Patterson Model 127 -- No Ordinary Radio

BY BILL MOORE AND HARDY TROLANDER

WEB EDITION

In this article, Moore and Trolander describe a high performance radio for the home that has its roots in the world of Amateur Radio and SWL. Patterson, a producer of communications receivers during the 1930s, applied its know-how to the design of the Model 127. Its parentage is apparent when the radio's dial scale is compared to that of the Patterson Model PR-15 communication set. (Editor)

The variety and complexity of vintage radio collecting never ceases to intrigue. This article highlights a receiver manufactured by Patterson, a company better known for its communications receivers than for its consumer radios. Comunications sets such as Patterson Models PR-10, -15 and -16 ring bells for those familiar with Ham radio. The company's experience with professional Ham/SWL equipment was reflected in its consumer products, as explained in this article.

Figure 1. The front view of the Patterson Model 127. This allwave radio covers the frequency range of 545 kHz to 20 MHz.

Company Background

The Patterson Company touted in early ads that it had been in business since 1919. However, its first advertisement did not surface until 1922, and that was for a crystal set. According to advertisements, Patterson was active in the late 1920s and early 1930s, and these sets are not only to be found, but are fairly well documented.

Several are depicted in John Stokes' radio books, and New Zealand seems to have been the recipient of quite a few of the early 1930s sets. Although these early 1930s cathedrals are around, if you look hard enough, they are not at all common. Introduced in 1933, the Model PR-10 shortwave receiver was the company's first, and perhaps most successful venture into the Ham/communication receiver market.

Floyd Paul indicates in his book Los Angeles Radio Manufacturing that a large part of the Patterson production was destined for the Far East, and may explain the scarcity of many of its models here in this country. If we move on to the mid-to-late 1930s era, Patterson home/broadcast sets get extremely few and far between. Patterson shut down sometime in 1939 so its production period was not very long-lived.

In personal discussions with Don Dotson, former engineer for the company from 1935 to 1938, we learned that Patterson was a healthy company. Don was the head line engineer for Patterson until chief engineer Karl Pierson left to help form a new company and began selling the Patterson Model PR-15 communication receiver under the Pierson-Delane name. All Patterson sets were still produced at the Gilfillan plant.

Patterson intended to get out of the communication receiver business when its designs were sold. Most Patterson sets were built for operation on a 220-volt, 50-cycle line supply, thus slated for a substantial overseas market. New Zealand always got a large part of the production, according to Don Dotson. Patterson also produced OEM sets for Western Auto, under the Western Air Patrol name.

As some of you may know, there is a severe lack of advertising and other information from which to draw conclusions on the later Patterson models, especially the home receivers. Mark Stein in his second table model book depicts some of the Patterson AC sets.

Market Demand for Large Table Allwave Sets

The news on shortwave bands from faraway places and the war threatening in Europe all contributed to the demand for radios to get the latest news from overseas. The market for large allwave table sets was a very limited one as indicated by period advertisements, set production totals, and the number of surviving sets today.

These radios were seldom purchased in the U. S. as the primary radio in a household. What the little advertising of the period indicates is that they were purchased as secondary radios for the bedroom or the den, and the primary radio was a console set in the living room. This is in contrast to many other countries where the available home area for a radio was less, and the main radio was usually a table model. The export market for large multiband sets was more demanding, since some companies repackaged console chassis in table model cabinets and sold them only overseas.

We know this situation in England and continental Europe where consoles are scarce. In the U. S., the primary purchaser of the large, multiband table radio would be from the upper middle class and above, a fact which limits the number and variety of sets being sold.

General Configuration and Features

Some of the features hyped and demanded by the consumer in an allwave set during the Golden Age of U.S. receiver manufacture included the following:

• RF stage
• Multiple IF stages
• Beat frequency oscillator (BFO)
• Push-pull output
• Ease of tuning, and large easy-to-read dial
• Stability and accurate dial settings
• Allwave coverage
• Band spread tuning
• Reliability
• Latest tube types
• Tuning indicator
• Variable RF sensitivity and other controls
• Looks didn't seem important. Most sets were larger and uglier than the lower line sets, with few exceptions.

Market and Economic Considerations

The United States was coming out of a severe depression in the mid-to-late 1930s and people wanted their money's worth. In addition, labor was cheap compared to the post-war economy, and craftsmanship could be obtained at a fraction relative to today's prices. However, the latest technology was still expensive, and the design development of upper market radios was difficult. The manufacturer had to keep a profit margin while balancing features, retail cost, and market share.

The nature of this market led to most manufacturers having invested much of the cost of the high-end table radio in the chassis. In order to keep prices down, and with only a small total run of sets to amortize the cost of the cabinet design, most sets of this type lacked style in cabinet appearance. There are exceptions to this rule, but they are few.

Even with the relatively few choices and the less than enthusiastic interest of the manufacturers in producing the large, high-tech, multiband table sets, some good ones were produced; for example, the Fada 212, the Zenith 835 and 12S232, the RCA 10T, the Philco 116, and others. However, one set in this category stands alone, and outshines them all -- the Patterson 127.

Unique Features of the Patterson 127

The Patterson 127 used 12 tubes of either glass or metal octals in an allwave table model for home enjoyment. Wow! There are no "ringers" or tubes in parallel, etc.; every one serves a specific purpose. The Patterson 127 is no ordinary radio.

