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Early Vintage Hewlett-Packard Oscillators 1938-1941 by Kenneth A

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Early Vintage Hewlett-Packard Oscillators 1938-1941 by Kenneth A Early Vintage Hewlett-Packard Oscillators 1938-1941 by Kenneth A. Kuhn August 4, 2008, rev. 6, Aug. 22, 2009 This is an article in progress. Revisions will be made as more information is discovered. Introduction Many people who have acquired or found a vintage HP oscillator have inquired to the author as to whether that oscillator could have been built in the famous garage. The answer is always no. Only a very small number of oscillators were built in the garage and typical oscillators people own have characteristics that prove that they were constructed years after the garage days. However, a recent inquiry had enough credible characteristics to inspire the author to explore deeper into the history of the oscillators and write this article. It turns out that it is almost a certainty that that oscillator was built in the garage and the author is very glad to have been able to analyze detailed pictures of it. A picture of the front of that oscillator is shown in Figure 1. It probably has been repainted at some point as the normal color was gray like shown in Figure 4 and the red fill in the engraving was probably added by some owner over the years as every example of engraved panels the author is aware of are unfilled. The original metal output binding posts have been replaced by more modern plastic versions. The author is aware of at least four of the small case units in existence. Figure 1: A recently discovered garage vintage oscillator (photo courtesy of Cal Taylor) The purpose of this article is to provide all of the known information (which is not very much) concerning the earliest vintage oscillators built by the Hewlett-Packard Company. 1 Early Vintage Hewlett-Packard Oscillators 1938-1941 The early oscillators were made in four case sizes. The first oscillators from late 1938 to the roughly fall of 1939 were made in what I refer to as the small case with rounded corners which is 13” wide and shown in Figures 1 and 4. Oscillators made between the fall of 1939 and up to early 1941 were in what I refer to as the large case with rounded corners which is 16” wide and shown in Figure 16. Oscillators built from early 1941 are in the rectangular case which is 15.25” wide as shown in Figure 17. Any rack mount case is 19” wide and could have been built from 1939 onwards – a sample is shown in Figure 5. The complete dimensions are in the summary at the end. The majority, if not all, of the small case oscillators were built in the garage. The majority, if not all, of the large case oscillators were built at the 481 Page Mill Road / El Camino locations. A summary of the early history Bill Hewlett discovered the light bulb solution to stabilizing the Wien Bridge oscillator on July 27, 1938 (1). In the fall of 1938, Bill built an oscillator based on this design as part of his master’s thesis in Electrical Engineering at Stanford University (located in Palo Alto). Figure 2 is of the front of that oscillator now housed in a glass case at the HP Archives. The red and black output jacks are probably not the originals. Those likely wore out and were replaced at some time. Although the frequency dial resembles later 200B units (making one wonder if the original has been replaced) it is unique to this instrument and Bill must have custom made it. Figure 2: Bill’s first Wien Bridge Oscillator at Stanford University (photo courtesy of the Hewlett-Packard Company – from web site) 2 Early Vintage Hewlett-Packard Oscillators 1938-1941 Bill and Dave and his new wife, Lucile, moved into the house on 367 Addison Avenue in Palo Alto in the fall of 1938 (2). The location was chosen because the garage could be used as a shop and there was also a small building in the backyard where Bill would live. Dave and Lucile lived in the house – see Figure 3. A state historical marker can be seen in the front yard. The famous garage can be seen behind the gate. Figure 3: Restored HP house and garage (photo by Ken Kuhn) During late 1938 and part of 1939 Bill and Dave did some odd contract work including a foul line indicator at bowling alley, a synchronous motor drive for the telescope for Lick Observatory, and a self flushing toilet. This provided a little bit of income. (3) Late in the year of 1938 the design of the model 200A was finalized and a prototype was constructed. In order not to advertise that this was their first