Radio Boulevard
Western Historic Radio Museum


WHRM Radio Photo Gallery


- Roaring 20s Radios -

Battery Sets, Crystal Sets and Early AC Sets

1920 to 1929




Photo right:   Let's face it. Radio wouldn't have been "RADIO" without these guys. Center is Guglielmo Marconi. Left is Owen Young, board chairman of RCA, on the right is Ed Nally Jr., president of RCA. Owen Young, originally from GE, was instrumental in forming RCA from GE radio assets and with the acquisition of American Marconi in 1919. Ed Nally Jr. was former vice president of American Marconi and became the new president of RCA (pres. from 1919 to 1923.) RCA was officially created in November, 1919. This photo was taken on board Marconi's yacht, the "Elettra."   photo: Radio Journal, Sept. 1922


Battery Sets  - 1922 to 1927


Westinghouse for RCA


Westinghouse cross-licensed with GE/RCA in 1920, offering the Superheterodyne patent and the Regenerative Detector patent as their end of the agreement. Commercial Radio Broadcasting was about to start with Westinghouse's KDKA radio station located in Pittsburgh, Pennsylvania going on the air in November 1920. The first radio offered to the public for listening to the new broadcasts from KDKA was some gear that Westinghouse had built for ham market (radio amateurs.) The hams were less than enthusiastic about the RA and DA sets as ham receivers. So, lucky for Westinghouse, here was a new market for these sets - the Broadcast Radio listeners. These neophyte-listeners weren't nearly as critical as the hams were and the RA and the DA sold quite well. By mid-1921, Westinghouse had combined the RA-DA into one cabinet and designated this model the RC. The RC was produced well into 1922. Westinghouse also offered an Antenna Tuner (RT) and an RF amplifier (AR) in matching boxes, that is, matching the RA-DA.

The circuit uses three 1A pure tungsten filament tubes, a UV-200 soft detector and two UV-201 hard amplifiers. Early versions of the DA used WR-21 or similar tubes since the UV-200 and UV-201 weren't available until late-1921. Regeneration is via a tap switch (Tickler.) Performance is dependent on how good the tubes are. Pure tungsten filament tubes can't be rejuvenated and when the tungsten is exhausted of its ability to emit electrons, the tubes no longer function (even though they will "light up.") With good emission tubes the RC will perform adequately but it isn't very selective. This is due to the single-circuit tuner used. The addition of the RT and the AR improve selectivity and over-all performance. However, this "component" approach, while popular with enthusiasts, didn't appeal to the regular Broadcast listeners.


Westinghouse for RCA

Radiola Grand - Model RG

The Radiola Grand was the deluxe radio receiver from RCA-Westinghouse for 1923. Designed to replace the unsuccessful Aeriola Grand (with its ballast tubes and strange circuit adjustments - one had to pull tubes to lower the volume!), the Model RG was a great performer and its gold-plated hardware gave it that impressive, expensive look. At $325.00 in 1923 - it WAS expensive! Using four WD-11s, the circuit is a regenerative detector with single AF driver and Push-Pull output. Interstage transformers are used for coupling. Sound quality is excellent (for a battery set) using the built-in horn speaker. Note on the grille cloth: Originally RGs did not have grille cloth, however this brocade cloth was probably installed by the first owner or perhaps the dealer. Also, two styles of grilles were produced. The type shown is the later version grille.

The cross-licensing agreement with Westinghouse and General Electric (along with Wireless Specialty Apparatus, AT & T and RCA) was going to have GE provided 60% of the radios that RCA could sell. Westinghouse and WSA provided the remaining 40%. However, it took awhile for GE to get up to speed and most of the 1921, 1922 and 1923 radios were actually from Westinghouse. GE only provided the Radiola V and a few other models that were actually old shipboard radios that GE converted to look like consumer radios. Although GE had created RCA with their own assets and with the purchase of American Marconi (Oct. 1919,) GE decided to keep the American Marconi plant in New Jersey for themselves rather than let RCA build their own radios. This kept RCA under GE control, along with help from Westinghouse, throughout the 1920s. RCA didn't build any of their own gear (except for Radiomarine Corp of America shipboard radios that were built at the WSA plant) throughout most of the 1920s. Things changed in the late-1920s with RCA acquiring many of their own patents and finally with their purchase of the Victor Talking Machine Company (purchased with the financial help of GE and Westinghouse in 1929.)

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Westinghouse for RCA

Radiola Senior Regenerative Receiver - Type RF

 Radiola A.C. 2 Stage Audio Amplifier - Type AC

The very popular, single tube receiver,  Aeriola Senior, was introduced in late 1921 for $65. 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 (price was still $65.) A two-stage AF amplifier was an accessory to the Aeriola Sr. and also to the later Radiola Sr., also priced at $65. The 2-Stage Audio Amplifier added enough audio gain that a horn speaker could be used on most of the stronger signals, thus allowing the entire family to enjoy "the radio." The Aeriola and Radiola 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 (WE-239A is shown installed in the Radiola Senior.) The AF Amplifier requires two WD-11 (or compatible substitutes) along with a set of dry cells for the filaments and a 60 to 90vdc B+ battery. The amplifier is shown with later type WD-11 tubes installed. The horn speaker was optional.


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.


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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.


A. H. Grebe & Company

Broadcast Receiver CR-12

Alfred Henry Grebe was one of the very early radio builders. He was a very young teenager when he was building radios for neighbors and, by 1917, at age 22, he had a contract to build WWI submarine receivers. Grebe produced various types of ham equipment shortly after WWI ended and the "radio ban" was lifted (September 1919.) His earliest radios built before the 1921 "radio broadcast boom" were communication receivers for hams and some commercial users. This was the beginning of the "CR series" of Grebe radios that, while some are strictly for communications (the CR-7, for example,) many could double as broadcast receivers (the CR-9.) In fact, some of the CR sets were intended only as broadcast receivers, the CR-12, for example (it's labeled "Broadcast Receiver" on the front panel.)

Grebe always believed that the mechanical construction of a radio was just as important as the circuit design. Much of Grebe's advertising stressed this belief. Even the argument used in the Hazeltine lawsuit over the Grebe Synchrophase unlicensed use of the Neutrodyne circuit was that the mechanical design and construction gave the Synchrophase its incredible performance, not the Neutrodyne circuit (more details on the lawsuit in the Grebe Synchrophase section further down this page.) All of the CR series are well-built receivers but the circuits are not unique to Grebe. After all, he did have a 1914 Armstrong license to build regenerative detector receivers. That didn't stop Westinghouse from suing Grebe after they had purchased Armstrong's patent in 1920. At the time, Grebe stopped sending the payments to Armstrong and just sent the regenerative license payments to Westinghouse instead (and they just kept on cashing the checks.) Ultimately, that's what lost the case for Westinghouse. Grebe had paid the license fees and Westinghouse cashed the checks therefore Westinghouse must have agreed to the terms of the license deal. At any rate, Grebe continued to build regenerative receivers up into the later twenties, although most of these were for ham radio use.

The CR-12 is from 1923 and it uses four tubes. UV-199 tubes installed into regular bayonet-sockets using socket adapters was the intended tube lineup although 201-A tubes could also be used by removing the adapters. Small pull-switches next to the filament adjustments marked C1, C2, C3 and C4 provide the additional filament resistance for each tube when UV-199s are used. Tuning is accomplished using variometers rather than air variable capacitors. The secondary tuning is calibrated in meters along with the 0-100 scaling. Regeneration is accomplished by increasing the RF amplifier tube signal-grid input through varying the resistance of the variometer stator to B-/Ground. Additionally, the level of RF amplifier filament voltage will also affect the RF gain and the tendency towards oscillation. These two controls are adjusted until the RF stage breaks into oscillation, then the Regeneration control is reduced until the oscillation stops. This high-gain RF signal is routed through the coupling coil to the Detector tube variometer.   >>>

>>>   The combining of both tuned-regenerative RF amplification plus tuned input Detector gives the CR-12 excellent sensitivity and adequate selectivity for broadcast reception. Since the CR-12 was intended as a "Broadcast Receiver" regenerative oscillation was a condition to be avoided. The proper setting for AM demodulation would have been just before the RF stage breaks into oscillation. The audio amplifier stages are standard transformer coupled circuits. The cabinet is much deeper than other Grebe CR receivers to allow two storage compartments for dry-cell batteries when using UV-199 tubes. 201-A tube filaments would require using a storage battery that had to be located outside the radio cabinet (holes for the external A battery cables were provided.) The B batteries would still occupy the other storage area. C bias is not used in the CR-12. The cabinet is constructed of solid walnut finished in lacquer. The panel is the standard Grebe CR finish which is grained bakelite giving it a flat black appearance. The CR-12 sold for $175 in June 1923.

