[Milsurplus] More Problems with the "VHF Primary" Myth:

[Bob Camp]

Hi

That paper is an interesting, but far from complete study of the  
crystal situation in WWII.

Bob


On Jul 18, 2008, at 3:55 PM, David Stinson wrote:

> The operational problems with WWII aircraft VHF sets lasted longer  
> than has generally been accepted,
> again proving that aircraft VHF during the war was "not ready for  
> prime time"
> and in no shape to "replace" any system during the conflict. The  
> "crystal shortage" issue, which dogged the first half of the war,
> was replaced by the "crystal aging" issue, which resulted in drift  
> and activity failure.  These problems with supplying
> the Air Corps with good VHF crystals continued past the end of the  
> war.
> From:
> IEEE Proceedings of the 35th Annual
> Frequency Control Symposium, pp. 3-12, 1981
> "A HISTORY OF THE QUARTZ CRYSTAL INDUSTRY IN THE USA"
>
> "...
> The Ageing Problem
> By the middle of 1943 the task of setting up an industry was  
> complete and crystal units were being produced in numbers adequate  
> to meet the demand. It was then that the second, and even more  
> serious crisis confronted the crystal program. Reports began to  
> filter in of extensive crystal failures both in service
> and in depot storage. The first responses to these reports ranged  
> between indifference and disbelief.  However, the reports became  
> more persistent and the Signal Corps Engineering Laboratories (SCEL)  
> at Fort Monmouth were requested to investigate the situation.
> The progress was slow because the problem was treated as an academic  
> question rather than a matter of the utmost urgency. Late in 1943 a  
> telegram was received at OCSIGO which changed the situation. It read  
> as follows:
>
> COMMUNICATIONS EIGHTH AIR FORCE BASED IN BRITAIN BROKEN DOWN LACK OF  
> CRYSTALS FIND CAUSE CURE SAME EAKER
>
> ... tests quickly confirmed the field reports. All crystal units  
> failed within a few days or at most a week or two...
> the ageing syndrome (was) characterized by loss of activity
> and increased frequency. Many theories were advanced to explain the  
> phenomenon and these had to be checked out experimentally. Meanwhile  
> the manufacturers were producing crystal units at
> the rate of a million per month; nearly all of which were destined  
> to be useless....
> The problem of ageing was especially severe in the CR-1 unit used by  
> the Air Force ...
>
> Consequently a Conference of all Crystal Manufacturers was called on  
> July 11-12, 1944....
> The problem was explained in detail and the proposed remedy was  
> presented.... Ironically, the ageing problem might have been avoided  
> had better communication existed. The phenomenon of ageing had been  
> noted as early as October 1940 at RCA...
> At home teams of GI's and civilians were trained to examine depot  
> stocks of crystal units and to select out useable units which were  
> often flown immediately to a war theatre. Later some attempts were  
> made to salvage the defective units and at least one company, The  
> Hudson American Co., was commissioned to do so. However most of the  
> units were enclosed in phenolic plastic holders and many others  
> contained brass contacts, both of which were considered  
> unsatisfactory,
> leaving little besides the quartz blank to be salvaged. It soon  
> proved to be uneconomical to salvage the units and ultimately  
> millions of the unetched units were destroyed...."
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