Colonial 31 and 32 D.C. Superheterodyne Receiver
Radio Service Data Sheet
September 1930 Radio-Craft

September 1930 Radio-Craft

[Table of Contents]

Wax nostalgic about and learn from the history of early electronics. See articles from Radio-Craft, published 1929 - 1953. All copyrights are hereby acknowledged.

Colonial 31 A.C. Superheterodyne Receiver Radio (RadioAttic.com)

The following announcement was posted in the September 1930 edition of Radio-Craft magazine regarding Radio Data Service Sheets. Oddly, I don't recall knowing that the "Radio Service" part of Radio Service Data Sheet referred to the name of a company/publisher. They must have been like an early version of Sam's Photofact subscription plan. Radio-Craft continues to produce the Data sheets for many years.

"We are pleased to announce that RADIO-CRAFT has taken over the subscription list of 'RADIO SERVICE,' formerly published in Dallas, Texas. All subscribers of record to RADIO SERVICE will receive RADIO-CRAFT until the expiration of their subscriptions."

I could not locate a photo of the Colonial Model 31 / 32 "DC" radio, but did find a model 31 AC (thumbnail to the left). The DC and AC models likely used the same chassis, with the only difference being the AC operated off line current and DC used a battery. Up until the Tennessee Valley Authority (TVA) was established later in the 1930s, most rural areas did not have AC electric service and relied on banks of storage batteries and/or local AC generators for power, so many radio manufacturers made DC versions of their products. Notice in the schematics that there are no input transformers, only DC line noise filters.

Colonial 31 and 32 D.C.

The Colonial "31 D.C." which has had very wide distribution, incorporates a number of unusual design features. For instance, volume is controlled by varying condenser C4; with the middle plate centered the signal is balanced out. An absorption loop (LI C) improves the tuning characteristic. The cable color code is as follows: 7, yellow; 1, maroon; 5, black; 2, blue; 6, red; 12, gold with black tracer; 9, black with red tracer; 10 red with black tracer; 3, green; 4, 8 and 11 are not used. VI, V2, V3, V4 and VS are '26 tubes; V6, V7, are '71As; while V8 is a 110 V. "miniature base" 15 watt lamp ...

Posted October 30, 2023
(updated from original post on 7/4/2016)

Radio Service Data Sheets

These schematics, tuning instructions, and other data are reproduced from my collection of vintage radio and electronics magazines. As back in the era, similar schematic and service info was available for purchase from sources such as SAMS Photofacts, but these printings were a no-cost bonus for readers. There are 255 Radio Service Data Sheets as of April 30, 2025.

RF Electronic Stencils Symbols Visio Shapes Office

RF Cafe began life in 1996 as "RF Tools" in an AOL screen name web space totaling 2 MB. Its primary purpose was to provide me with ready access to commonly needed formulas and reference material while performing my work as an RF system and circuit design engineer. The World Wide Web (Internet) was largely an unknown entity at the time and bandwidth was a scarce commodity. Dial-up modems blazed along at 14.4 kbps while tying up your telephone line, and a lady's voice announced "You've Got Mail" when a new message arrived...