John Eng's Dead Tech Rescue

Transistor Radio Collections

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COLLECTIONS

Page 1: The Beginning THE BEGINNING 1954-1958

Page 2: USA and Canada Brand Radios 1959-1960's USA AND CANADA 1959-1960

Page 3: Japanese Imports 1959-1960's JAPAN 1959-1960'S

Page 4: Transistor Radios 1970-on TRANSISTOR RADIOS 1970 -ON

Page 5: Novelty Transistor Radios SPECIAL PURPOSE SOLID STATE RADIOS

RESTORE IDEAS AND HISTORY

Links to Restoring Transistor Radios: RESTORING SYLVANIA TR

Links to Transistor Radio Videos on YOU TUBE: 1955 MAKING TR- THE REGENCY TR-1

Page 1

The Beginning 1955-1958 Made in the USA

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Early RCA (1956-58) Transistor Radio with woman demonstrating portability and lightweight.

The Transistor was invented in 1948. In less than 20 years it made the vacuum tube a dead end technology. It paved the way to the integrated circuit and the micro chip found in computers, phones etc. Still from 1948 to the early 1970's transistors like tubes were discrete parts in electronics. Shown below are transistor radios that are part of electronics history.

To see the World's First Transistor Radio watch the video at this link PRODUCTION OF 1954 REGENCY TR-1

In 1954 Regency made the TR-1 "The World's First Transistor Radio"
Made in the USA. A 4 Transistor Radio using all Texas Instruments Transistors.

1954-1956

The First All Transistor Radios

Raytheon 8TP1 to 8TP4- 1955 (World's 2nd transistor radio and Raytheon's 1st). (P1= tan leather, P2= brown leather, P3= beige leather, P4= red leather) Price in 1955 $79.95.A 7 Transistor Radio

Raytheon made their own transistors CK760, 2N130, 2N133 and 2N138.Raytheon built this radio like military equipment. The battery compartment chassis is anodized against battery corrosion. Battery contacts are silver plated and the transistors are mounted on sockets. Very heavy set. The leather case is wood backed for durability.

Completely restored electronically. All original electrolytics restuffed with new ones. All resistors out of tolerance replaced. The radio has been retuned and aligned.

RCA 7-BT-10K (1955) one of RCA's first transistor radio along with the plastic case 7-BT-9J
A 7 Transistor Radio
RCA made their own transistors but used some TI transistors 234 and 235 the rest are RCA 2N109. Price in 1955 $75.

RCA 8-BT-XXX, Radio Corporation of America, Camden NJ. Model year: 1956 -57(XXX code: 8JE= Charcoal Cabinet, 7LE= Green Cabinet and 8FE= Pink Cabinet,). 7 has no earphone jack (named Winsome) and 8 has earphone jack (named Stetson).
A 4 Transistor Radio

The Stetson can be identified with the lighter color tuning dial, along with nan earphone jack. The Winsome has a copper color tuning dial.

They came in three colors- pink, charcoal and aqua.

RCA made their own transistors and used 2x 2N109, 2N139 and 2N140 transistors. Unlike the earlier models, RCA cut out extra transistors to make it more affordable, Price in 1956 $39.99 for Winsome and $44.95 for Stetson.

ABOVE: Stetson with all original parts.

Zenith Royal 500, CH 7XT40 (hand wired version) 1956 (Zenith's 1st transistor radio).

A 7 Transistor Radio
Used Sylvania transistors 2N35, 2N193, 2N194 and 2N216.

Top view shows metal plate used to mount coils, transformers and transistors.

Hand wired!

Raytheon T-2500- 1956 the Fourth and Last Transistor Radio by RaytheonA 7 Transistor Radio
Same basic circuit as the 8TP series, but has a pair of 4 inch speakers. Made for the beach or park.

Raytheon made their own transistors, CK760, 2N130, 2N133 and 2N138

Two four inch speakers connected in series. A rare twin speaker portable before stereo boom boxes. Gives a lot of sound dispersion.

Raytheon T-2500.mp4

ABOVE: Watch the T-2500 1950s Boombox

ABOVE: Top view shows the similarity to the Raytheon 8TP chassis. BELOW: Restored underside. All the electrolytics restuffed with new electrolytics. The emitter bias resistors shown over the bank of electrolytics are way off tolerance were replaced.