product, the oscillator was given the model number designation of 200. The prototype was shown at the Portland IRE show in November, 1938. Bud Hawkins, the chief sound engineer for the Walt Disney Company, attended the show and was impressed with the oscillator – particularly the low price of less than one hundred dollars. Later (probably in early 1939), Mr. Hawkins contacted HP for a special version of the oscillator as discussed below. (4) 3 Early Vintage Hewlett-Packard Oscillators 1938-1941 In December, Bill and Dave built another prototype in a more professional looking case. This prototype sat on the mantel over the fireplace in the house and a picture of this exists. They prepared a two-page sales brochure and sent it to a list of about twenty five contacts provided by Fred Terman. According to Bill, the first advertised price for the 200A was $54.40. That value was based on the phrase, “54’40” or fight” that was used in the 1844 campaign to set the U.S.-Canadian border in the Northwest. That price was kind of a joke amongst Bill and Dave and was not profitable. The price was later revised upwards to a profitable $71.50. (5) Bill and Dave signed the business agreement that began the Hewlett Packard Company around Jan. 1, 1939 and they began formal operations. Early in 1939 orders for the 200A began to come in. Early oscillators were built in a purchased enclosure (small case with rounded corners). It is believed (but the author has not yet found the proof) that these enclosures were manufactured by Bud Industries, Inc. (a.k.a. Bud box). (6) On July 5, 1939, Bill and Dave donated a model 200A to Stanford University. That oscillator is now on loan to HP and resides on the mantel over the fireplace in the restored house where the first HP200A sat – see Figure 4. The author has had the privilege of a tour of the house and garage and has seen that oscillator. The small plaque below the nameplate reads, “PRESENTED TO STANFORD COMMUNICATIONS LAB.” In the photograph you can see a clear plastic cover around the unit to protect it from being touched. (8) Figure 4: Small case with rounded corners 200A oscillator (photo by Ken Kuhn) 4 Early Vintage Hewlett-Packard Oscillators 1938-1941 The famous model 200B was a simple modification to the 200A requested by Mr. Hawkins from the Walt Disney Company for use in tuning theater audio systems for the upcoming move, Fantasia. Disney needed frequency coverage down to 20 Hz. The modification consisted of using larger resistances in the tuning network so that the frequency range of the 200B was from 20 Hz to 20 kHz whereas the frequency range of the 200A was from 35 Hz to 35 kHz (although the dial on some early units went to 40 kHz). The author has seen the only known picture (at the Agilent History Center) of the 200B units at a Disney lab and these were in the rack mount case (another modification requested by Disney) rather than the often seen desktop case. Figure 5 is a picture of a vintage 200BR model with the pre-logo nameplate just like those sold to Disney . The main chassis of the oscillator is identical to the rectangular case but the front plate is 19 inches wide to permit mounting in a standard rack. Chuck House has done some research that shows that the famous sale to Disney consisted of nine 200B units at $57.50 each. (13) The author has not found any information as to whatever became of these units as none are known to exist. (7) The author has not seen it but apparently there is a 1971 picture showing at least one of these oscillators at a Disney lab. Rack mount HP equipment includes the suffix ‘R’ in the model number to indicate rack mount. Thus, the units sold to Disney are really 200BR although it is not known if the suffix was first used in 1939. Figure 5: HP200BR S/N 478 similar to those sold to Disney (photo by Tim Souza) 5 Early Vintage Hewlett-Packard Oscillators 1938-1941 Figure 6 shows a close-up of the name plate on early HP oscillators like the one in Figure 3. This nameplate style was used from the earliest oscillators up to early 1941 when the new HP logo was introduced. Any HP equipment that does not include an HP logo and has a nameplate similar to that in Figure 7 was definitely manufactured prior to 1941. Figure 6: Pre-1941 name plate prior to introduction of HP logo (photo by Glenn Robb) Figure 7 shows a typical nameplate for equipment made between 1941 and 1945 and also shows the first logo for HP introduced in early 1941. Any HP equipment that includes an HP logo was definitely manufactured from 1941 onwards.
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