The first production of the 51S-1 occurred in August 1961 when three units were completed just before the end of fiscal year 1961. There is a tuner shield with holes for alignment and a tube stage on the left.įigure 2 – 51S-1 Receivers – Prototype on the Left It has a five fluted Megacycle knob (Early production 51S-1 were the same and then it was changed to four flutes). The rear panel connections are different. The prototype cabinet is a modified KWM-2 cabinet (obvious from the rear). Under the hood things are similar but different in a few areas as shown in Figure 2 where the prototype on the left is placed beside a 1963 winged emblem production model for comparison. The meter switch is labeled “RF, Line 1, Line 2” (The prototype had two line audio outputs). The “Rejection Tuning” scale has expanded tic marks. The noise blanker knob is located where the production logo was later placed. The Collins logo is located above the phones jack. The “Zero Set” knob is round like the S/Line instead of the small “bar” type used in production. In addition to the main tuning knob, a list of other changes includes: Arlo Meyer, W0LBK, told me they wanted the feel of a weighted knob for tuning but it was going to turn an extensive gear train. The main tuning knob is machined from solid brass and painted black. For example it has a noise blanker although the module was missing from the chassis. One can see several items that are much different than the production versions we are used to seeing. So I did some minor cleaning and then put it on display in the Rockwell Collins Museum.
But after further thought, I decided it was really a historical artifact and shouldn’t be tampered with. I accepted of course and spent some time examining the unit, taking photographs, and even contemplating restoring it to operating condition. Several years back, an engineer from Ed’s 51S-1 team retired and asked me if I would be interested in the prototype 51S-1 receiver. Jerry Vonderheide, W0NGL, later created the 51S-1A – a version powered from 28 Vdc for aircraft operation. It was none other than Ed Andrade, W0DAN – The same fellow who earlier brought forth the Collins 51J-4 and the KWM-2! All three equipments were in production far longer than the average Collins HF equipment – a testimony to the solid design and outstanding performance achieved by Ed and his engineering team. I would like to acknowledge the project engineer who led the design of the 51S-1 receiver.
Collins 51s 1 re update#
This article is an update – along with some additional information and insight added. I published the results on the reflector and, in the years since, I have continued to gather additional data from other sources. The project was designed to shed light on the many questions collectors had about production quantities, anomalies, scarcity, etc. A number of years ago I conducted surveys of Collins ham equipment on the CCA reflector.
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