Receptrad/Radio Receptor Co.

Receptrad Front View

     Victor Greiff, E.E., published a superheterodyne manual in early 1924 detailing the theory and manufacture of the superhet using his new Receptrad (Radio Receptor) parts. My example of the Receptrad was built by Charles A. Dean of Binghamton, N.Y., as proudly engraved on the front panel of the set. Charles A. Dean did a good job of building the set but he didn’t have access to the correct equipment to get it working the way it should have worked. Here are a few particulars of the set:

Receptrad Top View

     Top inside view of the set. The DPDT knife switch on the left side of the radio allows the operator to change from an external loop antenna to an external long wire antenna, with the long wire antenna utilizing an internal antenna coupler. When I purchased this radio it had five brass base tipped UV-201A tubes and one Airline gold glass tube. The brass base tipped tubes were probably five of the original tubes because they all had the same label attached with a date code of Jun 17 1924. All the tubes have good filaments.

Receptrad Top Angle View
Receptrad Antenna Coupler

Antenna coupler. The manufacturer is unknown.

Receptrad Oscillator Coupler

Radio Receptor oscillator coupler.

Receptrad Filter Transformer

     Inside angle view.

Receptrad IF Transformers

     Radio Receptor filter transformer. The builder forgot a very important thing; this transformer should have a .00025 mfd capacitor across the primary and secondary windings to make it peak at the correct frequency!

     Close up view of the first two non-tuned RF-1716 IF transformers. Note that the transformer on the right is identified with a Receptrad nameplate; the other transformers do not show the Receptrad name. It is obvious that the Receptrad transformer came from a different manufacturing lot than the other transformers. The Receptrad transformer peaks at a different frequency than the other transformers.

Type

Peak Freq.

Lower 3 dB

Upper 3 dB

Bandwidth

Relative gain

Pri. ohms

Sec. ohms

#1, filter, with .00026 caps

39.8 KC

31,7 KC

46.1 KC

14.4 KC

16.0

107.1

106.3

#2, RF-1716

48.8 KC

35.2 KC

63.0 KC

27.8 KC

14.8

83.7

283.4

#3, RF-1716

28.0 KC

11.8 KC

54.2 KC

42.4 KC

18.4

135.6

333

#4, RF-1716

46.7 KC

32.3 KC

61.7 KC

29.4 KC

16.4

103.8

276.7

     The bandpass measurements of the IF transformers identified several problems with the set. The filter transformer was measured first and it was peaking at 99.0 KC. Victor Greiff’s book states that the filter transformer is designed to peak at 8500 meters (35 KC), with .00025 mfd capacitors across the primary and secondary coils. The capacitors were not there! I put a .00026 mfd capacitor across each coil and obtained a peak frequency of 39.8 KC. This frequency was better than before but the transformer may still need tweeking.
     The other three transformers, #2, #3, and #4, measured, in sequence, 48.8 KC, 28.0 KC, and 46.7 KC. The #3 transformer was way off mark at 28.0 KC. I thought that the transformer was a bad transformer. Several hours after the bandpass measurements I noticed that the label on the bad transformer was different than the label on the other transformers. The bad transformer was identified with the word Receptrad above the word Radio Receptor Co. I can only assume that one of the original transformers failed and was replaced with a transformer from a different manufacturing lot. The bandpass measurements are recorded in the table below.

     General Instrument tuning capacitor.

Receptrad Tuning Capacitor
Receptrad Front Panel Engraving

     Close up view of the front panel engraving.

     The two Radio Receptor audio transformers.

View of the label on one of the original BBT tubes.

Receptrad Audio Transformers
Receptrad BBT Tube Label

     Charles Anson Dean was born in Ithaca, New York, on February 11, 1881. He was a plumber in the early part of the 20th Century and he started a plumbing business in Binghamton, New York, with Alexander Auchinachie, in June, 1908. The short-lived firm was known as Dean, Auchinachie & Co. On August 12, 1910, Charles participated in a five-mile race at the local Stow Park on a single-cylinder four-horsepower Harley-Davidson motorcycle. Charles was a building inspector for the city of Endicott in the early 1920’s, and became a traveling salesman for plumbing supplies later in the decade. He supplemented his income in the early to mid 1920’s by selling radios and radio related parts. At least one of those radios he built himself (the 8-tube superheterodyne presented here). Charles died of a heart attack at an Endicott garage while having his car serviced on the morning of September 23, 1959.

     William H. Newton, the first owner of the Dean superhetrodyne, was born in August 1894 in Pennsylvania. He was a seamstress at a Binghamton, New York, shoe factory when he purchased the superheterodyne radio from Charles A. Dean. William died on January 20, 1976.

Charles A Dean article Binghamton Press July 12 1924
Charles A Dean advertisement Binghamton Press June 7 1922

Binghamton Press
July 12, 1924

Binghamton Press
June 7, 1922

Charles A Dean Binghamton Press October 7 1909

Charles A. Dean
Binghamton Press, October 7, 1909

May 18, 2018 Update

Receptrad #2

Receptrad Barry front view

     The radio shown above used to be one of radio collector Dale Davenport’s prized receivers. I considered Dale an Internet friend, and I purchased this radio after he passed away. Dale owned the radio for at least 25 years and he entered it in the Antique Radio Club of America meet in Little Rock, Arkansas, in 1994, where it won a first place blue ribbon.

