[pure-silver] Re: Off topic, Spot meter problem

  • From: "Richard Knoppow" <dickburk@xxxxxxxxxxxxx>
  • To: <pure-silver@xxxxxxxxxxxxx>
  • Date: Tue, 20 Oct 2009 12:30:59 -0700
----- Original Message ----- From: "Jean-David Beyer" <jeandavid8@xxxxxxxxxxx> 
To: <pure-silver@xxxxxxxxxxxxx>
Sent: Tuesday, October 20, 2009 11:45 AM
Subject: [pure-silver] Re: Off topic, Spot meter problem



Tim Daneliuk wrote:

Dana H. Myers wrote:

Tim Daneliuk wrote:

 We had a saying at the Radar shop back in the
Bad Old Days, "If you can't fix it with WD-40, a hammer, and some 1N914s *** it can't be fixed." I do not recommend hammers when tuning 
a Pentax meter :)
*** A 1N914 is a type of diode very common in many kinds of radios 
    and Radars.
Back when I was in the electronics biz, radars used various versions of the 1N21 for the mixer. This was true even when 1N914s were very cheap and widely used in digital circuitry. 1N914s were about $2 a piece when they first came out. Later, one semiconductor vendor gave them to us free if we bought all our transistors from them, which we did. 


Though 1N4148s seem to be more common these days.

;-)
You have to understand that I'm not that old, I just did this Radar thing a long time ago (at the age of 5 :) Back then the 1N914s ruled.
P.S. I am, however, old enough to have done lots of service work on 
equipment employing "Vacuum FETs" (aka Pentodes) <smirk>
Actually, Lee DeForest tried to make a triode that really was an FET. The grid was a screen of wire OUTSIDE the glass envelope of a thermionic diode. While it worked, it made such a bad detector that plain diodes were used instead. He did patent it though and later, when AT&T thought to put the grid between the cathode and the plate, they ended up buying DeForest's patent for $1 million to avoid a nuisance in the courts. 

--
.~. Jean-David Beyer Registered Linux User 85642. /V\ PGP-Key: 9A2FC99A Registered Machine 241939. 
 /( )\ Shrewsbury, New Jersey    http://counter.li.org
^^-^^ 14:35:01 up 19 days, 23:34, 3 users, load average: 4.28, 4.29, 4.27
There is a pretty good article about DeForest at: http://en.wikipedia.org/wiki/Lee_De_Forest It points out that DeForest did not really understand how the triode worked. He also did not understand that a really hard vacuum was necessary. The methods of achieving the vacuum and other changes were worked out simultaneously and indepantly by Irving Langmuir of General Electric's research laboratory and Henry D. Arnold of Western Electric's lab (which eventually became Bell Telephone Laboratories). General Electric and AT&T formed RCA in 1919 to act as a sort of legalized monopoly holder of important radio patents including vacuum tube patents. This combination bought out the American Marconi Company and perhaps twenty five small companies that had patents valuable to the radio industry. I am not sure of DeForest's position, my understanding is that he lose an interference suit against GE about the vacuum tube when he was not able to explain its operation to the court. GE or RCA may well have bought him out but he also held the patent for the regenerative circuit and that may have been involved. This patent, BTW, was involved in one of the longest priority suits on record. The other claimed inventor was Edwin Armstrong and the court case went on for a dozen years. RCA's early history is complex. Originally intended to allow GE and others to be able to manufacture equipment mainly for the U.S.Navy and to provide communication via wireless overseas and to ships RCA became involved with broadcasting almost right away and the pioneer broadcaster the Westinghouse Electric and Manufacturing Co. became a partner. For many years tubes sold under the RCA, GE, and Westinghouse brands (as well as some others) could come from the very same factories the only difference being the markings. 

--
Richard Knoppow
Los Angeles, CA, USA
dickburk@xxxxxxxxxxxxx 
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