[Milsurplus] TV-7 Calibration

[Richard Solomon]

You can also use a General Radio Resistor Decade Box. They can be
found every now and then at Flea Markets for short money.

73, Dick, W1KSZ


On Mon, Apr 29, 2013 at 8:41 AM, Mark J. Blair <nf6x at nf6x.net> wrote:

>
> On Apr 29, 2013, at 08:24 , Ralph Cameron <ramcam at magma.ca> wrote:
> > The cal. procedure for the TV-7 tube tester lists ZM-16U, resistor,
> decade ,TM-11-5102 as one of the needed pieces of test equipment. Are these
> available surplus anywhere or does anyone have one for sale. I expect it is
> a standard decade resistor box from 1-1Megohm but haven't seen a
> description of it.
>
> If my memory serves me correctly (don't bet any money on that!), you'll
> need the resistor box or some other way to try out fixed resistor values
> with earlier TV-7 machines. If you happen to have a later model TV-7D
> machine, then there are potentiometers for the calibration adjustments, and
> I don't think the decade resistor box is needed to calibrate them.
>
> I calibrated my TV-7D back in 1999 or so, and I couldn't get the
> adjustments to converge initially. After much head-scratching, I figured
> out that the calibration procedure was written for a VOM with 1,000 ohms
> per volt impedance, and my fancy DVM with its high impedance didn't load
> the circuits enough to make the measurements come out right. I wrote about
> this pitfall way back in the day:
>
> http://www.nf6x.net/1999/01/tv-7-tube-tester-alignment-hints/
>
> A google search for "ZM-16 decade resistor" turns up plenty of pictures,
> as well as a PDF copy of its technical manual:
>
> http://www.liberatedmanuals.com/TM-11-5102.pdf
>
> It covers 0.1 through 111,111,111 ohms.
>
>
> --
> Mark J. Blair, NF6X <nf6x at nf6x.net>
> http://www.nf6x.net/
>
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