 MODEL 4560 - a.k.a. 10-B, "A-K Breadboard"

Arthur Atwater-Kent made a fortune in the automotive ignition and lighting business but moved into radio parts manufacturing around 1922. Initially, A-K offered various kinds of radio parts to build your own receiver. By 1923, complete A-K radios were being offered. A-K believed his manufactured parts were beautiful (and so do a lot of collectors) so exposing them on open boards seemed the logical design for his receivers. Initially, small receivers were offered but the radio market was "hot" so A-K enlarged the receivers up to five tubes using a standard TRF design. The first Model 10 was called a "Radiodyne" but within a couple of weeks, Western Coil informed A-K that they owned the Radiodyne name. A-K immediately stopped any use of the name Radiodyne on his receivers. There were several Radiodyne A-K breadboards sold so they do show up from time to time. The first Model 10 breadboards have terminals for connecting power but later sets used a battery cable.

Early Model 10s also have the RF coils mounted in the same axis but later this was changed to prevent coupling between stages. Most of the Model 10 breadboards were sold during the 1924 year. The last Model 10, the 10C, was a reduced size board with the components mounted much closer together. The 10C was sold in early 1925. Original selling price for the A-K breadboards was usually around $100. 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. Most models had both standard, or black wrinkle finish paint, or deluxe, brown wrinkle finish available. There are many variations and different models of breadboard sets that were made between 1923 and 1925. Shown in the photo above-left is the 1924, Model 4560 (A-K 10-B) in standard finish, (black paint on the cans.) I've owned this AK-10B since the late-1980s. It does work.

Harold E. Greenwood's A-K 10B

Anyone who has been collecting antique radios for awhile has probably heard of Harold E. Greenwood. He is best known for his book "A Pictorial Album of Wireless and Radio 1905-1928" published by Floyd Clymer in Los Angeles, California in the early 1960s.

Greenwood was a radio collector who took the time to research and photograph much of his collection and other collections to compile his book. About a decade later, Morgan McMahon published the book "Vintage Radio" which was based on Greenwood's original album. Vintage Radio came out in the early seventies and had almost everything in it that had been in Greenwood's book. McMahon also published a list of radio descriptions that had been complied by Greenwood. The manufacturers were listed along with all of the known models and included number of tubes, circuit, number of tuning dials, original selling price and more. This book was called "The Collector's Guide to Antique Radio" and it was also available in the mid-seventies. McMahon then came out with "Flick of the Switch" that chronicled radios from the 1930s up to the 1950s. FOTS also covered vintage ham gear and had a write up on radio repair. These were great books that really helped antique radio collectors that were interested in manufacturing history and circuit types,...they weren't price guides. Shown in the photo above-right is an A-K 10B that was once owned by Harold Greenwood W6MEA and also by Morgan McMahon "Vintage Radio" (name labels were installed on the underside of the breadboard.) Photo left shows the cover of Greenwood's book.


Shown in the photo to the right is one of Atwater-Kent's component parts that were being sold in 1922 and 1923. This is a two-stage, transformer coupled audio amplifier. Connections are via binding posts behind the tube sockets. The potentiometer adjusts the filament voltage on both tubes as a method to control gain or output level. Although the intended tubes were probably UV-201A tubes, this TA was found with two good condition WD-12 tubes installed. Early A-K cans were painted an olive-green color and some of the very early breadboard sets also have cans with this color paint applied. All of the later cans are either black or brown wrinkle finish paint.



 Type 4-C

Rudolph Wurlitzer's main business was musical instruments but, like many other businesses in the early twenties, he wanted to get involved in radio. Officially, the Wurlitzer connection to All American Mohawk seems to have originated earlier when Wurlitzer made cabinets for Mohawk Corporation. At that time All American Radio Corporation was one company and Mohawk Corporation was another. All American was started by E. N. Rauland and specialized in transformers and wire. By 1922, the company had become All American Radio Corporation. Mohawk started as Mohawk Electric but soon was just Mohawk Corporation. Mohawk had Wurlitzer building cabinets for their radios and Wurlitzer had radios shown in the catalogs that were probably made by Mohawk. By early 1928, All American and Mohawk combined to become All American Mohawk. Wurlitzer continued to supply cabinets and still offered radios for sale that were built by All American Mohawk. Later, these radios were tagged as "Lyric" brand. Eventually, All American Mohawk went bankrupt and Wurlitzer, frustrated at really never making any money in radio, got out of radio all together in 1937.

The Type 4-C was probably built by Mohawk Corporation. The 4-C was probably sold in Wurlitzer stores. Its styling looks like 1923-4. The 4-C uses four 99 dry cell tubes and the circuit is TRF with a regenerative feedback (Volume) and variable coupling (Selector) but those controls are labeled with more generic terms to avoid patent infringement problems. Low-loss "spider web" coils are used. The 4-C features ample battery storage within the cabinet but behind the left door is the built-in horn speaker.


General Electric for RCA

AR-812  Second Harmonic Superheterodyne

The AR-812 was the first production superheterodyne offered to the general public. Western Electric was producing commercial superheterodynes earlier and supposedly installed one in the White House. That "fired up" David Sarnoff, who was RCA's GM at the time, to have GE build a superhet for RCA to sell. As with many new types of circuits, the AR-812 prototypes didn't work very well with internally generated noise due to reflexing some of the circuits. Ed Armstrong was called in as a consultant and the problems were reduced to the point where the receiver could be offered for sale. RCA was aiming for Christmas 1923 but delays moved the release date to February 1924. The incredibly high selling price of $235 didn't seem to deter the radio enthusiasts and the AR-812 sold very well. It sold even better when the price was reduced and, by 1925, new-in-the-box, surplus production left-overs, were being sold for $10. The AR-812 did out-perform most of the competition and with a large indoor loop antenna, coast-to-coast reception was possible. Six UV-199 tubes are used and the receiver does have have a small built-in antenna. In fact, some of the advertising for the AR-812 promoted the receiver as being "portable."

The AR-812 uses what RCA called "catacomb" construction. Most of the receiver circuitry and components were contained in a metal box that is filled with hard wax. The external flexible wire connections were called "whiskers" for some reason. It is possible to determine faults in a catacomb by measuring the resistance between various whiskers. RCA provided the data and procedure for testing catacombs. However, RCA wanted the defective catacombs returned or exchanged for good ones when doing repairs. Not possible today, of course, and most restorers repair their own catacombs (if they want the receiver to function.) I use a second-hand toaster oven (usually a few dollars at thrift stores) set to 180F or so to melt out the wax. It will be necessary to carefully remove the lead seals to preserve the embossed "RCA" on them. Also, sometimes a vent hole has to be drilled to allow the heated wax to flow out. Once the wax is removed, repair is straight forward. You'll almost certainly find that some of the very fine wires used in the circuit have broken. This is probably due to expansion and cracking of the wax breaking the fine wires. Once the catacomb is repaired, you don't need to refill it with wax again. RCA used the wax as a method of keeping the superheterodyne construction secret or at least from becoming common knowledge to the technoids of the time.

The AR-812 shown in the photo was found (in 1993) in the upstairs storage rooms above the Crystal Bar in Virginia City, Nevada. The Kolster Loop Antenna (Federal Telegraph Company) and the RCA UZ-1325 horn-speaker were with the AR-812 and the radio had all six 1.5vdc dry cells still installed. The "station cards" are vintage and were penciled in with west coast stations. In the past, the radio had been operated using dry cells for the filaments and an AC operated "B eliminator" for the higher voltages. Just how long the radio, loop and horn had been upstairs is hard to say. Bill Marks, who owned the Crystal Bar then, was an avid collector of all kinds of antiques. The Crystal Bar was famous for its display of various kinds of orchestrons, nickelodeons and other types of mechanical music players. The upstairs was filled with other types of antiques including phonographs, radios and parts. Everything was eventually sold off when Marks died. The Crystal Bar is now the Visitor's Center for Virginia City operated by the VCCTA.

AR-812 with UZ-1325 Horn and Kolster Loop


Crosley Radio Corp.

