Anyone recognise this ancient CRO? - Page 3

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Re: Anyone recognise this ancient CRO?
On 7/07/2013 5:43 PM, Phil Allison wrote:
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One of the little games in our apprentice workshop was when somebody had  
got as far as finishing the power supply and had installed the tube, was  
to distract them while a small magnet was slipped inside the umetal  
screen leaving the victim trying to work out why he couldn't get a dot  
on the screen.

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Re: Anyone recognise this ancient CRO?
I've just received a pile of new photos of the CRO. You can see them at  
http://tinyurl.com/2inchcro

Strange that it's got a mixture of old and mostly newer components in  
it. The bloke's son says he saw it working in the 1960s... maybe that's  
when it was built, also using a few waxed paper caps he had in stock?

The CRT is an RCA 902, making it look more like the CRO could be a clone  
of the RCA 151-2 which also uses a 902 tube.


Bob



Re: Anyone recognise this ancient CRO?

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That scope looks like the one described in the March 1950 edition of Radio &  
Hobbies.  It was designed by the late Derrick Williamson, with whom I had  
the privelidge to know as a friend, colleague and mentor.  A revised version  
with a linear "hard" timebase was published the following month.  The four  
octal valves is slightly at odds with the original, which had a 6SJ7 to  
drive each set of deflection plates, an 884 for the timebase, and a 6X5 for  
the HT rectifier.  An 80 supplied the EHT, making five valves.  Perhaps one  
of the valves is missing or not visible in the photo?
--  
Regards,

Chas.

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Re: Anyone recognise this ancient CRO?
On 9/07/2013 20:16 Chas wrote:
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There's a much more comprehensive set of photos in my online photo album  
now, at http://tinyurl.com/2inchcro

The valves have been identified as 2x 6J7G, 1x 80, 1x 884, 1x 902 (CRT).  
It looks as though the builder of this instrument could have adapted the  
design of the 1938 RCA 151-2 Oscillograph to use locally-available  
parts. You can see it at  
http://www.myvintagetv.com/vintage_test_equipment.htm a bit down from  
the top of the page.



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