[ARC5] 6K8 or 12K8?

[Henry Mei'l's]

Les,

Why not just apply increasing voltage to the mystery 6/12-K8 from a variable 
supply, starting at 6V
(stopping at 12V!), and observe mA?  But now you know, anyway.
How do you guys (mates, blokes)--down under-- keep from falling off the 
planet? Sticky shoes or magnets?
Or do you just hang on for dear life.
Never mind me, nobody else does, either.

Henry
oz3a

----- Original Message ----- 
From: "Leslie Smith" <vk2bcu at operamail.com>
To: "ARC-5 List" <arc5 at mailman.qth.net>
Sent: Saturday, April 16, 2011 6:19 AM
Subject: [ARC5] 6K8 or 12K8?


> Dear list,
> Recently I put a valve marked as KEN-RAD 12K8 in series with a 12SJ7 (or
> VT13x equivalent) and measured the voltage at the junction of the
> heaters at 20 volts.  The "mystery" xK8 heater was on the "hot" side of
> the 24V supply.
>
> The question:  Did I have a faulty 12K8 or a 6K8 labelled as a 12K8?
>
> Robert Downs suggested a test to answer the Q.  Connect the heater to a
> 6V supply and measure the current drawn.
>
> Observation:  At 6 volts the "suspect" toob draws 300mA.
> Second observation:  A second "toob" marked 12K8 drew 150mA, the correct
> value according to the datasheet.
>
> I guess that observation answers the original question.
> An errant 6K8 jumped into the 12K8 bin before the labelling machine.
>
>
> Les
>
>
>
> -- 
>  Leslie Smith
>  vk2bcu at operamail.com
>
> -- 
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