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 instead and built his first radio. Realizing how easy it would be to build and sell simple receivers, Crosley bought Precision Electric (in 1922) to begin his radio business and the following year formed Crosley Radio Corporation from Precision Electric. Crosley radios are noted for  good performance with inexpensive parts and cabinets. By keeping manufacturing costs low, Crosley was able to offer his radios at very low prices resulting in high sales. His methods of manufacture eventually led to his becoming known as the "Henry Ford of Radio." Crosley went on to owning BC station WLW, owning the Cincinnati Red Legs baseball team, building small cars and many other endeavors. Shown is a 1924 Crosley XJ, a four tube TRF receiver.


Crosley Radio Corp.

Model 51

One of the most common Crosley battery operated regenerative receivers is the Model 51. Crosley sold them for $25 and the little two-tube radio performed quite well. Certainly, the Model 51 shows what can be accomplished when the goal is to build a two-tuber (regenerative detector and one stage of AF amplification) as economically as possible. Crosley was already famous for their ultra-simple "book condenser" that replaced the expensive tuning condenser. The "tickler" was a push-in or pull-out type of control that allowed the operator to control regeneration by changing the proximity of the tickler coil to the secondary coil. A simple push or pull of the regeneration knob changed the position of the tickler coil behind the panel to adjust the regenerative feedback. Most of the other parts used in construction are standard for the period. The cabinet is made out of poplar wood and was given a very basic finish (probably just a coat of shellac.) It didn't matter how cheaply made the Model 51 was - it performed quite well, better than many other more expensive sets. Crosley sold thousands of the Model 51 for that very reason. The Model 51 was available from 1924 through early-1925. The Model 51 shown still has its complete original warranty card attached under the lid. The date on the card is interesting, Dec.25, 1924 - Christmas Day. This 51 is in "as found" condition.


Gilfillan Bros., Inc.


The Gilfillan Brothers were Jay and Sennett Gilfillan. They started a smelting business in Los Angeles, California around 1913. A bakelite molding process was added to the business and by the early twenties, the Gilfillan Bros., Inc. was producing bakelite molded electrical and radio parts. Knobs, variometers, variocouplers and other types of  parts that required molded bakelite parts to construct radios. To complete in radio, Gilfillan bought a controlling interest in a small radio company that had a Neutrodyne license. By 1924, The GN-1 Neutrodyne was being offered. From the bakelite molding and smelting business, in addition to their radio business, the brothers opened plants and sales offices in New York City and Kansas City. By the mid-twenties, Gilfillan Bros.,Inc. had the attention of the Radio Group who started to put pressure on the company. This ended up with Sennett Gilfillan traveling to New York City to confront the RCA officials. General Manager, David Sarnoff met with Gilfillan and offered exclusive RCA licenses for all eleven Western states if Gilfillan would close all offices and plants not in those states. Gilfillan accepted the deal and by the end of 1928 all legally licensed radio manufacturing in the West had to go thru Gilfillan. By 1931, the superheterodyne was added to Gilfillan's exclusive licensing. This arrangement with RCA allowed small radio companies to build their radios at the Gilfillan plant which gave the small companies licenses as Gilfillan's sub-contractors. This method of building radios in the West continued all thru the thirties.

The GN-3 was a small dry-cell radio set that used four tubes. The circuit was a Neutrodyne with one TRF stage, detector and two stages of audio amplification. UV-199 tubes were used. Dates from mid-1925 and sold for $65.


R. E. Thompson Mfg. Co.

The Thompson Grandette - V-50

Roy E. Thompson worked in the Department of Commerce, then for Kilbourne & Clark before buying Wireless Improvement Company around 1917. He started R. E. Thompson Mfg. Co. to obtain a Neutrodyne license from the Independent Radio Manufacturers. The "Independent Radio Manufacturers" was formed by eleven companies who wanted to develop a radio that could compete with the GE-RCA-Westinghouse owned Superheterodynes. They approached Louis Hazeltine for the design work and the Neutrodyne was born. It used capacitive feedback in the RF amplifiers to cancel the tube's interelectrode capacitance which then allowed for higher gain in that stage without oscillation instability. The RF coils were physically oriented at 45 degree angles (tilting) or a 90 degree mounting relationship to reduce any stray coupling between RF stages. The Neutrodyne, when properly designed and manufactured was the best performing TRF radio receiver of the time. While it didn't always perform as well as a Superheterodyne, it certainly performed better than any other type of TRF receiver. Unfortunately for all other manufacturers, unless you were an original "Independent Radio Manufacturer", you couldn't legally build Neutrodynes (see "Grebe MU-1" below.)

The Thompson V-50 was introduced in October 1924. It is a well-built Neutrodyne using five tubes that consisted of two Neutrodyne RF amplifiers, Detector and two stages of audio amplification. Interestingly, the V-50 allows the option of either using the C- bias or not, all controlled by connecting or disconnecting a metal strap across the bias battery connection terminals. At the time, the only reason for using C- bias in the audio section was to prolong the life of the B+ batteries. Also, a "dummy plug" is installed in one of two chassis jacks marked "1" or "2" to select whether one or two audio stages are used for the output jack on the front panel. The Grandette V-50 styling is typical of the 1923-24 Neutrodynes, that is, black panels and three symmetrically mounted tuning dials. Inside the workmanship is first-class. Thompson also sold a matching horn speaker that featured a direct-driven conical diaphragm.

Thompson radios were high priced with the V-50 selling for $125 in 1924. Thompson radios looked like the typical Neutrodyne (e.g., the early FADA.) A few other manufacturers had models out there at half the cost of Thompson's least expensive models. Those cheap radios weren't Neutrodynes but most radio consumers didn't know the difference and were only concerned with the price of their intended purchase. Take a look at the early Freshman Masterpiece (which actually came out before the V-50) as an example of a radio that looked convincingly like the typical Neutrodyne but sold for only $60 (Freshman write-up below.)   >>>

>>>   To the radio-buying public, the Freshman was the better deal - until they got it home and found out how badly it performed. The Thompson V-50 would easily "bury" the Freshman in all areas of performance. Unfortunately, the new Freshman owners found out too late that they had been "taken" by Charlie Freshman.

Thompson's sales were never as high as expected and the company was in constant debt, despite introducing new models. By the end of 1927, Thompson was out of business. Interestingly, Charlie Freshman was also about to be forced out of his company. The days of selling "really cheap" radios were about to end with the introduction of lightsocket-powered radios - AC-operated in most areas, DC-operated in Edison-powered areas (rural areas still had to stick with battery operation.) Even a merger with Freed-Eisemann didn't help Freshman since the 1929 Stock Market Crash was right around the corner.


Chas. Freshman Company

Freshman Masterpiece & 5-F-4

Charlie Freshman entered the radio business at the right time, made a lot of money and then got out of the business to spend that money. Starting in 1922, Freshman began selling radio parts and then moved into fully assembled radios when the Neutrodynes started coming out (late-1923 for the FADA.) Designed to look like the typical Neutrodyne, Freshman's radio, the Masterpiece, sold for half the price at $60. If you wanted it as a kit, the cost was only $17. Freshman's engineers utilized the losses of mounting the RF stage inductance directly onto the metal frame of the tuning condensers to prevent the RF amplifier stages from oscillating. This was Freshman's approach, build as cheaply as possible. It worked, too. At its production height, Freshman was turning out over 1000 radios a day. Only after the novice radio buyer got a chance to listen to a neighbor's real Neutrodyne radio did he then realize how badly the Freshman Masterpiece performed. Reliability was also an issue with Freshman Masterpiece radios with defective interstage transformers and potentiometers being the worst offenders. As Freshman evolved as a business, his radios really didn't. New cabinets and different tuning dials maybe, but the circuits remained basically unchanged.  >>>

>>>  Freshman used a particularly high ratio interstage transformer that was not only unreliable but even when working provided so much gain that the audio distorted heavily. Most of the transformers used 6:1 ratio or even higher while the industry standard was 3:1. By 1928, Charlie Freshman was forced out of the company and Walter Chrysler infused some cash into a merger of Freshman and the Freed-Eisemann Company. While the Freed-Eisemann name was used for the high-priced models, EARL was used for the Freshman models. EARL lasted a year or so, until late-1929 brought on the Stock Market Crash.