Emerson 849 (1955) Emerson's 1st all transistor radio
Used TI type transistors using Emerson custom #s 815009 (2N145), 815010 (2N147), 815017 (2N172), 815018
A 6 Transistor Radio

Emerson used a hand wired chassis

GE 675 to 678 (1955)General Electric's 1st transistor radio
A 5 Transistor Radio
GE made their own transistors using 2N44, 2N78, 2N135, 2N136 and 2N137. Prrice in 1955 $49.95

Philco T-7-126 (1956) (Philco's 1st Transistor Radio)
A 7 Transistor Radio.
Philco designed their own transistors 5021, 5028, 5114 and 5113

Zenith Royal 500, CH 7ZT40 (Printed Circuit Version) 1956-57. Zenith toward the end of the model year switched to printed circuit board construction.

A 7 Transistor RadioComparison of the hand wired early version (CH 7XT40) on LEFT and later PC board version (CH 7ZT40) on RIGHT.

Motorola 56T1 (1955) (Motorola's 1st Transistor Radio)
A 5 Transistor Radio

Attractive lunchbox styling, but Motorola used a metal cabinet, that can limit sensitivity. To align the set the radio circuit must be removed from the cabinet to gain access to the tuning capacitor ant and osc adjust screws.. After alignment and reinstall the radio circuit back into the cabinet may detune the radio.

Inside the 56T1 (Motorola used Texas Instruments Geremanium Transistors) 2N172 conv, 2-2N145 IF amp, 2N185 output and R-35 det-amp transistors

To keep cost down Motorola used a class A audio amplifier design. This saved a transistor and a interstage transformer. All the transistors were made by Texas Instruments. To make the radio compact, Motorola used double sided printed circuit board with feed thru holes to go from top layer to bottom layer. Servicing this set can be difficult.

Repairing this radio had all kinds of issues. The big one was the oscillator coil shown in the foreground has a microscopic crack on the ferrite shield. This cause the radio to detune and sometime go dead after a few minutes of running. I put a strap around the shield as shown and now it works.

1955-1956 Hybrid Radios

Using tubes and transistors

Short Lived and Early Production Transistors were expensive. Some manufacturers put in a couple of transistors and the rest tubes to save money and market the radio as transistor. Tube technology made hand wiring easier

Emerson 838 (1955) Purse size and Enerson's first TR. Uses 2 custom made transistors (made by Texas Instruments) and 3 Subminiature Tubes (1V6, 1AH4 and 1JD4). The A battery is a 4 volt mercury battery and the B Battery is a miniature a 45 V type.

Looks like a PC board, but it is a phenolic board that has terminal lugs to perform point to point hand wiring underneath.

Emerson 843 (1956) Lunch Box Size Radio. AKA "Transistor lll" Below is an example of what a hybrid looks like in a tube type leather case. The Emerson 843. Uses 3 miniature tubes ( 1R5, 1U4 and 1U5) and 3 custom Emerson transistors (2N109)

BELOW: Ultra tight wiring. Repairs are very difficult and frustrating. I had two bad IF transformers (upper left), Had to have a lot of patience to remove and reinstall them.

BELOW: Inside the leather case. The two batteries are mounted at the bottom. The only thing that keeps the batteries secure is the sharp curve of the leather case at the bottom.

Emerson Hybrid Sets

Emerson 838Access to alignment of stations requires removal of cover plate above B battery door.

Access to 4 volt A battery

Emerson 843: Three battery tubes on the left and the three audio transistors on the lower right.

To get access to changing tubes or transistors, one must remove the front panel.

Emerson 843 IF Transformer Failures

Common in mid 1950 Radios

BELOW: Both IF transformers suffered from silver rot. Sample of capacitor silver rot.

BELOW: The 1st IF transformer had a broken lead. Open lead and area repaired.

1957-1958

All Transistor Radios

Westinghouse H-612P5 (1957)
A 5 Transistor Radio
Uses Texas Instruments transistors 2N252 RF/Conv, 2N253 and 2N254 IF, 2N238 Audio and 2N291 Audio Output.

ABOVE: Speaker is mounted on a large metal frame. In order to access the components it has to be removed. BELOW: Once metal frame removed the components can be seen.

ABOVE: All the original electrolytic capacitors failed. They were replaced as shown (blue colored)

Sonora TR-280B (black), TR-281B (ivory) and TR-282B (red) "Power Mite" (1957-58)Made by Trav-ler Radio for Sonora.
Along with the model 610 (Sonora's first transistor radio) the Power Mite are the only two transistor radios marketed, as Sonora would shortly close its doors permanently. Sonora calls it a 6 transistor radio because the included the 1N295 limiter diode as the 6th transistor. Used GE transistors 2N107 (or SC-12, a Sonora part number), 2N292/448, 2N1086 and 2N1098/1145
A 5 Transistor Radio

ABOVE: TR-281B

ABOVE: TR-282B

ABOVE: To get to the component side you have to remove metal speaker and tuning frame. The five transistor radio is not very sensitive and mainly for local broadcast reception. BELOW: How the assembly looks when you remove electronics from cabinet.

