[Milsurplus] history and evolution of the Collins gear

[Al Klase]

Folks,

The post-war Collins receivers were a radical departure from almost 
everything that came before in that you could set the dial to a desired 
frequency, and be certain you were within a kilohertz or two.

"If you want to find them use a Collins.  If you want to listen to them 
us a Hammarlund." :-)

The basic architecture is a crystal controlled converter in front of a 
carefully calibrated tuned IF.  The IF tunes a 1 MHz range, and the 
crystal converter has 30 positions.  A fairly complicated mechanical 
arrangement of gears and cams keeps the front end, crystal 1st 
conversion oscillator, and tuned IF in sync.

The first radio in the family was the 75A in 1946.  This was 
ham-bands-only, and is mechanically a lot simpler than its successor, 
the general-coverage 51J1 in 1949.  The R-390 appears in 1950, and is a 
much more expensive elaboration on the basic theme.  These were the 
descendants of the WWII AN/ARR-15 that pioneered many of the basic 
techniques.

Al

On 5/28/2012 3:56 AM, Raymond Cote wrote:
> The mil list has been talkin lately about the R388 and 51J3 equipment.  This brings to mind the thought of the evolution of these great receivers.   When was the first designe, what was the first one?  51j1???   Was there units before the J series?  What are the capabilities of the various lineage?  from the 51H, 51J, 51S R388, R389, R390 390A 391 and so forth?   Does anyone have all this in writing or does it have to be compiled, perhaps on these lists?
>
> thanks all 		 	   		
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-- 
Al Klase - N3FRQ
Jersey City, NJ
http://www.skywaves.ar88.net/