Freshman made a lot of radios. While they are very common, it is rare to find one that hasn't had some repairs made to it. After all, the parts were just about the cheapest that Charlie could find. The upper right photo shows the typical 1924 Freshman Masterpiece. Supposedly, if the "Freshman Masterpiece" logo isn't present under the switch, then that particular set was the kit version. I've only seen one FM without the logo, so not too many buyers opt'd for the kit.

Shown to the left is the later version of the 5-F-4 model. Earlier versions had external dials while the later version have the dials behind the small windows. This model sold for $49 - really cheap. What is unusual about this particular 5-F-4 is that it is all original and functional. The distortion from the audio is unbelievable due to the 8:1 ratio interstage transformers with no -C bias. Even one of the contemporary radio magazines stated that Freshman's business relied on inexperienced buyers that eventually learned that they had been "taken" by Charlie.




 AMRAD was the American Radio and Research Corporation. Though founded with J. P. Morgan's money, he never ran the company. However, after his father's death in 1913, Morgan's son ran AMRAD. Despite having access to a lot of money, AMRAD always was a "technologically backwards" company that never seemed to be on the "cutting edge" of radio. It was just luck that they became one of the original members of the "Independent Radio Manufacturers" and were licensed to produce Hazeltine-Neutrodyne receivers in 1923. However, in an amazingly incompetent decision, AMRAD didn't offer their Neutrodyne receiver immediately. Instead, they waited over a year and even then delayed their Neutrodyne's introduction until the Christmas season of 1924. The decision to delay their Neutrodyne cost AMRAD thousands of potential sales and the company lost a tremendous amount of money and any respect they had within the radio business. Six months later, AMRAD was bankrupt.

The AMRAD Neutrodyne is somewhat different that the normal layout with one Neutrodyne RF amplifier, Detector and three stages of audio amplification. AMRAD also decided to build the receiver very compactly resulting in one of the smallest of the 1924 Neutrodyne radio receivers.  The Neutrodyne was the last model AMRAD produced before the company went bankrupt (June 1925) and was subsequently purchased by Powel Crosley. By purchasing AMRAD, Crosley was then able to legally produce Neutrodyne radios.


The earliest of the Synchrophase receivers with no chain-drive and no Tone Color control - from late 1924. The initial Synchrophase only had one tuning range, tuning from about 500kc up to about 1300kc. In 1925, a band switch assembly was added that allowed for two tuning ranges allowing tuning from 500kc up to about 1800kc. The 1926 changes were for improved audio reproduction. The Synchrophase was produced from late-1924 up until April 1927. Estimated production is over 150,000 Synchrophases built in that time.

A.H. Grebe & Company

 "Synchrophase"  MU-1

Arguably, the Grebe Synchrophase is best performing TRF AM Broadcast battery set that was made in the mid-twenties. The circuit was a Neutrodyne and Grebe was sued by Hazeltine (Independent Radio Manufacturers) because of it, though production of the MU-1 was never stopped and continued on, ultimately reaching over 150,000 radios. The MU-1 is very sensitive and will separate signals quite well due to its SLF (Straight-Line-Frequency) condensers and binocular coils. The construction of the binocular coils prevented an EM field from being radiated and eliminated stray coupling between the RF stages. The remaining interelectrode capacitance of the RF amplifier tubes was "balanced out" with feedback condensers (which Grebe called "Balancing Condensers.) Grebe engineers considered the MU-1 Synchrophase's great performance was due more to the design and construction of the unique precision components used in the receiver rather than the Neutrodyne circuit.

The earliest Synchrophase receivers use a single filament control and a volume control that selects various resistors that are across the second audio interstage transformer primary. The small round escutcheons only had "INCREASE" embossed on them. Shortly after "VOLUME" and "FILAMENTS" were added to the "INCREASE" on the small round escutcheons. These early Synchrophases only tune up to 1300kc. Several improvements were added in a mid-1925 production upgrade but the most significant improvements were the ball-chain drive for single-dial tuning and the bandswitch that allowed increasing the upper end of the tuning range to 1900kc.  The bandswitch was actuated by the center dial at either end of its rotation. The chain-drive could be disabled by loosening the knurled nut on top of each outer dial. This would not affect the operation of the bandswitch but allowed for more accurate tuning of the signals. Other mid-1925 additions or upgrades included a "TONE COLOR" control that was actually modified from the old "VOLUME" control. The "TONE COLOR" was now an adjustable resistive-capacitance device installed across the primary of the second audio interstage transformer. The "VOLUME" control was a modification of the old "FILAMENTS" control that changed the component into a dual filament control that separated the detector and AF filaments adjustment from the RF amplifier tubes adjustment, providing better response for receiver output.

A mid-1926 upgrade added an improved audio interstage transformer that increased the "low frequency" response to improve the sound quality. Also part of the 1926 upgrade was changing the audio output tube to a UX-112A, requiring an increased B+ of +135vdc and an increase in the -C bias to the audio output tube to -9vdc. Additionally, the "TONE COLOR" control was changed to a selectable capacitance that shunted the 2AF audio grid to -C. Somewhat after the mid-1926 upgrade a cushioned detector socket was added and, shortly after that, all of the sockets were changed to the cushioned-type. There were no other upgrades after the mid-1926 changes and the MU-1 continued in production until around April-May of 1927. Throughout production there were minor changes to the hardware and assembly, e.g., some sets are found with two lid props and some with just one. Additionally, the dial escutcheons were usually finished in lacquered gold but supposedly some MU-1s had gold-plated escutcheons. Front panels will be found with either linear faux graining or burl (mottled) faux graining. The instruction cards are found in various colors, cream with black letters, yellow with black letters and cream with red letters depending on the vintage of the set. To this day, Grebe's serializing of the Synchrophase remains a mystery. The serialized identification consists of four letters, e.g., "TFZH" or "BWDC", etc. - the letters were not chronologically arranged and defy any sort of decoding. It seems likely that the intent was to obfuscate the actual number of MU-1 receivers being built (at least by serial number inference) since that total built quantity might have figured in a settlement in the pending Neutrodyne suit. Included with the purchase of a new Grebe MU-1 were "Dr. Mu" QSL cards that allowed users to send reception reports to broadcast stations they received on their MU-1 (in the hopes of receiving a return reply QSL card from the BC station.) "Dr. Mu" was an advertising character that Grebe created - a fictitious ancient Chinese philosopher-scientist. "Mu" refers to µ or mu, the gain of a vacuum tube. 

There was also an MU-2 available that was a dry-cell tube version initially using six UV-199 tubes. Later versions used four UV-199 tubes and one UX-120 tube. Another option was a Battery Base that the Synchrophase would set on top of. The Battery Base was designed  for the 1924 version of the Synchrophase that used four +22.5vdc B batteries. By mid-1925, two large +45vdc B batteries were now specified and these wouldn't fit into the Battery Base due to their height. Owners could still operate their 1925 set on the four +22.5vdc B batteries since the voltage requirements hadn't changed. When the 1926 version added the UX-112 tube with +135vdc B voltage the set now required three large +45vdc B batteries (beside two C batteries) and there was no way to fit all of the batteries in the Battery Base. However, by 1926, there were smaller +45vdc B batteries available that would fit into the base but their useful life was much shorter than the larger B batteries. Around this time, the Battery Base was rapidly loosing any desirability as an option. Due to the later battery requirements, most original Synchrophase and Battery Base combinations that turn up are the earlier 1924 to mid-1925 versions. Note that the cabinet feet must be removed from the Synchrophase cabinet in order for it to set flush into the Battery Box recessed area.

The court case regarding the Neutrodyne Patent infringement was heard in June, 1927. Grebe lost the case but was able to obtain a Neutrodyne license almost immediately. However by this time the MU-1 was obsolete and Grebe production was moving to single-dial receivers, the Synchrophase AC-6 and later the AC operated AC-7. The Synchrophase MU-1 production had run from mid-1924 up to mid-1927 and an incredible 150,000 receivers had been produced during that time. 

On an additional note: Some Synchrophases will be found with a greenish-gray color to the finish (as seen in the top photo.) This is a reaction that the original finish has with excessive exposure to sunlight (UV.) The original finish was medium walnut color (as seen in the lower photo.)

