[time-nuts] And you thought you were old

Reeves Paul Paul.Reeves at uk.thalesgroup.com
Wed Apr 21 03:15:50 EDT 2010


I did the same (a VERY long time ago...) with the OC71. Schoolboy funds
could not reach OCP71 levels. They made good phototransistors until Mullard
found out and started filling the glass encapsulations with a white
compound. Spoilsports :-)
But all you had to do was break the glass and scrape off the compound -
worked fine. I can't quite envisage doing that with a modern equivalent!

73
Paul Reeves    G8GJA

-----Original Message-----
From: Jean-Louis Oneto [mailto:Jean-Louis.Oneto at obs-azur.fr]
Sent: 20 April 2010 19:31
To: Discussion of precise time and frequency measurement
Subject: Re: [time-nuts] And you thought you were old


I used their low power variant (OC45) to make my first audio optical link 
(free air, analog f course !) using flashtorch parabola as Tx and Rx 
"antennae". The OC45 was black painted transluscend plastic. You just had to

scratch the paint to get a nice phototransitor...

----- Original Message ----- 
From: "Horst Schmidt" <horsts at iinet.net.au>
To: "Discussion of precise time and frequency measurement" 
<time-nuts at febo.com>
Sent: Tuesday, April 20, 2010 2:52 PM
Subject: Re: [time-nuts] And you thought you were old


>I still have an original booklet from raytheon : how to build a 1 
>transistor radio with a CK722.
>
> However, my very first transistor first transistor was an OC70 from Valvo 
> (German Philips). I bought it about 1956 ,I was 13 years old then in 
> Stuttgart Germany.
>
> It cost me 10.20 German Marks. A substancial sum then.   I  soldered the 
> transistor in to a socket , so the leads would not break off.
> I build many different projects with it then.
>
> Now when I see one of the old black Philips  glass encapulated 
> transistors, I get quite nostalgic.
> But this days one hardly looks at a modern transisitor anymore.
>
>
>
>
> On 21/04/2010 12:19 AM, Mike Feher wrote:
>> In fact, one of the first CK-722s that I took apart did have a smaller
>> hearing aid type transistor inside. Later CK-722s were of course built as
>> CK-722s and even later they were in black but somewhat clear epoxy 
>> cases. -
>> 73 - Mike
>>
>> Mike B. Feher, N4FS
>> 89 Arnold Blvd.
>> Howell, NJ, 07731
>> 732-886-5960
>>
>>
>>
>>
>> -----Original Message-----
>> From: time-nuts-bounces at febo.com [mailto:time-nuts-bounces at febo.com] On
>> Behalf Of J. Forster
>> Sent: Tuesday, April 20, 2010 9:57 AM
>> To: Discussion of precise time and frequency measurement
>> Subject: Re: [time-nuts] And you thought you were old
>>
>> Do you know the story of the CK722?
>>
>> In the 1950s, Raytheon was making tiny transistors for hearing aids to
>> replace the pre-WW II subminiature tubes.
>>
>> Aside: Those tubes, developed by Norm Krim, were ruggedized and used in
>> the WW II Proximity Fuzes, one of THE big inventions of WW II.
>>
>> Anyway, Raytheon was making piles of these tiny transistors, but many 
>> were
>> not making hearing aid specs. Norm got the idea of packaging them to sell
>> to hams to learn about transistors. If you open up one of the blue ones,
>> there is another tiny case inside which is the real transistor.
>>
>> BTW, Norm is still alive and well in his 90s.
>>
>> -John
>>
>> ===============
>>
> Anyone remember the CK722 transistor? As I remember they were about $7.50,
>>> a
>>> considerable sum.
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