appliance is connected to one side of the line.". In short, with the back panel removed it also removed the danger from electrical shock due to the power cord being disconnected. The model S38A does not appear to have this safety design. According to the 1953 book "Television and Radio repairing" by John Markus servicemen would use what is called a "cheater cord" to operate the set when such a safety device was built into its design. This cheater cord allowed the serviceman to operate the set with the back cover removed.
The 3 terminal antenna strip on the back panel is marked "A1", "A2" and "G" and known as Antenna 1, Antenna 2 and Ground. A jumper bar consisting of a strand of wire is normally connected between terminals "A2" and "G" for single wire antenna systems as well as unbalanced antenna transmissions lines. For a doublet antenna system with a balanced transmission line, the jumper between "A2" and "G" would be disconnected and the transmission line from the antenna would be connected to terminals A1 and A2. If a concentric transmission line(coaxial cable) with a grounded outer conductor is used, connect the inner conductor to terminal "A1" and the outer conductor to "A2" followed by a jumper wire between terminals "A2" and "G". The station ground connection is to be connected to the "G" terminal.