RCA-Westinghouse

Radiola Senior

The very popular, single tube receiver,  Aeriola Senior, was introduced in late 1921. By late 1922, it had been updated with a bakelite panel and mahogany box. Still later, in 1923, the name was changed to Radiola Senior.  These single tube, regenerative receivers perform quite well and are easy to operate requiring only a single 1.5vdc dry cell and a 22.5vdc B+ battery, a set of earphones and a suitable antenna and ground. The tube normally used is a WD-11, however an 864 or WE239A will work equally well but will require the use of a socket adapter. The working Radiola Senior shown is all original with the original booklet.

Federal Telephone and Telegraph Co.

DX Type-58

Federal  built high quality receivers though some of their circuits and mechanical devices seem rather "Rube Goldberg" at times. The DX Type-58, from late 1922, was designed for the enthusiast and the metal cabinet seems to show this. Selling price was somewhat expensive for a four tube set - $123. Federal's workmanship was excellent however their documentation is vague at best. It is interesting that Federal was so afraid of a RCA-Westinghouse law suit over the Regenerative Detector patent, they didn't tell owners (in their instruction manuals) that their radios could be set to regenerate and therefore significantly increase performance. Having "Regeneration" in print in an operator's manual would have been as good as an admission of guilt by Federal. Most owners figured out the adjustments anyway and the radios were fairly popular. By setting the "COUP" control to near "0" and advancing the "AMP" control to near the oscillation point, the DX Type-58 (and most other Federals) can be quite sensitive and selective receivers.

RCA-General Electric

Radiola V

In 1922 and 1923, GE couldn't supply enough radios to meet demand (60% of RCA sales.) Desperate to catch-up, they took their old shipboard receiver, the AR1300/AA1400, gave it a faux mahogany paint job, added a wooden top and base and created the Radiola V. The crystal detector is Perikon and can only be used as a crystal receiver alone. The three tube, regenerative receiver is a decent performer but selectivity suffers due to the single-circuit tuned input, which originally was designed for an RF amplifier to proceed it, as in the Radiola VI. The first models used 201As but later the Radiola V was offered with WD-12s.

Federal Telephone & Telegraph Co.

Type 61

Introduced in the fall of 1923, the Type 61 was Federal's high-end receiver, selling for an incredible $223. The circuit used six tubes - three RF amplifiers with grid-bias controlled amplification running into the detector stage and two transformer coupled audio amplifiers. One could select either one RF stage or three RF stages, a loop antenna input or external antenna input. One could also select various audio amplification circuits and the second audio interstage transformer has a selectable ratio secondary. In all, sixteen different configurations could be set-up, making the Federal 61 one of the most versatile battery receivers of its day. Though the manual is vague about the regenerative capabilities of the Type 61 ("regeneration" is never mentioned), performance can be excellent if the "COUPLING" is kept near minimum and the "RF AMPLIFICATION CONTROL" set near the oscillation point.

Atwater-Kent - Model 4560

Arthur Atwater-Kent made a fortune in the automotive ignition and lighting business but moved into radio parts manufacturing in the early twenties. By 1923, complete A-K radios were being offered. Shown is the 1924, Model 4560 (A-K 10-B) in standard finish, (black paint on the cans.) Original selling price was $100 and the TRF circuit provided good reception although the upper limit of the tuning was about 1200kc. Quality was top notch, as with all A-K receivers. There were many variations and different models of breadboard sets made between 1923 and 1925.

Crosley - Model XJ

Powel Crosley Jr. got into the radio business because his son wanted a crystal set. The prices were too expensive, in Crosley's opinion, so he bought a twenty-five cent booklet and built his first radio.  Noted for  good performance with inexpensive parts and cabinets, Crosley eventually became known as the "Henry Ford of Radio."  This is a 1924 Crosley XJ, a four tube TRF receiver.

Amrad - Neutrodyne

Amrad was one of the original members of the Independent Radio Manufacturers, a group of companies that were licensed to produce Hazeltine-Neutrodyne receivers. Amrad didn't offer their Neutrodyne receiver immediately, delaying introduction until the Christmas season of 1924. It was the last model Amrad produced before the company went bankrupt (June 1925) and was subsequently purchased by Powel Crosley. The Neutrodyne is a five tube set using an RF Amplifier, Detector and three Audio Amplifiers. The layout allowed for a verysmall cabinet with a low profile.