For the ultimate information source on the Grebe Synchrophase MU-1, including chronological listing of engineering-production upgrades, restoration hints and neutralizing the MU-1, go to "A Guide to the Synchrophase MU-1." Link below in Navigation Index.


photo above:  Grebe MU-1 CTPB with optional Battery Box. This MU-1 does not have the chain drive and has the "VOLUME" and "FILAMENTS" controls - no "TONE COLOR" control.

photo above: This advertising label was installed inside the cabinet wall on the right side. This label advertises Grebe's Broadcast Station WAHG and also mentions the packet of Grebe QSL cards that were supplied with each receiver.


Federal Telephone & Telegraph Co.

Type A-10 "Orthosonic"

Federal was able to become one of the Independent Radio Manufacturers and was able to sell Neutrodynes. The A-10 is Federal's entry-level Neutrodyne selling for $75 in 1925. Like all Federals, the A-10 is well-built with quality parts, most made by Federal themselves. The Neutrodyne circuit helps the A-10 performance but since the condensers are not "straight-line-frequency" types, all of the stations seem crowded at the upper end of the tuning range. Sensitivity and selectivity are good as expected from a Neutrodyne.

This Federal A-10 has had an interesting history that started in Bodie, California - the mining town located 9000 feet above sea level just north of Mono Lake. The last resident of Bodie left in the 1930s. Much of the town had burned down earlier (although many buildings survived the fire) and the abandoned town was left to decay in the high altitude elements. Below Bodie, at the north end of Mono Lake, the Scarvino family had a ranch. By the 1940s, going up to Bodie to "pick thru" the remains was popular with the locals. Supposedly, this A-10 was picked-up by one of the Scarvinos (along with a Cameco horn speaker) and brought back to their ranch. Fast forward to the 1990s, when I picked up this A-10 (and the Cameco horn) from the person that got it from the Scarvinos. It's obvious by the A-10's condition that the radio must had been inside one of the many surviving houses in Bodie (from the mid-1920s up to the 1940s.) In 1964, the state of California made Bodie a State Park and a full-time ranger is now always on duty in town. When visiting Bodie it's hard to imagine that the structures that have survived represent only about 10% of what Bodie was in it's heyday.


Stine Electric Store - San Francisco


By late-1924, all radio fans had been hearing names like "superheterodyne," "neutrodyne," "thermiodyne," etc., mentioned in all of the radio magazines or in other advertising. The variations of names ending in "dyne" was almost endless. But, here's one more,...the "REX-O-DYNE," or, the "King of the Dynes." Not that there was ever much innovation in the circuits, most were standard TRF using what was more-or-less a public-domain type of circuit so that the radios really weren't of much interest to the lawyers from the IRM or the Radio Group. However, Stine Electric Store was located in San Francisco, California and that location was important for those who wanted to build radios and probably avoid any sort of patent litigation. The major patent holders weren't very concerned with any radio manufacturing going on west of the Mississippi, so California radio builders had pretty much free-reign to build whatever circuits they could get away with. Most of the western radio builders didn't have enough sales to warrant any patent infringement worries from the big eastern radio companies.

Stine Electric Store was probably a small shop that dealt in "all things electric" and certainly radios would have been part of their sales. The "REX-O-DYNE" is obviously built from easily obtained components. Even the cabinet was a purchased piece. In the 1920s, it was fairly popular for a small "radio" store with a talented owner to build a few radios to sell every so often. The engraved front panel might have been "farmed out" and the cabinet purchased but the radio itself looks like it was probably built at the Stine Electric Store. Workmanship is fairly crude, especially fitting of the radio chassis into the cabinet. The radio's exterior, however, is exquisite. 

The "REX-O-DYNE" circuit uses three tubes in a "double-reflex" circuit. Reflexing was first described in the 1923 LeFax Radio Handbook as a method of routing a RF signal through an amplifier tube and then routing the audio signal through the same tube. Since the frequency difference was substantial, there was little interaction between the two signals and the tube amplified both signals simultaneously. The "REX-O-DYNE" has one 201A tube functioning as both a First RF amplifier and a First AF amplifier while a second 201A tube functions as the second RF amplifier and second AF amplifier. The third 201A tube functions as the detector. Usually only one tube is reflexed in this type of circuit but it is possible to use two stages of reflex operation. This essentially has a three tube receiver actually functioning as a five tube set.   >>> 

>>>    The audio output is routed to a built-in horn speaker that looks like it was salvaged from an old Wurlitzer battery set. Another interesting circuit in the "REX-O-DYNE" allows it to operate on the AC line, although this is probably a somewhat later addition. The power supply is located in the left compartment and is contained within a cardboard box. It's a nice cardboard box that has a black leatherette finish to it. Interestingly, a type UX-112A tube is used as the half-wave rectifier in this circuit (grid tied to plate.) The RF coils used are flat, "spider-web" type, low-loss coils. Thordarsen interstage transformers are used. Most reflex radio circuits date from around 1924 but some of the components in this REX-O-DYNE seem a bit later although these later components might be from updates added later in the radio's life.

GE and Westinghouse for RCA

Radiola 20

Why RCA offered the Radiola 20 is a mystery. RCA was practically the only company that sold superheterodynes and here they were offering a TRF front-end with a Regenerative Detector followed by two stages of audio amplification. Certainly by 1925, the Regenerative receivers had fallen out of favor with AM Broadcast listeners who didn't like the interference caused by their neighbor's regen-set when it was oscillating. However, some realized that the regen-detector was about the most sensitive detector of the day. RCA added two stages of RF amplification in front of the regen-detector which isolated it from the antenna and eliminated that possibility of interfering with your neighbor's radio.

The Radiola 20 tuning condenser is ganged together to provide single-dial tuning but two trimmer condensers allow for fine tuning for best accuracy. Regeneration is labeled as "Amplification." The two pin jacks on the right side of the panel are for an external filament voltage meter. Using four UX-199 tubes and one UX-120 tube, the Radiola 20 is a surprisingly good performer. The UX-120 is run at +135vdc with a -22.5vdc bias and the RF stages are also biased with -4.5vdc. Several different B+ voltages are required for the circuit to perform as designed. When operated correctly and with a good quality cone speaker, the Radiola 20 sounds good and is very sensitive. Note that the escutcheons on this Radiola 20 are the early versions that were given a "gold wash" - sort of a very thin gold plating. Later versions of the Radiola 20 have bronze finish escutcheons that are much darker.



Model 20 "Big Box"  &  Model 20-C  "Compact"


Atwater-Kent liked the appearance of his components and his breadboard sets reflect his opinion. However, consumers in the mid-1920s - at least those that weren't "technoids" - wanted enclosed radios that didn't show any of the tubes and wires that radio enthusiasts enjoyed looking at. Additionally, there were the "electro-phobics" that were always afraid of anything running on electricity and to them the exposed terminals of the breadboards caused no end of concern.

A-K finally enclosed the breadboard design in a mahogany cabinet with a metal front panel that was painted brown crystaline enamel (A-K's name for "wrinkle finish") and the set was designated the Model 20.

The early version Model 20, aka, "Big Box"

The later version Model 20, aka "Compact"

Today's collectors have dubbed this first version the "Big Box" in contrast to the later Model 20-C or Compact. The 20-C reduced the size of the cabinet to the absolute minimum as there is very little space inside the cabinet that isn't radio components. A battery cable is brought out the rear of the 20-C cabinet to allow the set to be connected to batteries. Terminals inside provide connections for the horn speaker and the antenna-ground system. The 20-C was popular and A-K sold a lot of them. High quality components and good performance as was typical of Atwater-Kent.

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. The American Beauty was installed into several variations of cabinet construction. Some will be found with slanted panels, others with vertical panels. Also, the depth dimension doesn't seem to have been consistent with the deep cabinets probably intended for battery storage.


American Bosch Magneto Corporation

Bosch "Little Six" -  Model 46

American Bosch started out as the Robert Bosch Magneto Company in the early 1900s. It was owned by the German Bosch company that was founded in the 1880s. The Robert Bosch Magneto Company was seized during WWI under the War Custodian Act and the company sold to American investors who renamed the company "American Bosch Magneto Corporation." This was the Bosch company made radios in the twenties. Their Amberola was a good seller and probably the best looking of any of the Bosch radios. Most of the later Bosch radios are rather plain and simple looking which has resulted in most of these later Bosch radios being ignored by collectors.

The Bosch Model 46 "Little Six" is a six-tube, TRF, battery-operated radio. It has a single dial tuning with illuminated dial. The thumbwheel tuning was becoming popular in the late-twenties although it never seems to allow easy tuning of any stations. Filament controls are the lower knobs although they are marked as "Clarifier" and "Volume." There were two versions of the Little Six. One that has the all-wood front and the other that has a painted metal overlay (brown wrinkle finish.) The same control layout and escutcheons are found on either version.

