[Tod Treganowan]

Which way should the diode's cathodes be oriented when making a solid state
recitifier adaptor for my Hickock? From the junction of the two resistors,
are the cathodes both on the resistor side (top) or facing the pins of the
socket? Or is one up and one down? I'm trying to figure it out, but I
want to be sure.

Thanks

[[email protected]]

On Apr 29, 3:46*pm, "Tod Treganowan" wrote:
Which way should the diode's cathodes be oriented when making a solid state
recitifier adaptor for my Hickock? From the junction of the two resistors,
are the cathodes *both on the resistor side (top) or facing the pins of the
socket? * Or is one up and one down? *I'm trying to figure it out, but I
want to be sure.

Work it out until you think you have it then build a test fixture and
try it out. Use a high impedance AC source. What's a high impedance AC
source? Use a series light bulb and a transformer.

Then put it in the tester.

The learning to figure it out yourself is the important thing here.

[Fred[_8_]]

"Tod Treganowan" wrote in message ...
Which way should the diode's cathodes be oriented when making a solid state recitifier adaptor for my Hickock? From the junction
of the two resistors, are the cathodes both on the resistor side (top) or facing the pins of the socket? Or is one up and one
down? I'm trying to figure it out, but I want to be sure.

Thanks

Tod,

You may have already seen this page. All you need to know to use it
is that the cathode of a SS rectifier is the end with a stripe on it. The
other end (the anode) isn't usually marked, but if it is, it has an arrow
head pointed at the line (stripe) on the cathode end.

http://www.antiqueairwaves.com/nlee/tv-3&10.html

Last time I had a teacher who's only contribution was to say, "Figure it
out," I walked out instead. I'm pretty sure I didn't miss anything. . .

Good luck,

Fred

[Tod Treganowan]

"Fred" wrote in message
...

"Tod Treganowan" wrote in message
...
Which way should the diode's cathodes be oriented when making a solid
state recitifier adaptor for my Hickock? From the junction of the two
resistors, are the cathodes both on the resistor side (top) or facing
the pins of the socket? Or is one up and one down? I'm trying to
figure it out, but I want to be sure.

Thanks

Tod,

You may have already seen this page. All you need to know to use it
is that the cathode of a SS rectifier is the end with a stripe on it. The
other end (the anode) isn't usually marked, but if it is, it has an arrow
head pointed at the line (stripe) on the cathode end.

http://www.antiqueairwaves.com/nlee/tv-3&10.html

Last time I had a teacher who's only contribution was to say, "Figure it
out," I walked out instead. I'm pretty sure I didn't miss anything. . .

Good luck,

Fred


Thanks, Fred

The cathodes both go on the resistor junction side! Now all I need are some
bases.

Tod

[[email protected]]

On Apr 30, 11:42*am, "Tod Treganowan" wrote:

The cathodes both go on the resistor junction side! Now all I need are some
bases.

Gently twist the globes off the old 83s. DO NOT BREAK THEM OUT - there
is quite a bit of mercury in an 83. Dispose of the (unbroken) globe as
you would hazardous waste. If it is already broken, you can fairly
easily remove the base from the remainder of the glass by de-soldering
the pins and tugging gently, one-by one.

I made exactly the one pictured for my 739B - it turns out that no
recalibration was necessary based on my sample tubes.

Peter Wieck
Melrose Park, PA

[Dr. Barry L. Ornitz]

wrote in message
...
Gently twist the globes off the old 83s. DO NOT BREAK THEM OUT - there
is quite a bit of mercury in an 83.

I made exactly the one pictured for my 739B - it turns out that no
recalibration was necessary based on my sample tubes.

So I take it that you do not add a Zener diode to simulate the
(relatively) constant voltage drop of the mercury rectifier. This is
around 14 to 15 volts for the 83. but is around 10 for the
Mercury 866 and 872. The Xenon 3B28 has a voltage drop of 10 volts too.


--
73, Dr. Barry L. Ornitz WA4VZQ

[[email protected]]

Having to figure these things out was how I learned and when i had
done it I remembered it. You can look at the schematic and if you know
the symbols it is obvious, but paying your dues-that is, learning how
to learn-is THE POINT.

When I got my first job at a transformer place we had an exercise
with some transformers. All the leads out were the same color. We had
a diagram of the transformer, a schematic, with the wire colors which
should have been on the part and there were roughly ten or eleven
leads. You had to put these little beads on each wire and then the
next person would verify if they were right or wrong. Keep in mind you
had those phase dots as well as the symbols. You had a beeper, a
Simpson 260, a shopbuilt audio oscillator and a 400 Hz 12 volt supply
to make it work under power. (All you needed was the beeper and the
oscillator really.) It was very frustrating at first but pretty soon
you got fast at it,"phasing out" the transformer in a minute or so.

