 |
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.) 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. |

|
General Electric
for RCA
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
- a.k.a. 10-B
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. Shown is the 1924,
Model 4560 (A-K 10-B) in standard finish, (black paint on the cans.) 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. 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. There are many
variations and different models of breadboard sets that were 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 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. |
|
 |
|
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" were 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 interelectrode capacitance which then
allowed for higher gain without oscillation instability. 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. Many 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 sales price of the intended purchase.
Consequently, 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. |
|

|
AMRAD
Neutrodyne
AMRAD was the
American Radio and Research Corporation. Though founded with J. P.
Morgan money, Morgan's son ran the company after his father's death in
1913. AMRAD never seemed to be on the "cutting edge" of radio
technology. It was luck that they became one of the original members of the
"Independent Radio
Manufacturers" and was licensed to produce Hazeltine-Neutrodyne
receivers in 1923. However, for some reason AMRAD didn't offer their Neutrodyne receiver immediately
though, delaying introduction
until the Christmas season of 1924. The delay cost AMRAD any advantage
they had as a Neutrodyne producer and the company lost a tremendous
amount of potential sales.
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 |
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.
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 seem to defy any sort
of decoding. 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 used based on the then popular conception of
an ancient Chinese philosopher-scientist and "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 using six UV-199 tubes. 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. 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: 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.
photo left: 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. |
|
|

|
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.
Go to our section
"Classic Pre-WWII Ham Gear"
to see a complete 1933 two-tube receiver and four-tube transmitter, both
with separate AC power supplies, all built into a
Kemper K-5-2
cabinet - it's impressive. Navigation link at bottom of this page. |

|
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. |
Crystal Sets
 |
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 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. |

|
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 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, homemade crystal sets abounded with popularity
and several examples can still be found. Popular 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, 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. |
Early AC Radios (1927-1929)

|
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." |
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Western Historic Radio Museum
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P.O. Box 73
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