Selling price was $68 in 1927.


F.A.D. Andrea, Inc.

FADA 6    Model 460

Frank A. D'Andrea was the first Neutrodyne licensee of the Independent Radio Manufacturers and his company, who had been making crystal detectors, became the first to offer a Neutrodyne receiver to the public in late-1923. D'Andrea had actually shortened his name to Andrea some time earlier and had several jobs before going into radio. During WWI, he was associated with DeForest and by 1920 had his own company producing crystal detectors. A law suit over crystal detectors caused Andrea to broadened out to complete radios and kits after becoming a member of the eleven Independent Radio Manufacturers. Around late-1925, Andrea hired engineer Lewis Clement who designed a series "high-end" Neutrodyne receivers. The same basic "cost-no-object" design principles were incorporated into six, seven and eight tube chassis that were then installed into many different types of cabinetry. These "over-built" radios were expensive and provided "top-of-the-line" performance. The radios were complicated to "hook-up" employing battery cables that had at least ten different battery connections. In the late-twenties, F.A.D. Andrea, Inc. was purchased by  investors and went bankrupt in the early thirties. Frank Andrea had already started Andrea Radio Corp. by that time and that company continued in business for decades.

The FADA 6, Model 460 is a six-tube Neutrodyne receiver that came out in 1926, selling for around $150. Ruggedly-built with completely shielded tuners that allowed the RF amplifiers to operate without any stray coupling. The 460 has a tuned antenna stage, three Neutrodyne TRF amplifiers, a detector and two stages of audio amplification. The audio output tube is a UX-112A running +135vdc on the plate. The fold-out loop antenna was mounted to the left side of the radio cabinet. There was also optional connections for using an "outdoor" antenna, if desired. If the loop wasn't used then it could be folded down and would stow under the lid.


photo above
: FADA 8  Model 480 with Western Electric 540AW 18" cone speaker

F.A.D. Andrea, Inc.

FADA 8   Model 480,  a.k.a. Model 480-A

Selling for $300 in the "table model" version, the FADA 8  Model 480 was the largest of the Lewis Clement-designed, massive, Neutrodyne receivers from 1926. At 32" wide, 15" deep and 14" tall along with topping the scales at 80 pounds, the FADA 8 is a behemoth. Everything a radio fan could want and could afford was installed, including a built-in, fold-out loop antenna, a front panel meter that measured the filament voltage and could also, by rotating the "Meter Switch," measure any of the four B+ voltages. Additionally, the number of audio stages used could be selected from the front panel. The new UX-171A audio output tube could operate with up to +180vdc on its plate providing thunderous volume. The audio output +180vdc B+ is coupled to the UX-171A plate thru a choke and the audio output is coupled to the loud speaker using a 1.0uf capacitor. This eliminates the B+ from appearing on the loud speaker terminals. With an excellent condition and well-designed cone speaker, the audio is powerful and impressive.

The FADA 8 uses one stage of tunable antenna amplification, three stages of Neutrodyne TRF amplifiers and one Detector stage. Each RF stage is fully shielded as is the detector stage. A two-piece metal box comprises the shield for each stage. All three AF amplifiers are within one shielded box. Each tube has its own shield cap that fits to the top of each shield box and completely shields each stage. Heavy cast "howl supressors" were available for the audio tubes and the detector tube to prevent microphonic feedback. Each stage is fully bypassed with fixed-value capacitors.

The two tuners adjust the Antenna (left control) and the Wavelength (right control.) The loop performance is incredible for such a small antenna but there is so much gain available there is no disadvantage to using the built-in loop when it is deployed in the upright position. With an full-size outdoor antenna, the Antenna control will usually have little effect due to the high inductance but reception is generally improved over the loop.

While certainly some 1926 owners ran their FADA 8 receivers on batteries, the manual suggests that a FADA-Philco ABC Battery Eliminator can be used. Some FADA 8 receivers were installed into larger and more elaborate console cabinets, of course, at much higher selling prices. In 1927, the FADA 8 was redesigned to eliminate the panel meter and simplify the front panel controls. When introduced, it was called the FADA 8  Model 480-B and the earlier Model 480 was then referred to as the Model 480-A.

The FADA 8 shown in the photo to the left is fully functional. It did require rebuilding of the meter switch, rebuilding one shorted bypass capacitor and some minor repair to the loop. I power the FADA 8 using a RCA Duo-rectron for B+ requirements, a small adjustable dual power supply for the two -C requirements and a 6V 4A Lambda power supply for the A supply. Performance is incredible and the audio doesn't even sound like a battery-era radio.


E. M. Sargent


Building a superheterodyne in the late-twenties was a risky-business. If the radio's performance was great and the sales substantial then it was very possible that Westinghouse, GE, RCA and the Radio Group lawyers would threaten a lawsuit to stop production. Sometimes a location on the West Coast would provide distance and isolation from the Radio Group's interest but a good radio with a lot of public interest was sure to foment a reaction from the Radio Group's lawyers. One way around all of the superhet problems was to offer the radio as a kit. Since construction of a superhet kit limited interest to radio enthusiasts with a talent for construction, sales were never going to attract the attention the superheterodyne patent-sales protection lawyers of the Radio Group. Another protection plan was to obfuscate exactly what the radio circuit accomplished, thus confusing the patent-busting lawyers. E. M. Sargent took both approaches with his Infra+Dyne receiver.

E. M. Sargent was a small radio builder located in Oakland, California. In 1926, he produced a radio kit that was promoted as "a new circuit" with "quiet background noise and great sensitivity." The radio circuit was called the Infra+Dyne, a name certain to confuse any non-technoid lawyer. Sargent also published a few booklets on the Infra+Dyne that explained all of the radio's design ideas without ever mentioning the word "superheterodyne" in any of the text. However, the Infra+Dyne is an up-converting superhet. The famous Remler Infradyne Amplifier is basically a three tube IF amplifier. That it operates at 3500kc is something unusual - the normal superhet of the day probably used around 125kc IF (since those all down-converted.) The fact that the IF is a product of up-converting, the LO has to tune "backwards" in order to keep both dials seemingly having similar readouts. Ten tubes are used in the Infra+Dyne circuit. A mixture of both UX-199 tubes and UX-201A tubes are utilized. Two RF amps, Mixer, LO, three IF amps, detector and two AF amps comprise the tube lineup. The coils in the front end were originally specified as Thorola Toroid "Donut" coils but later Silver-Marshall coils were recommended. Remler was usually the source of the tuning and LO condensers. Jewell supplied the filament voltage meter, National Co. supplied the vernier tuning dials on many examples and Thordarson was usually the audio interstage transformers of choice. Since the kit was essentially the plans, schematics, blueprints, booklet and some of the unique parts, like the IF section - the Infra+Dyne Amplifier, or the front panel and several other parts specific to the design. Many of the other parts or custom changes had to be purchased. These purchased parts account for the variability of construction in all of the examples of Infra+Dyne radios.

When operational, the Infra+Dyne does work quite well. The 3500kc IF does result in a very quiet background noise and the addition of the two RF amplifiers results in adequate sensitivity - at least for the AM BC band. Several different voltages are required to power up the Infra+Dyne. Unfortunately, the actual receivers are quite large. With ten tubes and an IF strip that's sixteen inches long, most Infra+dynes end up being very long radios.

I've owned two Infra+Dynes. The first was a professionally built one labeled as a "Remloc" and it's shown in the photo to the left. It was built in San Francisco. Clearly, it violated the superhet patent since it was sold as a complete, ready to operate radio. However, being in California did provide most small radio-building operations some protection due to the distance between them and the Radio Group lawyers in New York City. The Remloc did function and, after a bit of adjustment to the IF strip, it provided decent performance. It had been built using Thorola "Donut" Toroid Coils. It had a fabulous cabinet and a red mahogany bakelite front panel. The dial scales were illuminated on the Pilot vernier dials. Unfortunately, I sold the Remloc several years ago.

My currently owned Infra+Dyne is shown in the top photo and it was positively built as a kit. Construction is fairly good but certain areas show the amateur-quality found in most kits. This Infra+Dyne is built with Camfield Duo-Coils (binocular types that perform similarly to toroids.) Whether there ever was a cabinet for this Infra+Dyne is unknown. I found as it is, sans cabinet.