They would work with you mostly by answering any question with
another question. Out of twelve people a couple did wash out that
day. But the ones that passed got to be really good with transformers
in terms of test. We never were allowed to wind a transformer which I
thought would be educational, but test and production were two worlds
apart. The winders were ALL female and NONE had any training or
interest in electricity or electronics per se. The techs were mostly
male, we did have a couple of "test operators" who were women from the
production side of the house that had come over. They were older gals
and they were apparently in the same status as "professional flight
engineers" with the airlines, nonpilot FE's from the shop with A&P
licenses and a lot of engine skills who crossed over back in the old
days and stayed on the grandfather basis when airlines made the FE
position the entry level one for pilot new hires. We had no young
TOs. I never found out if that was a formal policy or not at that
plant. That plant paid pretty ****tily-it was in a ****ing CONVERTED
CHINESE RESTAURANT, I can't make this up (the principals were not
Chinese) and I left in a few months.

Also, taking the 83 apart is a bad idea. Take apart a non mercury
type with the same base and use that!!!!!!!!!!

[[email protected]]

On Apr 30, 7:56*pm, "Dr. Barry L. Ornitz"
wrote:

So I take it that you do not add a Zener diode to simulate the
(relatively) constant voltage drop of the mercury rectifier. *

Good to see you back, Barry!

No, I do not when I make the drop-in substitute on a tube base. The
resistors are to simulate that drop - and on the three Hickoks I have
done this for, all have done well with it. Once (1-time) I set the
rectifiers in-line for someone who insisted on that process and
brought me the schematic to follow - so no resistor were required per
the schematic. I seem to remember that he had to have someone else add
a zener later on for the purpose you suggest.

I would not have done it that way. For the record.

Peter Wieck
Melrose Park, PA

[[email protected]]

On Apr 30, 9:42*pm, wrote:

*Also, taking the 83 apart is a bad idea. Take apart a non mercury
type with the same base and use that!!!!!!!!!!

Bret Ludwig under yet another alias?

Exactly what is wrong with removing the globe from a dud 83 tube?
Disposal is exactly the same thing - and at least the base is
recycled.

Peter Wieck
Melrose Park, PA

[[email protected]]

On May 1, 6:44*pm, Curtis Cathode wrote:

Don't bother. Your Hickok tube tester will work much better and accurate
with a real 83.

Actually, no it won't. As the 83 degrades with age, the Hickok will
require re-calibration to a weakening 83. And before it fails
entirely, it starts giving false readings on power-tubes, yet remains
just fine for small-signal tubes.

The 83 is considered a low-loss rectifier and so was chosen by Hickok
- the solid-state drop-in replacement has the virtue of not degrading
with age, nor will it give false readings once the system is properly
calibrated to it - if necessary. And, it takes considerable load off
the transformer. All good things.

Also, the SS replacement cost about $4, including the dud tube to make
the 4-pin base.

Peter Wieck
Melrose Park, PA

[Alan Douglas]

Voltage drop is 13V for the 83s I've measured, but it doesn't seem to
matter whether it's 13V or 0V, as long as it's low. So I've never seen
any need to add zeners. If anything, the extra plate voltage gives a
better test.

The resistors are only there to simulate the transformer center tap,
which is not available at the 83 socket. If you wire the diodes in
permanently, they can go directly to the center tap.

Alan

[[email protected]]

On May 1, 8:05*pm, " wrote:
On May 1, 6:44*pm, Curtis Cathode wrote:

Don't bother. Your Hickok tube tester will work much better and accurate
with a real 83.

Actually, no it won't. As the 83 degrades with age, the Hickok will
require re-calibration to a weakening 83. And before it fails
entirely, it starts giving false readings on power-tubes, yet remains
just fine for small-signal tubes.

The 83 is considered a low-loss rectifier and so was chosen by Hickok
- the solid-state drop-in replacement has the virtue of not degrading
with age, nor will it give false readings once the system is properly
calibrated to it - if necessary. And, it takes considerable load off
the transformer. All good things.

Also, the SS replacement cost about $4, including the dud tube to make
the 4-pin base.

Peter Wieck
Melrose Park, PA

In this instance you are absolutely right, there is no good reason to
fool with the original 83.

[[email protected]]

On May 6, 6:47*pm, wrote:

In this instance you are absolutely right, there is no good reason to
fool with the original 83.- Hide quoted text -

Bret:

83s fail. And they fail with startling regularity. Further to this, in
Hickoks, they are mounted horizontally. They are not rated for that
application. Hence, they tend to fail more quickly than if mounted
vertically. The solid-state replacement (at a small fraction of a new
83 in cost) will not fail, does not require anything other than
routine maintenance, once calibrated (if even necessary) and reduces
the load on the transformer.

Now, your answer could be interpreted to mean either LEAVE THE OEM 83
IN PLACE - or don't waste your time with an OEM 83. Which?

Peter Wieck
Melrose Park, PA