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 Post subject: Re: True emission?
PostPosted: Mar Tue 31, 2020 11:46 pm 
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I have read many books on tube theory front to back, I know how they operate. Some of the old Navy tube and radio books I read put it into perspective for me better than anything else I read, and I am not implying to remove the cathode from a tube's circuit in order for it to work - although it may have sounded that way. I had a basic shop setup down here in the basement at one point during my learning curve, it creeps up on you. I eventually could align Fisher receivers with the setup. I am not an electrical engineer, and only got into this as a hobby beginning at age 45, could not tell you what a sine wave was before that, but wanted to know what the techs were speaking of, so it is just a hobby for me. Got rid of all my stuff about 10 years ago for various reasons, but kept my Knight tube tester, and lately restored my old Fender, rolling tubes, testing them and such, started thinking about purchasing a mutual conductance tester because of difference in tube sounds, but reading more, studying more I was hooked into this spiraling mind absorbing thing again, which led me to start asking questions again, and what better place than to hit you heavyweights, that's what it's all about. A further possible test of tubes over and beyond what is currently available with the old testers is what hit my mind. The post title should have been true emission testing.


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 Post subject: Re: True emission?
PostPosted: Apr Wed 01, 2020 12:54 am 
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Looks like you want a tube tester that can determine what a tube will sound like. It hasn't been invented yet.

DM


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 Post subject: Re: True emission?
PostPosted: Apr Wed 01, 2020 1:06 am 
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Probably sure that the Vt-1000 is a great tool, but wonder if it only employs all the tests that were evolved up to that point, could it detect the nuances I imagine, I don't know. There's something else going on in there to be discovered, finely feathered/extracted grids perhaps or something of that nature, we are dealing with old stuff, who knows. No, it has yet to be invented, or so it seems.


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 Post subject: Re: True emission?
PostPosted: Apr Wed 01, 2020 1:29 am 
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I am still unable to grasp what problem you are trying to solve. One thing you should consider is to answer directly various questions that have been posed. In that context, please do not edit your posts to delete something that has been questioned---that makes the thread much harder to follow.

To paraphrase some of my earlier questions: To understand what you are trying to do, we would need to relate it to the established parameters for typical vacuum tubes--including such things a Gm, plate resistance, and inter-electrode capacitance.

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"Even if you don't understand Ohm's Law, you are still required to obey it."


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 Post subject: Re: True emission?
PostPosted: Apr Wed 01, 2020 1:59 am 
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It is because as I read my posts it does sound idiotic, I am speaking in circles, perhaps, but considering my son can hear the difference in identical tested tubes with his better hearing, and he says that one is better (subjectively speaking), or just plain 'different', what tests could be developed? I just say to myself, save your money, a mutual conductance tester won't show this, but if someone finds it, a new grading system of tubes would follow, and what a can of worms that would open. It is probably too deep for anyone to sort out, best left to history of the tube itself.


Last edited by Brobertson on Apr Wed 01, 2020 3:27 am, edited 1 time in total.

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 Post subject: Re: True emission?
PostPosted: Apr Wed 01, 2020 2:44 am 
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Location: Powell River BC Canada
Brobertson wrote:
Probably sure that the Vt-1000 is a great tool, but wonder if it only employs all the tests that were evolved up to that point, could it detect the nuances I imagine, I don't know. There's something else going on in there to be discovered, finely feathered/extracted grids perhaps or something of that nature, we are dealing with old stuff, who knows. No, it has yet to be invented, or so it seems.


Vacuum tubes ceased being manufactured, (of the type the 6C4), long ago.
While they were an important part of the economy, and defence apparatus, every
part, and source material, was supplied adhering to standards.

These standards were published, and upgraded to reflect the best ways to make tubes.

You can find these if you want.

Here is such a test. Cathode Interface Impedance.

Most important things about tubes are in tube manuals.

Who would immediately care about these tests ?

Consider a TV set. All of a sudden TV repairmen start noticing
that one brand of a certain tube doesn't work properly in
a colour TV set. The grousing rises. ( without the internet ! )

And the tube maker knows precisely what process is causing it.

Page 1281 (Radiotron Designer's Handbook, (on line), will
give insight into a typical problem.

Page 1282 will provide a clue into why some old radios sets
needed 'Mallory Cells' .

Delving into (ancient) thermionics is ........ !
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de
VE7ASO VE7ZSO
Amateur Radio Literacy Club. May we help you read better.
Steve Dow
ve7aso@rac.ca


Last edited by radiotechnician on Apr Wed 01, 2020 3:11 am, edited 1 time in total.

