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" <[email protected]>
To: "Discussion of precise time and frequency measurement"
<[email protected]>
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: [email protected] [mailto:[email protected]] 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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