TV-7 Tube Tester Calibration (1) Tools You Need to Get:

1) TS/352 Multimeter ( US Military Circuit Tester ):
This multimeter is easily available here in Japan and is a little more expensive than easy-to-buy domestic multimeters,
but the merit of this circuit tester is that it can read 0.5 volts DC, and that in addition to the strong shock and water-proof structure
the meter itself is very large, As a result, it is very easy to read meter indications. I always use this multimeter when I check up plate,
screen, and bias voltages.

2) A Decade Resistor:( Resistor Box ):
You can come by this kind of device anywhere in the world, and is not expensive. This device is composed of 4 - 5 rotary switches
and resistors of comparatively strict tolerance connected in series to make up one resistor value. We in Japan call this kind of device
in an electronic laboratory "A Resistor Box." 1 got one, Heathkit RD-1, produced by Heathkit Co. at Ebay Auction site for about
$25.00 US Dollars. The resistor values vary from 10 ohm to 100k ohm, 10-19 ohm, 20-100 ohm, 100- 1000 ohm, 1000-10k ohm,
and 10k -100k ohm. When you want an appropriate resistor value for modify shunt resistors for TV-7/U, TV-7C/U or TV-7A/U tube
tester, you need this kind of device. If you are calibrating TV/7B/U, or TV-7D/U tube tester, you won't need this device at all simply
because variable resistors are used for shunt modification inside.

3) A Digital Multimeter:
For very exact measurement of filament voltages, a digital multimeter is a very convenient tool. No expensive one is necessary for
this purpose, though.

4) Tube Socket Adapter Kit (MX-1258/U):
One of the tube socket adapters,U-102/U , is designated to be used for tube tester calibration, you simply insert this adapter into
the octal socket, then the measurement of each voltage through the octal basing socket becomes far easier than without, because
the pin number is clearly written and even the metal touch points are provided for circuit tester measurements. You can check up the
voltages pf plate,screen, bias and filament with a lot more ease, yet if you find it difficult to purchase this adapter you can do without
it, of course. Before I come by this adapter, I used to make use of tester leads, and insert them into each socket hole, and I was able
to do just the same job.

5) A Variac or Slidac ( called so in Japan ):
A variac is necessary to produce 50V AC volatage for conducting a signal voltage inspection; As we need to vary voltage from
48-49V AC to 50-55V AC, a variac is something we need to purchase at any cost. No big variac with large current capability is
necessary. I believe 1 - 2 A variac is just okay for calibrating TV-7 tube testers.

6) Daniel Nelson's "Standard( Reference) Tubes":
As I mentioned in other portions of this webpages, the read-out values of each tube tester meter are not always to be trusted even
after complete calibration. Mr. Daniel J Nelson, TV-7 expert living in Arizona, USA, says that there is approximately plus/minus 6
percent reading difference on each tube tester. On one TV-7 tube tester reading is such, and on another reading is such --
You will be at a loss which tube tester reading is correct or trustworthy. The final means possible to work out all this problem is
to get Mr. Nelson's "Standard (Reference) Tubes". He is the person we call the TV-7 Doc of the United States. You can get his advice on this matter by writing to him. Send your email message to Mr. Daniel J Nelson.

7) US Military Maintenance and Repair Manual:
US Military Maintenance Manual is our Bible for TV-7 tube tester repair or calibration without doubt. I always read it through and
through whenever I come across any problem. You can get a copy of this manual by getting touch with Mr.Roger Engle, living in
Florida, USA. and his email address is ziggy7@bellsouth.net  He will sell his copy at a reasonable price. There are pages devoted to
calibration and tips for troubleshooting,and they are of great help in pin-pointing trouble spots and repairingthem. But I remind you,
they do not mention everything about tube tester repair techniques -- like every special field skill, expertise should be learned and
acquired for yourself, say, by trial and error, all you need is a simple knowledge of OHM's LAW and some experience inhandling vacuum
tube radios or audio amplifiers, and how to read the schematic diagrams of TV-7 tube testers, but you need some years' experience in
understanding the principle and/or fundamental handling methods of TV-7 tube testes. Those who were charmed by their cosmetic
beauty or the functions of them will continue to poss one or purchase one TV-7 tube tester after another, and will never cease to
love them.

To be continued;
Philip/JA3KEV
January 14th,2003