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 Post subject: Re: True emission?
PostPosted: Apr Wed 01, 2020 2:59 am 
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Whoa, never read this one, was not far off in my hypothesis, they knew what they were dealing with, it all comes down to these materials and curing I suppose, you dig deep, I need to get these writings, they were not dealing with 'hole' theory, but in a way they were.


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 Post subject: Re: True emission?
PostPosted: Apr Wed 01, 2020 3:15 am 
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Joined: Sep Thu 23, 2010 6:37 am
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Location: Powell River BC Canada
No, you dig deep. You showed us the mountain. Climb it.

I don't use google. :D

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de
VE7ASO VE7ZSO
Amateur Radio Literacy Club. May we help you read better.
Steve Dow
ve7aso@rac.ca


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 Post subject: Re: True emission?
PostPosted: Apr Wed 01, 2020 3:31 am 
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Joined: Nov Wed 30, 2016 7:35 pm
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Location: Sunbury, Ohio 43074
.......this is not going to end well .... I've got a hole theory of my own. :-)

I said I was done with this thread, but allow me to leave one last, and hopefully useful, tidbit .....

Brobertson, it may be helpful to apply the following analogy. As a former television broadcast engineer, we would painstakingly perform color setup of each camera on a shoot (sometimes up to 20 cameras) using a color bar generator, a color test chart, and special lighting. The color bar generator was just called "bars" ..... I had the opportunity to train many video techs over the years, and I was especially good at camera setup since my eyeballs were just ... tuned I suppose one could say. I could usually tell at a glance that 'the blue gamma is off' or a white clip issue or whatever .. anyway...

BUT..... any time one of my students, or even other seasoned video operators, would complain that "I can't get the bars to look right" ... or that once the test patterns were removed and the camera was pointed at the football field, they would comment that they now had to "paint" the camera to look right.

My answer was always the same .... "we don't televise bars" .... meaning of course, that all the test patterns in the world are not better than your eyeballs. The test patterns are just to get every camera in "the same ballpark" so to speak, or for troubleshooting. Fine tuning by eye on an actual subject was always needed.

THE SAME is true of tubes, and your ears. And for that matter, speakers, and room acoustics as well.

Hope that helps.

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 Post subject: Re: True emission?
PostPosted: Apr Wed 01, 2020 11:00 pm 
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Barry, yes it does help, I see your point. Radiotechnician, I was not implying for you to dig deep, I meant you dug deeper to give me more knowledge, or a place to begin to search, It all helps. I found one ATSM site, but yet to find the tubes section that gets into this type of thing.


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 Post subject: Re: True emission?
PostPosted: Apr Thu 02, 2020 12:52 am 
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Brobertson wrote:
Barry, yes it does help, I see your point. Radiotechnician, I was not implying for you to dig deep, I meant you dug deeper to give me more knowledge, or a place to begin to search, It all helps. I found one ATSM site, but yet to find the tubes section that gets into this type of thing.

Suggestion: Put your future questions in terms of the established science, technology, and parameters for vacuum tubes. Many of us will not be able to help you if we are not speaking the same language.

To help this process, tell us if you know the definition of transconductance, and what afftects it.

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"Even if you don't understand Ohm's Law, you are still required to obey it."


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 Post subject: Re: True emission?
PostPosted: Apr Thu 02, 2020 3:38 am 
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One thing that everyone in this thread has been ignoring is that vacuum tubes don't work by themselves; they have to be part of a circuit. And they interact with that circuit. So even if you do find a test that picks out the "good" tubes for your device, that test may very well be worthless to anyone else who is using a different device. There are many threads here on ARF about someone finding a tube that won't work right in whatever they are working on yet it is fine in some other piece. The final application is the only valid test.

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 Post subject: Re: True emission?
PostPosted: Apr Thu 02, 2020 6:54 pm 
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Joined: Sep Thu 23, 2010 6:37 am
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Location: Powell River BC Canada
Examining most all old tube testers it seems that all are tied into the cathode of the tube circuit wise, even the Hickok patented circuit. It would also seem that true emission comes only from the electron cloud which is constantly replenished by the cathode setup within the tube, so then it stands to reason that that a true emission test should only be derived from the plate and control grids which tests only the pull from the cloud, totally isolating the cathode setup. Is this the failure in the old testers?

Getting back to the OT:

The Hickok circuit tested tubes at (60 Hz) or whatever frequency the tester was powered by.
Other testers used oscillators to provide a signal that was independent of the power line
frequency.

