[Boatanchors] Cathode ray tube base connections

[brianclarke01 at optusnet.com.au]

	Hello Clive,  

	I have no data on the CRT you nominate. However, as I recall, the 901
uses an octal base. I think the cathode and one of the heater leads
are commoned and one each of the deflection plates are commoned. This
is a device used in engineering labs to instruct 2nd year students in
the mysteries of CRT operation - quite apart from the originally
specified use, whatever that may have been. 

	Check for continuity between pins - that'll give you the heater
(expect pins 2 and 7 or 7 and 8); assume one of these is the cathode.
Apply say 200 Vdc with a 3 mA current limiter to each of the other
pins till you get a bloom on the screen (expect pin 3). Then apply
negative Voltage (WRT cathode) to the remaining pins till you can cut
off the bloom - that'll be the grid (possibly pin 5). I think you can
work out the rest. Is there aquadag on the outside? If so, that'll be
the HT - that then gives you an extra pin for either cathode or
deflection. 

	Remind me when I get home to look up the pin connections. 

	73 de Brian, VK2GCE.

----- Original Message -----
 From:"Ian Wilson" 
To:"CLIVE COLLINS" 
Cc:"boatanchor network" 
Sent:Sun, 21 Apr 2013 17:43:18 -0700
Subject:Re: [Boatanchors] Cathode ray tube base connections

Hi Clive,
The small number of pins means that there must be some shared
connections. If you can see any of the electrode structure you may
be able to work out what's what.

Let's see, the basic CRT has
filament(2) + cathode(1) + grid(1) + A1(1) + A2(1) + X(2) + Y(2)
This is a minimum of 10 pins if independently pinned.

To get down to 8 pins requires doing something special. If it is a
loctal base you could try the 1CP1 pinout: see, for example,
http://www.r-type.org/exhib/aar0006.htm

73, ian K3IMW

On Sun, Apr 21, 2013 at 9:50 AM, CLIVE COLLINS  wrote:

> Can anyone tell me where I might find the base connections for a
3CX1 crt
> please, its a rectangular 3" x 1" but there seems to be no record
that I
> can find of a datasheet anywhere, its got 8 pins on it and that has
baffled
> me completely
> Thanks for your help in advance.
> Clive GW3WEQ North Wales Coast, UK.
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