ABOVE: Recapped

Carrying Case.

Motorola 66T1 with Box- 1956 (Motorola's 2nd Transistor Radio)
A 6 Transistor Radio
Within a year Motorola makes major upgrades to the 56T1. It is now a 6 transistor radio with push-pull Class AB audio amplifier and a separate diode detector and avc limiter diode added. The double sided printed wired board remains.

Same width and height and handle-antenna as the 56T!. The depth is significantly deeper.

Motorola makes the rear deeper to accommodate using 4AA cells.

Compare Model 56T1 (left) vs 66T1 (right)Motorola uses Texas Instruments germanium transistors. 2N172 conv, 2-2N145 IF amp, 2N105 input audio amp and 2-2N185 push pull audio output amp. Motorola replaces the 9 volt battery and now operate on 6 volt with 4 AA cells.

Motorola 6X31 (1957) Motorola 6X32E (1957)
6 Transistor Radios

Motorola switched to GE transistors 2N168, 2N169, 2N186, 2N189 and 2N292 for 6X31and 2N167, 2N192, 2N247, 2N292 and 2N293 for 6X32

ABOVE: Basically the 6X31 and 6X32 vis the same design as the 66T1, but Motorola stretched the case width to accommodate the 4AA cells to reduce the depth of the radio case.

Sylvania 3203GR (1957-58) Lunch Box Size Radio.
Six Transistor Radio (See restoration section for details)
This model clearly describes that American buyers still like the much larger "lunch box" style radios. This was a throwback to vacuum tube portable sets. Manufacturers made transistor radios this size often tauted a bigger speaker which translate to greater volume.Sylvania made their own transistors, 2N194, 2N233A, 2N306
A 6 Transistor Radio

Emerson 868 "Miracle Wand" (1957).
Price $46
A 4 Transistor Radio
Emerson Radio, New York, NY. 4 Transistor Reflex Radio. Looks like a throwback from their tube portables. Comes in many two tone colors and has a 4" speaker. Seems like it was marketed for the younger buyers, very simple design but looks like a big sound radio. The handle doubles as a rotating antenna. Uses Raytheon transistors branded with Emerson part numbers.

Used two large 9 volt batteries connected in parallel. Shown below on bottom right is the size of the original battery. On the bottom left is the equivalent using 6 AA cells.

Hand wired underneath, resembling a vacuum tube set.

Raytheon Cobalt Blue Transistors, compare them with the size of the other components

The audio output transistors are between the gigantic electrolytics and output transformer. If you can see it the output transistor is heatsinked to the chassis.

Admiral 801 (1957) Admiral's 8 transistor model
An 8 Transistor Radio
Used RCA 2N406, 2N410, 2N411 and 2N412 series transistors

Admiral Models 581 (Ebony) and 582 (Mandarin Red) 1958 ($29.95)
A 5 Transistor Radio
Used RCA 2N406, 2N410 and 2N411 series transistors.

This was Admiral's 5 transistor low cost model. If one looks carefully, the cabinet of the 580 series is similar to the 801 series except that the 801 series has a genuine metal trim and a handle that doubles as a stand, while the 580 series has metallic painted lettering and a spot for where the handle could have been.

Layout of the 581 after recap and new output transformer.

From Germany (formerly West Germany)

Telefunken Partner IIK (1957). This was Telefunken's second production transistor radio. Uses 6 transistors made by Telefunken. OC213 RF osc/mix, 2- OC212 for IF stages, 2- OC602 Audio Stage and OC604-spez Power Amp.
A 6 Transistor Radio

Telefunken was founded in Berlin in 1903. They made vacuum tubes since the early days of wireless, followed by radio products for consumer and military use. Telefunken experimented and designed early solid state devices before the invention of the transistor and became an early German manufacturer of transistors in the 1950s.

ABOVE and BELOW: All the electrolytic capacitors have been replaced. One can see the European style resistors, round IF transformers and lots of polystyrene capacitors instead of ceramic types.

ABOVE; Close up of the OC612. This was suitable to handle the 460 KHz . Telefunken had to wait until they could make a reliable IF and RF transistor bedore they could mass produce transistor radio. The development of the OC612 and OC613 in 1957 allowed this to happen.

BELOW: Early Telefunken transistor, the OC604 developed in 1956. Their transistors were designed like vacuum tubes, all glass envelopes. They tend to break if handled carelessly.

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