[Test-Equipment] TV-2

[Carl]

Or spend the kilobux for a Tektronix 570 vacuum tube curve tracer or get 
creative and adapt their 575 SS model.

Carl
KM1H


----- Original Message ----- 
From: "Richard Knoppow" <dickburk at ix.netcom.com>
To: "Discussion of Electronic Test Equipment" 
<test-equipment at mailman.qth.net>
Sent: Friday, July 16, 2010 2:11 PM
Subject: Re: [Test-Equipment] TV-2


>
> ----- Original Message ----- 
> From: "Pete Lancashire" <xyzzypdx at gmail.com>
> To: "Discussion of Electronic Test Equipment"
> <test-equipment at mailman.qth.net>
> Sent: Friday, July 16, 2010 10:10 AM
> Subject: Re: [Test-Equipment] TV-2
>
>
>>I submit I have been fooled .. but having a tube that has
>>its
>> characteristics accuratly known
>> as a verification I guess is like having a known resistor,
>> cap etc as
>> a check for a bridge.
>>
>> -pete
>>
>    If you _really_ want to know what a tube is doing you
> can set up a "first principles" arrangement and measure its
> characteristics. You will need a couple of power supplies,
> one for the plate and screen grid, one for filament, and
> another for bias, the latter can be batteries. All but the
> filament should be adjustable over enough range to make tube
> curves. In addition you will need a couple of voltmeters.
> Current can be measured using a voltmeter and series
> resistors. One can do this with a single voltmeter but its a
> PITA. The tube handbook will give you some idea of what the
> tube should be doing. To measure "dynamic" characteristics
> you need the above plus an oscillator which is adjustable
> for both frequency and output level and an accurate AC
> meter, preferably two. The set ups for measurements can be
> found in many places, I think the older editions of the RCA
> tube handbooks included it. They also have a very good text
> section on how tubes work and how to design tube circuits.
>      In addition to the tube you will need an appropriate
> socket. The tube socket and terminals for the supplies can
> be mounted on a wood board, the most versitile arrangement
> is simply to run short leads from each socket terminal to a
> terminal like a Fahnstock clip or binding post. An
> oscilloscope is useful but not necessary.
>     This arrangement will allow you to measure all static
> (steady state DC) characteristics, generate tube curves and,
> with the oscillator, measure AC characteristics such as
> distortion. You can determine true Gm, amplification factor,
> and impedances this way. Its somewhat time consuming but not
> difficult. I had to do this in school for one of my
> electronic labs.
>     Since there is published data on virtually all tubes
> its possible to know the "typical" characteristics and from
> those find tubes that are worn out. One can also set up to
> measure leakage shorts and gas.
>
>
> --
> Richard Knoppow
> Los Angeles
> WB6KBL
> dickburk at ix.netcom.com
>
>
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