[R-390] TV-7/U (Square peg, round hole)

[Bob Camp]

Hi

The adapter part is fairly easy. You pick a "close" tube and wire it  
up so the pins come out in the right places. More or less, cathode to  
cathode, filaments in the right place etc.

Pretty much all testers set up the grids in a fairly predictable  
pattern. If you grab a TV-7 schematic and data for a couple of similar  
tubes, it should be fairly obvious what they are doing (hook these to  
the plate, those to the cathode, the rest to the control grid ....).  
Depending on the tester they will do things a bit differently. You  
depend on the fact that they are going to set up all pentodes the same  
way ....

Bias on the control grid is about the only major variable. Essentially  
you are measuring plate current with a fixed bias. You can go through  
a lot of math to work out what the numbers should be. The "easy" way  
is to plug in a known good tube and fiddle the bias switches until you  
get a reasonably easy to see reading ....

Bob

On Oct 27, 2007, at 9:31 PM, Richard Spargur wrote:

> Does anyone have a method for testing new tubes (does not have  
> identified
> test setup and data) on a TV-7/U?  I want to test tubes like the  
> 6LQ6 Sweep
> Tube, but it has a nine pin arrangement which is not compatible with  
> either
> a TV-7/U.  There was a fellow in JA-land, radiomann (that is how he  
> spells
> it), that built an adapter for testing tubes and a bit of a guide on  
> how to
> develop new test data, but now it is all in Japanese.  I am not  
> leterate in
> Japanese for me it might as well be in ancient Egyptian  
> Hieroglyphs.  Any
> help?
>
> Richard
> K3UI
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