[Test-Equipment] TV-2

[Pete Lancashire]

Richard, actually you bring up something I am going to play with this coming
winter. I got the idea from adding a pair of A/D converters to my Tek 576 curve
tracer.

I've pretty much enough goodies to do what you mention. I've two or three Kepco
BOP medium and HV amplifiers.. This will allow me to easily  make a digitally
controlled HV supply and rest being pretty much common instruments.

-pete



On Fri, Jul 16, 2010 at 11:11 AM, Richard Knoppow
<dickburk at ix.netcom.com> wrote:
>
> ----- 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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