Receptrad Barry top chassis view

     Top view of the chassis. Electrically it is very similar to the Dean Receptrad, except that this set does not have a built-in antenna coupler. Here are a few particulars about the set:

     1. The engraved front panel measures 36” long by 8” high by 1/4” thick.
     2. Radio Receptor Co. oscillator coupler, filter transformer, IF transformers, and audio transformers.
     3. Unknown tuning capacitors, but they are high quality type with geared vernier drives.
     4. Unknown rheostats.
     5. NaAld tube sockets.
     8. Eight tubes.

Receptrad Barry oscillator and input couplers

     Close up view of the oscillator coupler (far right) and the input coupler (filter transformer, lower center). The two tuning capacitors for the input coupler are mounted under the baseboard.

Receptrad Barry tuning capacitor

     Close up view of one of the high quality tuning capacitors with geared vernier drive.

Receptrad Barry IF amplifier

    Close up view of the IF amplifier. All of the transformers are identified as Radio Receptor Co. (none with the Receptrad name).

Receptrad Barry audio amplifier

     Close up view of the audio amplifier. Note that the identification of the battery terminals are engraved on the basepanel.

Receptrad Barry front panel close up

     Close up view of the front panel engraving, indicating MODEL B IMPROVED SUPER-HETERODYNE

Receptrad Barry basepanel engraving

     Close up view of the engraving on the basepanel, indicating IMPROVED SUPER-HETERODYNE DESIGNED BY JAS. A. BARRY 1924

     The table below records the pass band characteristics of the IF amplifier. The input coupler has a .00025 MFD capacitor across the primary and secondary coils (unlike the Dean Receptrad, where the capacitors were missing). The secondary of the first three transformers were referenced to A-. The reference for the fourth transformer was A+ and the grid leak resistor and capacitor were in the circuit.

Type

Peak Freq.

Lower 3 dB

Upper 3 dB

Bandwidth

Relative gain

Pri. ohms

Sec. ohms

#1, filter, with .00025 caps

36.4 KC

30.5 KC

41.4 KC

10.9 KC

13.5

92.3

91.7

#2, RF-1716

31.5 KC

13.9 KC

59.5 KC

45.6 KC

16.0

160.8

324.3

#3, RF-1716

30.7 KC

13.4 KC

55.8 KC

42.4 KC

15.9

155.4

327.0

#4, RF-1716

26.8 KC

14.4 KC

43.5 KC

29.1 KC

11.8

161.0

328.0

 

Receptrad Barry top inside chassis view

     James A. Barry was born on January 26, 1907. He sold Fort Smith Times Record newspapers during World War I. Barry began his broadcast radio career at age 15 at WGAR radio station and at 17 designed and built a radio called the Brown Teletone. He was manager and advertising manager for KFPW in 1930s, two radio stations in Muskogee in the 1940s and manager of KWHN in the 1950s. He died Monday, May 15, 2000. SOURCE: "The Times Record Obituary Archives." Fort Smith, Arkansas. 18 May 2000.; Archived: 30 Mar 2005.

August 9, 2017 Update:

     The following images were scanned from Victor Greiff’s Super-Heterodyne Manual (Receptrad Series No. 1, 1st Edition, forward dated February 20, 1924). This book contains all the theory and full scale blueprints to construct the Receptrad Type SH8-1 superheterodyne.

Receptrad SH8-1 front and rear views

     Front and rear views of the Type SH8-1 receiver.

Receptrad SH8-1 standard panel layout

     Type SH8-1 front panel layout. This is a photo of the original 36” long blueprint. Unfortunately, much of the detail is lost by reducing the original to this small size.

Receptrad SH8-1 standard baseboard layout

     Type SH8-1 baseboard component layout.

Receptrad SH8-1wiring diagram

     Type SH8-1 wiring diagram. The filaments of the three tubes in the IF amplifier are controlled with one rheostat, and the filaments of the two tubes of the audio amplifier are controlled with one rheostat. The first detector, the oscillator, and the second detector each have their own filament rheostat control. The circuit includes a potentiometer to control the stability of the IF amplifier, and a small battery to control the grid bias of the two audio tubes. The first detector does not have a control for regenerative amplification. This is a typical early 1924 circuit. Regenerative amplification in the first detector was added to many superhets later in 1924.

Receptrad SH8-1 AF and RF transformer

AF and IF transformers

Receptrad SH8-1 Oscillator coupler
Receptrad SH8-1 Tuned Filter Coupler

Oscillator coupler

Tuned filter transformer
(The Dean set did not have the capacitors)

Receptrad ad CRCB Fall 1924

     Radio Receptor advertisement from the Fall, 1924, Citizens Radio Call Book.

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Receptrad Front View