Let's start at the antenna connection and work our way through the set to its speaker. Two tuned RF stages employ Type 6K7 tubes to provide image-free reception from 545 kHz to 20 MHz. It is not likely that any allwave table model could match its performance. The use of a Type 6L7 first detector and separate Type 6K7 oscillator resulted in very stable operation on even the highest band. Tuning is aided by an all-geared dial drive with mechanical band-spread dial. Thus, the dial may be set or reset very precisely.

Figure 2. This rear view of the Model 127 shows its orderly component and tube layout.

Two stages of IF amplification using Type 6K7s employ IF transformers with three windings each in the first two transformers. These are switched by a knob on the front panel of the set to provide both broad and narrow selectivity for higher fidelity audio response or greater selectivity for better shortwave reception where channel separation is only 5 kHz. High fidelity reception is frequently impossible as a result of interchannel interference.

The diode sections of a Type 6Q7 provide the second detector function, and its triode section is the first audio amplifier. The first audio is the driver for the push-pull Type 6F6s that power the set's loudspeaker providing around 12-watt peak power. Rather than use a phase inverter stage or a common interstage transformer to provide both the coupling and phase inversion from the Type 6Q7 to the Type 6F6, Patterson used a "balanced autoformer" -- a special form of auto-transformer -- for the same purpose. The set's power supply used a Type 5X4 rectifier and its power transformer could be connected to match either 115- or 220-volt lines to meet the Patterson requirement for export business.

A Type 6G5 "magic eye" helped the user to tune the set more accurately and the last tube of the set's 12-tube complement was a Type 6C5 "beacon," Patterson's term for a beat oscillator (BFO). The BFO is turned on and off by a switch on the back of the chassis. An RF gain control is also located on the back of the chassis, as are connections for a phonograph pickup and power-line fuse.

Most wiring is bundled and tied, making for a very neat servicing package, and free of the common appearance of "spaghetti-ing" under the chassis.

More Model 127 Details

The Patterson is likely the only allwave superhetrodyne table radio to employ two fully tuned RF stages on all bands. Only top-of-the-line consoles such as those produced by McMurdo Silver and Scott or communications receivers such as Hammarlund, etc., employed this feature. Higher signal-to-nose ratios and image-free reception are the result. Thus the effective sensitivity of the Patterson likely surpassed that of any other table radio.

As mentioned in the circuit description of the Model 127, two of the IF transformers contain tertiary windings switched so that, in one position, full-fidelity reception is obtained, while in the other position, the narrow bandwidth needed to separate adjacent shortwave stations is achieved. Also in the narrow bandwidth mode on shortwave, the ability of the tone control to attenuate the lower audio frequencies will generally improve the intelligibility of voice transmissions.

The tone control for the Model 127 is a type rarely, if ever, found in a table model radio. The common version found in most table radios includes a potentiometer and a capacitor that functions as a treble cut-off. The Model 127 employs both a capacitor and a choke connected to opposite ends of the tone control so that it acts as both a bass and treble control.

When the control is centered, there is no bass or treble attenuation. Rotating it to one end of its travel attenuates the higher tones while the lower tones are attenuated at the other end of its travel. Control of the lower tones is the unique feature that aids crisp reproduction for greater clarity when receiving voice communications.

Coupling between the first audio and the push-pull final stage is accomplished by a balanced autoformer (autotransformer). The Patterson's autotransformer consists of four separate windings interleaved to provide the balance not usually achieved by the more commonly found autotransformer consisting of a single center-tapped winding. This feature is relatively expensive, rare and may be unique to several Patterson models only. It is indicative of the extra engineering effort that went into the designing of this remarkable radio.

The physical appearance of the set is attractive with a large dial and solid walnut knobs that are easy to use and placed ergonomically. The attractive orderly chassis layout is shown in Figure 2.

The Patterson is roughly a contemporary of the McMurdo Silver Masterpieces V & VI, and early Scott Philharmonics. In terms of sensitivity, selectivity, background noise level and frequency stability, it is the equal of the Scott and McMurdo Silver radios. It is a bit easier to tune on the high bands since its dial provides just a little more resolution than the other sets and with less backlash than that of the belt-driven sets.

All four of these receivers include two tuned RF stages, and that accounts for their very high performance, especially on their shortwave bands. Needless to say though, the massive audio amplifiers and speakers found in the other sets overwhelm the output of the 8-inch Jensen speaker found in the Patterson.

In summary, the Patterson Model 127 is a very powerful and exceptionally well-balanced allwave receiver. In contrast to most other table radios of its day, it contains no shortcuts and employs what were then "best practices" in both its design and construction.

References:

Paul, Floyd A. Los Angeles Radio Manufacturing. Glendale Cal.: Floyd A. Paul, 1988.

Personal discussions with Don Dotson, Summer, 2001.

Stein, Mark V. Machine Age to Jet Age, Volume 2. Baltimore: Mark V. Stein and Radiomania Books, 1997.

Stokes, John W. The Golden Age of Radio in the Home. New Zealand: Craig -- Printers and Publishers, 1986.

(Bill Moore, 901 Spanish Oaks, Huntsville, AL 35803; Hardy Trolander, 1475 President St., Yellow Springs, OH 45387)

Bill Moore has been a Defense/Aerospace Systems and Missile Systems Engineer since 1984. He began collecting unusual cathedral and tombstone radios in 1978. He specializes in prewar Pilot and other large deluxe model radios.

Hardy Trolander, founder and CEO of YSI Inc., is a member of the National Academy of Engineering and a Senior Member of IEEE. He is a Fellow of the American Institute for Medical and Biological Engineering and a Founding Member of the International Institute for Medical Electronics & Biological Engineering. He has 15 patents covering semiconductor processing and semiconductor networks.