Kemper Radio Laboratories

Model K-5-2

In 1928, Sennett Gilfillan and David Sarnoff* met in New York to come to an agreement as to how radio manufacturing in the West would develop. Prior to this time, many small companies were building radios that technically violated many of the patents held by the "Radio Group." Since the radio sales in California didn't really compete much with the radio sales East of the Mississippi, the Radio Group was never too interested in pursuing any suits against the small operations in the West. But, as radio manufacturing grew in the West, the Radio Group, or at least RCA, wanted some type of control of that growth and to profit from the radios sold in the West. The specifics of the agreement are covered in the write-up on the Gilfillan GN-3 (above.)

After the RCA-Gilfillan agreement, Gilfillan had the exclusive licenses for radio building for all eleven Western states. All radios that were built in those states had to have Gilfillan involved in the approval, construction and collecting licensing fees/royalties (5% of the radio's sale price to be split between Gilfillan and RCA.) Eventually, all Western radio manufacturing (that was considered legal) was done at the Gilfillan plant in Los Angeles, California. This method of radio manufacture in the West continued all through the thirties. It changed the radio-building landscape and limited all Western radio manufacturing to just the Los Angeles area. Remler, in San Francisco, was allowed to operate probably because of their relatively small output. Small operations that only produced limited quantities of radios were of no interest to RCA or Gilfillan, so there are examples of Western-built radios that turn up once in a while that didn't go through the licensing structure. The quantity of these radios built was always limited to just a few.

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 is the early "pre-Gilfillan" name of the company. In 1928, it became Kemper Radio Company going though Gilfillan for radio construction.  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.

* David Sarnoff was General Manager of RCA at this time. The actual president of RCA was James G. Harbord, who had been president since Ed Nally Jr. retired in late-1922. By 1927, Harbord was probably leaving the day-to-day operations to Sarnoff. In 1928, Harbord took a leave-of-absence from RCA to campaign for Herbert Hoover in the upcoming presidential elections. After the election, Harbord continued on as RCA's president up until he retired in January 1930. David Sarnoff then became the president of RCA.

Custom-Built Glass Case Neutrodyne Radio

Built by: E. H. Browning, June 20, 1927, Portland, Oregon

Radios that were built into cabinets made of glass served two purposes. First, for the radio parts dealer, it displayed what type of components were available and how they would look in a home-made radio. It's also possible that some dealers actually would build custom radios and the glass cabinet again showed the typical construction and layout of components. There were also instances where a special glass case was used for display of a radio company's model (used by dealers) that would show potential customers the internal construction of the particular model (this use was fairly uncommon.) The second use was a talented "homebrewer" that just wanted to show his building prowess with a radio that was uniquely different. Certainly Glass Case Radios are seldom encountered. They are rare because there were so many problems involved in using glass as a medium for the construction that few were ever built. Today, Glass Case Radio survival depends on the durability of the cabinet to withstand the effects of time, poor storage, careless moving and neglect. Also, the chassis must have been able to survive similar conditions. Most Glass Case Radios date from the mid-to-late twenties. They shouldn't be confused with the glass-mirrored radios of the thirties that were produced by true radio factories (Sparton and some others.) The Glass Cased Radios were built specifically to "show off" the construction and components of the radio circuit, either for dealers or for enthusiastic homebrewers.

The Glass Case Neutrodyne Radio shown above dates from 1927. It was built using primarily components made by the Bremer-Tully Company (B-T.) Six tubes are used in the Neutrodyne circuit, three RF amplifiers, a Detector and two stages of transformer coupled audio amplification. The RF coils use chokes that isolate them from B+ (chokes are made by B-T.) The neutrodyne feedback capacitors are also B-T as are the B-T "TOROSTYLE" (toroid) RF coils.* The dual-section tuning condensers each have an additional trimmer condenser. The tuning dials are National Type B Velvet Verniers. The audio interstage transformers are 4:1 ratio on the 1st AF and 2:1 ratio on the 2nd AF and both are B-T Type T-210 "EUPHONIC" transformers. All of the tube sockets are Type 349 General Radio sockets except for the cushioned detector tube socket which is made by the Benjamin Company. Audio output is accessed via the front phone jacks and the operator can select either one or two stages of AF amplification. Power is supplied by batteries and these are connected via binding posts on the rear of the chassis with the exception of the C bias battery which is connected with flexible wires.  >>>

>>>  The radio is physically rather large at 32" wide and 13" deep. The chassis is made of bakelite. The glass pieces are held in brass channels that are screwed together or soldered to form the glass cabinet. The base is redwood. Fortunately, this Glass Case Neutrodyne Radio was signed and dated by the builder (which is somewhat unusual.) On the bottom of the wooden base written in pencil is "Bilt (sic) by E.H.Browning, June 20, 1927, Portland, Oregon."

*The toroid style coil form will not radiate an EM field and therefore will not couple to an adjacent RF stage via stray coupling. This leaves only tube interelectrode capacitance coupling that is "balanced out" using the Neutrodyne feedback condensers. The neutrodyne provided high gain and high selectivity without RF stage oscillation.


Crystal Sets


Uncle Al's Radio Shop

"Miracle" Crystal Sets

Uncle Al's Radio Shop built the best performing and certainly the most selective crystal sets available in the 1920s and early 1930s. The crystal sets were sold mainly in the West and most often in California's San Francisco Bay Area. Uncle Al was actually Alex Forbes, who, along with his brother, Henry, built and sold uniquely designed crystal-detector receivers during the 1920s and 1930s out of Oakland, California. Uncle Al's Radio Shop probably started out at either Alex's or Henry's residence in the 1920s. Most of the early crystal sets will have an address on the paper tag under the lid with one of two locations shown, either on Dakota St. or 27th Ave in Oakland. Later locations are at 3905 Hopkins St. in Oakland. Whether Alex Forbes had an actual radio shop (doing repairs and sales) in the early twenties is unknown. By the early 1930s, he was doing business out of a shop location on Hopkins St. that did advertise service and sales.

The Miracle Crystal Set uses multiple coils with fairly loose coupling with variable condensers for sharp tuning. The resulting selectivity is a "Miracle" with Uncle Al's crystal sets having tuning that acted like the popular TRF battery sets of the mid-twenties. Most crystal sets of the time used either "self-resonant" coils that shorted turns for tuning (like Philmore) while others merely had an LC on the antenna with a diode detector, capacitor and phones (some homebrews.) Both of these types of crystal sets will receive multiple stations simultaneously due to their lack of selectivity. Uncle Al's circuit used loose coupling combined with bucking coils for selectivity along with tuned input and tuned detector pick-up coil for better sensitivity. Uncle Al's tuning circuit made the "Crystal Set" a radio receiver that could separate several broadcast stations received within a local area. By 1925, when Uncle Al was introducing his No.1 type, the AM BC band was unofficially 550kc up to 1500kc and within an area like the San Francisco Bay Area several broadcast stations were operating by that time. The Uncle Al's Crystal Set would be able to separately tune each of those stations - something a Philmore or Lemco couldn't do.

The "Miracle" shown in the photo is a No.1 version probably from the mid-1920s. It has two antenna binding posts, the upper is for shorter wavelengths and the lower is for longer wavelengths. The tag under the lid has an address of 27th Ave. which is later than the first sets from Dakota St. but it is still the No.1 type. Uncle Al's cabinets are not finished or they might have been coated with a thin shellac finish that normally is not present on examples found today. Supposedly the wood used for the cabinets is eucalyptus which is very common in that area of California. Uncle Al was always improving the "Miracle" so it wasn't long before the No.1 was replaced with the No.2 with its rotating spider-web detector coil with an adjustment knob between the two tuning knobs. The crystal-detector used on both the No.1 and No.2  was similar to those made by Grewohl although they are from a different source.

Uncle Al's Radio Shop is still in business in Oakland, California, (though they now sell and service TVs.)

Thanks to Dan Merz for all of the Uncle Al's Radio Shop history.

The photo right shows a late-1930s Uncle Al's Radio Shop promotional card. Note that the card states "MANUFACTURER OF OVER 10,000 SETS - SATISFACTION GUARANTEED!" 


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.


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.

There was also another crystal set that is almost identical to the Betta-tone, built by Lemco in San Francisco.


Philmore Mfg. Co.