A.H. Grebe & Company

MU-1 "Synchrophase"

Arguably, the best performing TRF battery set made in the twenties. The circuit is a neutrodyne and Grebe was sued by Hazeltine (Independent Radio Manufacturers) because of it, though production of the MU-1 continued ultimately reaching over 150,000 radios. The MU-1 is very sensitive and will separate signals quite well due to its SLF condensers and binocular coils. Additionally, during its production many improvements were made, the most noteworthy is the bandswitch allowing further spreading out of the tuning. The bandswitch is actuated by the center dial at either end of its rotation. Chain-drive to the outer dials, driven from the center dial, was added early in production as an attempt at single dial tuning. Also, audio transformers and tube sockets were improved and the audio output tube changed (to a UX-112A) during production, which ran from late 1924 up to early 1927. The dial escutcheons were usually finished in lacquered gold but some later MU-1s had gold-plated escutcheons. The MU-2 is a dry-cell version using 199 tubes.

American Auto & Radio Mfg. Co.    -   American Beauty

Harry Schwartzberg was president of this small company located in Kansas City, Missouri. The American Beauty is typical of the 1925 to 1926 manufacturing style of TRF receivers built by companies that weren't members of the Independent Radio Manufacturers and therefore couldn't legally build neutrodynes. The circuit uses two standard TRF amplifiers, a Detector, two stages of RC coupled Audio Amplification and one stage of transformer coupled Audio Amplification - six tubes in all. The silk-screened panels became popular in the same time period and in many other models these panels became very elaborate works of art. The American Beauty artwork features a rose in each corner to honor its namesake.

HI-MU Radio Labs, Los Angeles  -   HI- MU

Many small Los Angeles companies were building and selling radios in the twenties. HI-MU Radio Labs is an unknown company that probably only built a handful of radios. "Built by William Ferringer" is engraved on the front panel but it is unknown what position Ferringer held at HI-MU (maybe he was the only "employee.") This particular HI-MU is serial number 91 but that figure cannot reliably be used as a reference for the quantity actually built. The circuit is unusual in that only four tubes are used in such a physically large radio. An RF Amplifier, a Regenerative Detector and two Audio Amplifiers. The AF Amps use ballast resistors to automatically control filament voltage while the meter can be switched to monitor RF Amp or Detector voltage. Remler tuning condensers are used along with Remler dials. Probably dates from around 1925.

Kemper Radio Laboratories

Model K-5-2

The Kemper K-5-2 Portable is a five tube TRF receiver with the AF output using a special 3-V Van Horne tube. 10 batteries are required for power and, when not in use, the loop antenna stows in the removable back cover, (there is also a removable front cover that is not shown.) Kemper Radio Laboratories of Los Angeles eventually became Kemper Radio Company.  This K-5-2 dates from about 1927. Performance is very good and sound quality is enhanced by the use of a built-in exponential horn. By the late twenties, most of the Los Angeles radio companies had to have their chassis built at Gilfillan Bros., Inc. due to the exclusive licensing arrangement that Gilfillan had with RCA.

Remloc Radio Co., San Francisco   -  Infradyne

The Infradyne circuit was designed by E.M. Sargent as a way to circumvent the RCA-Westinghouse held Superheterodyne patent and avoid an inevitable lawsuit. During the 1920s, no company could legally sell superhets other than RCA (their radios were built by "cross-licensed" companies, i.e. GE or Westinghouse) but kits could sometimes avoid legal problems. The Infradyne was originally sold only as a kit and by carefully avoiding the term "superheterodyne" in the manual, Sargent kept everything legal. The Infradyne circuit uses the sum of the incoming signal and the second harmonic of the local oscillator resulting in an IF frequency of 3500kc. Since the sum is used, the local oscillator frequency must be reduced as the incoming signal frequency is increased so the IF will remain at 3500kc. Also, the dial mechanism for the LO must work "backwards" if the dials are to seem to track together (have similar readouts.) All of these quirks kept the Infradyne kits safe from RCA lawyers. However, a few companies took their chances with legalities and sold completed kits, such as the Remloc Radio Co. version shown above. It differs from the standard Infradyne in that Thorola "Donut" coils are used in the front end, (Silver-Marshall coils were standard.) The Model 700 Infradyne (IF) Amplifier uses three UX-199s and is set to 3500kc. The LO is also a UX-199 but the remaining six tubes are UX-201A types. Performance on this working example is surprisingly good with low noise and ample sensitivity.

