[Boatanchors] transistor help needed

J. Forster jfor at QUIK.COM
Fri Sep 4 22:47:44 EDT 2009

There is an interesting story behind the CK722.

In the very early days of transistors, they were totally unknown by
hobbiests and hams and were $$$. Norm Krim at Raytheon, the same guy who
was responsible for development of the sub-mini tubes used in hearing aids
before WW II and later made the Proximity Fuze possible, was working on
transistorized hearing aids. The yeild for hearing aid use sucked, so Norm
came up with the idea of repackaging the 'duds' and selling them to
experimenters. The blue case CK722s have a tiny transistor inside the
larger blue case.

BTW, Norm later became predident of Radio Shack and eventually sold it to

Norm is now the Raytheon Historian.



> Wow... CK722....  I have one of those in my collection.
> Went to find it and found it is silver like a crystal case.
> This one has one lead farther from the other two.
> I didn't test mine, but the fartherest one should be the collector. the
one on the other end was the emitter and the center one was the base. Or
  E,B, space C
> I also have some of the old sockets for them and a few other old
germanium transistors.
> Bob
> Sandy wrote:
>> Jesus!  I built a ouple of the old Kraft receivers a jillion years ago!
>> I couldn't be sure but I thought the red line identified the collector
leads.  I see the assembly instructions confirm this.
>> I remember the transistors were in a cylyndrical package with a round
>> top.  Seems like they were Philco transistors.
>> Didn't the old "blue metal cased" Raytheon CK722's also use a red dot
to indicate the collector as well?  The CK-722's case went from black
>> eventually to a blue painted aluminium case.  There wasn't any
>> "standard"
>> TO-5 type package in those days!
>> 73,
>> Sandy W5TVW
>> ----- Original Message -----
>> From: "Pete Lancashire" <pete at petelancashire.com>
>> To: "WØQFC" <erastber at tampabay.rr.com>
>> Cc: <boatanchors at mailman.qth.net>; <flboatanchors at yahoogroups.com>;
"BOATANCHORS at LISTSERV.TEMPE.GOV" <boatanchors at lists.tempe.gov>;
<carshamradio at googlegroups.com>
>> Sent: Friday, September 04, 2009 4:05 PM
>> Subject: Re: [Boatanchors] transistor help needed
>> a real quick google search came up with this
>> http://www.e-radiocontrol.com.ar/downloads/vintage/rxtxpulso/Single%20Channel%20Rx%2026-28%20MC.pdf
>> check near bottom of pg 5
>> -pete
>>> My transistor manual shows the base diagram of a 2N224 as having a small
>>> tab near the emitter lead; clockwise the base is next and then the
>>> The (really) OLD 2N224's I have do not have a tab, only a small red line
>>> on the side and I think this red line is marking the collector, but that
>>> is where I am not sure.
>>> Was (is) there a conventional marking system for these old transistors?
>>> Any help/ideas will be greatly appreciated!
>>> TIA es 73
>>> Gene, WØQFC
>>> Spring Hill FL

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