The concept of cathode interface impedance has little to do with how a tube
performed, but rather was a test of a (among many others) the materials and
methods used in the manufacturing chain.

Aside, it may be noted that in 1955 vacuum tube were used by the hundreds as
logic elements in computers. So to have one fail casting an error, was vexing.
The only other tubes under scrutiny were deployed in underseas cable
repeaters.

So to get something useful that can be done easily, the reference to the ASTM
method posted a few replies back, might be better used with this one
; ASTM designation F-300- 55 T- Tentative Method of Test for- Interface
Impedance Characteristics Of Vacuum Tube Cathodes.

It may be found on page 1563 of 1955 ASTM STANDARDS, PART 6.

That entry has the circuits needed to build Methods A, B, and C.

Other expensive test gear (in 1955) was needed.

In 2020, most on this forum would have great trouble getting this low cost E-bay stuff
past the wife, annoyed at the mounting junk pile that the hobby causes.

Bottom line is, your tube may be adding the following range of RC networks
in series with the cathodes, as they age or when they are new:

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Back to the OT. Think about an often heard comment : Tested differently
on my other tester.

_________________
de
VE7ASO VE7ZSO
Amateur Radio Literacy Club. May we help you read better.
Steve Dow
ve7aso@rac.ca


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 Post subject: Re: True emission?
PostPosted: Apr Thu 02, 2020 11:42 pm 
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Joined: Mar Tue 17, 2020 11:03 pm
Posts: 69
Read though John Harper's tube web pages, and have seen/studied others which are similar found throughout the web. I relate these back to the basic things I read in some of the Navy books. Some of it agrees, some does not. I don't have a vault of books on the subject like some. It will take me quite some time to go through these, but Maxwell's diode tube equations on this are interesting, the work and emission of metals and coatings, grid spacing's and shapes. they were basis for the further study of it, and the detailed experiments they went into, (some genius people). I find many disagreements of nature electron release and passage, usage, buildup, current at the cathode vs plate, you name it. Put in the circuit, yep, more and more sense.


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 Post subject: Re: True emission?
PostPosted: Apr Fri 03, 2020 12:49 am 
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Joined: Mar Tue 17, 2020 11:03 pm
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Are these standards online somewhere? 1955 ASTM STANDARDS


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 Post subject: Re: True emission?
PostPosted: Apr Fri 03, 2020 8:21 am 
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Joined: Sep Thu 23, 2010 6:37 am
Posts: 12437
Location: Powell River BC Canada
A librarian could tell you how to access the material.

For those wanting to experiment Test method C is shown. It requires
very little equipment.

But, it requires a lot of thought, and as said previously reading on
vacuum tube theory.

The tube collectors people have wound down, so many of those voices
aren't available.

If anyone builds this experiment, it will good to hear from them.

Some time ago an OT I posted concerned perveance and
some reference data may be useful in reading the cathode
current density material.

The capacitor in series with the vacuum tube voltmeter is there
because the first of these had a tube with a gridcap as a probe.
For DC , the tube cap was the test probe. For AC, a capacitor
and a grid leak was attached. (my opinion)

Another note, concerning Russian and other retro imports.

Why these tubes have an excellence lies in the technical testing
of materials available today, not dreamt of by the scientists
in the tube maker's plants 75 years ago.
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_________________
de
VE7ASO VE7ZSO
Amateur Radio Literacy Club. May we help you read better.
Steve Dow
ve7aso@rac.ca
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 Post subject: Re: True emission?
PostPosted: Apr Sat 04, 2020 1:09 am 
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Joined: Mar Tue 17, 2020 11:03 pm
Posts: 69
I have some Russian 5881's and fake labeled Russian 6v6's (actuallly 6l6's) that I occasionally run my Deluxe, I know should not, but the sound is awesome, they were from the late 80's I believe. The heater draw does not allow for a long play as it was designed for 6v6's - although the Schumacher transformers handle it well. The 5881's are my favorite.


Last edited by Brobertson on Apr Sat 04, 2020 10:57 pm, edited 1 time in total.

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 Post subject: Re: True emission?
PostPosted: Apr Sat 04, 2020 1:58 am 
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Joined: Mar Tue 17, 2020 11:03 pm
Posts: 69
Very interesting, the inductor and cap caught my eye first, to smooth out the results of indication, really is another way of examining a tube.


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 Post subject: Re: True emission?
PostPosted: Apr Sun 05, 2020 1:06 am 
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Joined: Mar Tue 17, 2020 11:03 pm
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. .


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 Post subject: Re: True emission?
PostPosted: Apr Sun 12, 2020 1:28 am 
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..


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