Beaver Laboratories

"Baby Grand"

Certainly one of the smallest radios built in the twenties, the Beaver Laboratories' Baby Grand is shown next to a quarter for size reference. This tiny crystal set dates from about 1922, or so. It is not certain if the Baby Grand was originally considered a "novelty" or a "real" crystal receiver.

Betta-tone Radio Co.

"Betta-tone"

These small crystal sets, built into a file-boxes, were popular in the mid-twenties. Construction was usually good and performance was satisfactory considering the low price they sold for. The Betta-tone is from about 1924. Like most of its contemporaries, the Betta-tone features a tapped coil with switched contact controls for tuning in stations and a "cat's whisker" to find a sensitive spot on the galena crystal for detecting the incoming signal. Earphones connect to the right binding posts while the aerial and ground connect the left binding posts.

Philmore Mfg. Co.

"Blackbird"

Philmore Mfg. Co. probably made more crystal sets, over a longer period of time, than any other manufacturer. Most of Philmore's line was fairly low quality with very low selling prices. The "Blackbird" uses a coil wound on a wooden form with a slider actuated by the tuning knob. The crystal detector has a glass cover over the "cat's whisker.". The black wrinkle finish metal case gives the appearance of a substantial amount of circuitry but the few componets used are all mounted on the back of the unfinished metal panel. This is an early Philmore from the twenties. Later Philmore crystal sets have molded plastic cases.

Uncle Al's Radio Shop

"Miracle" Crystal Set No. 2

Uncle Al's Radio Shop built the best performing crystal sets. Using multiple coils with fairly loose coupling with variable condensers for sharp tuning, the resulting selectivity is a "Miracle." Uncle Al's Radio Shop is still in business in Oakland, California, (though they now sell and service TVs.)  This Miracle Crystal Set No. 2 dates from about 1925. This working example of Uncle Al's design has received BC stations as far away as KNX in Los Angeles, California, (approximately 500 miles distance), quite a feat for a crystal set. Antenna was 75 feet long with earth ground, 'phones were Baldies (Baldwin Type C.)

CrystoFlex

It is doubtful that the CrystoFlex Company ever produced more than just a few radios. This model has all the indicators of a set assembled from purchased parts and then sold in the "neighborhood." Even the panel engraving was done by hand. The circuit uses two 201-A tubes with one tube reflexed as both RF and AF amplifier. The second tube is another AF amp and the detector is a galena crystal. Performance is adequate but tight coupling on the RF coils results in poor selectivity and the tuning range is narrow covering about 500kc up to 1000kc. The same circuit is shown in a 1923 LeFax Radio Handbook which would suggest that this model is from 1923-24.

Homemade Crystal Sets

Almost everyone has at one time or another built or used a "homemade" crystal set. They are easy to build, inexpensive and sometimes performance can be quite good. Through the twenties, crystal sets abounded with popularity and several examples can still be found. Popular materials used for the coil forms were Quaker Oats, Alber's Wheat or almost any round cardboard container that was available. Some high-class builders would opt for a pre-constructed oak box, such as the example shown, though most builders were content with just a wooden board to mount the parts on. The crystal set shown is from about 1922.

Atwater-Kent

Model 37 - "Modernistic Style"

The Model 37 was Atwater-Kent's first, self-contained, AC operated radio (the Model 36 had a separate, AC power pack.)  Rugged construction and the TRF circuitry resulted in a reliable, good performing radio. Although nearly all of the production was finished in a brown wrinkle finish called "Crystaline Enamel", sometime in the production year of 1928, a small number were finished in an "art deco" style. These Model 37s were dubbed "Modernistic Style" and featured a matching Type-E speaker. The silver and black decor is quite striking. This particular "Modernistic Style" was originally used in San Francisco's "Chinatown."