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 components used are all mounted on the back of the unfinished metal panel. Some examples of the "Blackbird" have a "crazed" painted front panel that usually appears to be gold in color. Later "Blackbirds" changed the metal case to heavy cardboard. Shown is an early Philmore from the late-twenties or early-thirties. By the 1940s, Philmore crystal sets had molded plastic cases.


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, homemade crystal sets abounded with popularity and several examples can still be found (they're still popular to build today.) Common materials used for the homemade set's coil form 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, though most builders were content with just a wooden board to mount the parts on. The crystal set shown was built by M.H. Dodd probably in the early 1920s. Dodd's circuit is unusual in that a tuning condenser is used BUT it's tuning the primary of the coil. The secondary is untuned. Performance is, as expected, quite poor. I'm sure Dodd was thinking of much earlier wireless hook-ups where tuning the antenna primary was considered important, as in many pre-WWI types of tuners. It became more common to tune the secondary with an air variable capacitor after WWI..

We have several Dodd pieces including his Homebrew Three-tube Set, his AK-40, this Crystal Set and his complete 1912 Wireless Station - for details on the Wireless Station go to "M.H. Dodd's 1912 Wireless Station" in the navigation Index below.


Early AC Radios (1927-1929)



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 Model 37 production was finished in a brown wrinkle finish called "Crystaline Enamel", sometime in the production year of 1928, a small number of Model 37 radios 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 was achieved by using stencils and a light spray painting technique - something like "air brushing."  The finish was very thin and thus was subject to much wear. It's very common to find "Modernistic Style" cabinets with a lot of chips and scratches. Originally, the paint on the "Modernistic Style" was not a glossy finish but was more of a "matte finish" or "semi-gloss." There are two variations of the Type-E speaker. When the "Modernistic Style" matching speaker was fitted with the "thin wood" type of cone, the cone was painted flat black. When the "Modernistic Style" matching speaker was fitted with the thick embossed paper cone, the cone was painted silver. The Type-E speaker shown above has the paper cone and is all original with its proper silver paint. Estimated production is around 10,000 radios, which for Atwater-Kent was a "small run." Today, the "Modernistic Style" is rarely seen. Fortunately, most examples that turn up seem to have the matching Type-E speaker still with the radio - probably because it's pretty obvious that the two pieces went together. This particular "Modernistic Style" was originally purchased in San Francisco and for years made its home in San Francisco's "Chinatown."

Recently (2012,) the television show "American Restorers" featured a "Modernistic Style" radio as one of their restoration projects. Besides several factual errors being presented as expert knowledge, the restoration itself was inaccurate and incomplete. I suppose stating a few times that the radio was a 1926 model was just an oversight by the writers but even the most novice of radio collectors would know that the major introduction of AC-operated radios was announced in late-1927 and that most production examples are actually from 1928. The melting out of the black wax in the power supply box was accomplished with a propane torch - very funny. Most restorers would have used a small oven (like a "used" toaster oven) to slowly melt-out the wax (or maybe even used the old freezer trick.) Plastic wire used in the restoration was inexcusable since there are many sources for the correct original type wire. While the new paint job was stunning, it was finished off with several "clear coats" to make the end-result super glossy - beautiful, but not very accurate. The panning close-up shots of the cabinet revealed a missing Dial Index piece. These are easy to find (or replicate) - why was it left off? The vacant holes above the tuning dial should have been a clue that something was mounted there. Perhaps the most incredible part was the cost of the restoration - $1100 - Wow! Like most of what you see on television, "American Restorers" is an entertainment program and what is presented there should not be taken as expert advise or even correct information - especially when it comes to radios and radio restoration.


Model 40

The Model 40 was one of the most popular of the metal boxed, AC-operated radios produced A-K. Probably, the reason that so many have survived is that the radio was built like a little "tank." There might be problems that develop in the power supply which is filled with hard wax. This makes repair of the power supply somewhat difficult. However, many Model 40 still operate fine on all-original parts. A-K made all of their own components and most of them were high-quality parts. The 1928 A-K Model 40's circuit is TRF and uses seven tubes.

The Model 36 was the first AC-operated radio from A-K in 1927 and the Model 37 was the first AC-operated metal box radio with built-in power supply (and the Model 35, a six-tube battery set from 1926, was the first A-K metal box radio.) Arthur Atwater-Kent felt that the mahogany wooden cabinets he had been making cost too much to manufacture. He knew that a stamped steel cabinet would be cheap to make. It could be painted which was also cheap and easy to do. He just had to convince would-be radio purchasers that these painted steel boxes were stylish and would fit in with the late-twenties decor. With a lot of advertising, A-K was able to change the tastes of radio buyers and the metal box radios became quite popular for a short time, about 1928 up to 1930. A-K even sold a console radio in a metal cabinet. Today's tastes are very different and many collectors find all of the metal box radios ugly, regardless of who the manufacturer was.

The A-K Model 40 shown belonged to M. H. Dodd and was acquired along with Dodd's 1912 Wireless Station in 1999. This Model 40 has the earlier style tuning dial. Later versions have larger numbers and a different style grip. While the Model 37 top tag depicted the Mayflower (or, at least a sailing ship,) the Model 40's tag just has "ATWATER-KENT" embossed on it.



  Screen-Grid Model 55

One of the last of the stamped metal box TRF radios from Atwater-Kent, the Screen-Grid Model 55 uses type 24-A tubes. These are tetrodes which have more gain than the type 26 triode tubes used in earlier models. The Model 55 also uses an electro-dynamic speaker, housed in a round metal cabinet that is mounted to a small pedestal. The design of these speakers are very close to the speakers used in all later radios consisting of a field coil magnet and a low-Z voice coil with paper cone. Some of the construction is slightly different in that a separate suspension is used around the rim but basically the A-K speaker is modern in design. Sound quality (for a 1929 table radio) is very good.

The Model 55 was a departure for A-K in the paint finish. Unlike the earlier metal boxes, the Model 55 is painted with high-gloss lacquer. This particular one is in black and green, however sometimes black and red was used. Since the finish was smooth and glossy, it's very unusual to find any Model 55 that's in good condition, cosmetically anyway. Most examples are severely chipped because the smooth lacquer didn't have the durability of the heavier wrinkle finishes. The Model 55 shown is the best condition one I've encountered. There are a few chips where the speaker sat on top of the set but otherwise it's in excellent condition. Nice cosmetics really doesn't help since most collectors still find these metal box radios hideous looking.



Radiola 60

RCA's "tour de force" superheterodyne, the Radiola 60, was certainly the best performing superhet available in 1928. AC operation, 9 tubes, powerful sounding audio from a single-ended 71-A, cathode type 27 tubes used in the rest of the radio with the exception of the type 80 used for the rectifier. The Radiola 60 was well-built and today many still function quite well on all original parts. The weakest point of the radio is the multi-tap wire-wound resistor used to reduce voltages for various functions. Since this puts the B+ in a series string, if any section of the resistor opens, then the radio will not function. It's easy to repair by installing a correct value WW resistor across the open section. With an outdoor antenna, the Radiola 60 will pick-up just about any signal on the AM BC band. Unfortunately, RCA didn't include a calibrated dial, the Radiola 60 uses a 0-100 scale on the tuning. Two types of escutcheons are found on Radiola 60s - dark bronze, as shown in photo and also, black with silver lettering.

There were a few different speakers available for the Radiola 60. The Radiola 100A was a metal "mantle clock shaped" that sounded quite nice. The speaker shown in the photo left is the Radiola 103 "Tapestry" Speaker. The frame of the speaker is made out of "repwood" or sirocco, a pressed wood that could be molded into any shape. This was then stained. The speaker mounts to the back of the frame and then a cardboard cone was mounted behind the speaker. The cardboard cone was covered with very fine brown cloth. For not having a true cabinet, the Radiola 103 sounds surprisingly good.

The first vintage radio that I bought for myself was a Radiola 60. I was fourteen and paid seven dollars for it (in 1964.) It was a consolette Radiola 60 sold by Sherman-Clay in 1932. Sherman-Clay had bought "left over" production Radiola 60s (very cheap in 1932.) They then had a local California cabinet shop build the console base and install a Jensen Concert Dynamic Speaker. These radios were then sold as "new" models in 1932. The Jensen speaker does make the Radiola 60 sound like a 1930s console. And,...yes,...I still have this Radiola 60 consolette some 55 years later.

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