[R-390] Testing tubes r392

[rbethman]

There are few that seek to collect and retain "period" pieces, other 
than a few pure collectors.

The TV-10 is just fine.  However, I'll stick with the later WE labeled 
Hickok LS-1XXXXX series.  It adjusts to the line voltage, and reads 
directly in mhos.

There is one flaw in "blasting crud" off tube elements by "heavy" 
current blasts.  The one element that may "need" this is the filament.  
This would occur in Thoriated tungsten filaments.

It would be prudent to keep this "blast" per se, down to a certain 
percentage above the normal operating curve.  The key being "current" in 
lieu of voltage.  The element will only take a certain amount of 
current,, as its resistance is essentially fixed.  Yes, there is some 
degree of variation depending on whom made the tube, but it is just like 
testing a fuse with an over current.  These aren't circuit breakers.

One blown, the method of repair becomes solely replacement.  The older 
some of the tubes are, and how much the audio crowd has latched upon 
them, determines how much this replacement is going to cost you.

Bob - N0DGN

On 8/6/2012 12:10 PM, Randy and Sherry Guttery wrote:
> I have a different opinion on this - while the TV-7 series
> is indeed a fine tester, and period "correct" for much
> military vacuum gear; it is by no means the "most" on
> several counts.  In my opinion - the TV-3B is far more
> collectible as a period piece - and certainly as competent
> as a TV-7 for most early military tube gear. With it's
> built-in Multi-meter and "hidden power cord compartment" -
> it's "coolness" factor is almost off the scale.  When it
> comes to competency - the TV-10 is (IMHO) far more useful
> than a TV-7 - as it does not require a "chart" to test a
> tube - it can be set up using a tube manual and since is
> reads directly in umhos -it's readings are directly useful
> (the TV-7 series reads in 0-120 "quality" -- requiring extra
> work to determine an actual reading). The TV-10 can also be
> used to "beam" a tube (heavy current blast - to blow crud
> off the elements and expose fresh emitter areas).
>
> Just my .02
>