Building the uTracer

What people are working on at the moment
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Paul Barker
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#121

Post by Paul Barker »

pre65 wrote:I hope it is repairable Paul.

Otherwise we shall have to have a whip round for you to get the newest version. :)
Yay :D :D :D

I got it, use CV57's in place of the MJE350's! Bring it on!

We get a professor to so kindly make us a solid state piece of technical kit we haven't got a clue about, and we treat it like it's a valve.
"Two things are infinite, the universe and human stupidity, and I am not yet completely sure about the universe." – Albert Einstein
JamesD
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#122

Post by JamesD »

5A anode current pulse, 11KV max anode voltage but only 15W anode dissipation

I guess that tells the story that it has ultra fast pulse capability! That and the -800V for cutoff suggest the currents going to scream skywards at every chance it gets :cry:

Its so easy to be wise afterwards - feel for you Paul... that was a real beast to get caught with!

On the subject of blowing up test kit - I've blown up an HP 4004 volt meter this afternoon...

I think its just a duff/end of life electrolytic - sure smells like one...

J
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#123

Post by jack »

As a starting point, I look at the high side anode switch - the MJE350, T17, 500mA max - may well have exited the building.

It does have current protection, as you surmised, but that may have failed too...

Another possible failure mode would be D13, which whilst it can take decent non-repetitive pulse, would probably die quickly under these conditions.

If the uTracer is still talking to your PC, then the PIC is likely OK, and that's a good start.
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Paul Barker
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#124

Post by Paul Barker »

Thanks Nick.

Ronald has given me a series of tests to do and report back to him. I am cooking now and have to go out for the evening also, tomorrow is a family day out.

As Ed says Oh waily waily. Not sure I spelled it correctly though.
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Paul Barker
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#125

Post by Paul Barker »

nickds1 wrote: If the uTracer is still talking to your PC, then the PIC is likely OK, and that's a good start.
Phew!

Image

this is a test of the screen supply on a 340 ohm resistor.

Correct behaviour most of the way then after compliance error went haywire.

anode trace shows it measures very wrong for the resistor value by a factor of 5 at least.
"Two things are infinite, the universe and human stupidity, and I am not yet completely sure about the universe." – Albert Einstein
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Paul Barker
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#126

Post by Paul Barker »

"A person who never made a mistake never tried anything new."
Albert Einstein
"Two things are infinite, the universe and human stupidity, and I am not yet completely sure about the universe." – Albert Einstein
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#127

Post by Paul Barker »

The "what has Paul done" head scratching is ongoing at Lab Ronald. Meanwhile I am sending him traces.

Ronald will be doing a write up of the specific situation, and testing the transistors which are damaged.

He is sending the necessary, but because I am an experimenter at heart and I had an MJE350 to hand I changed that alone. Did some tests and sent the results to Ronald.

One or more of the other transistors is affected, but there is an improvement in behaviour with the MJE350 changed.

I have no conscerns about the CV57 when you look at the job it, I can't see this event damaging it.

IT is hard to know where to go with the CV57. It says in the only information on the Web I can find, that it has the same type of box cathodes as the KT66. Perhaps this is where the valve supplier who was trying to offload them got the thought it was an "PX25 triode connected".

Well it clearly isn't, but I would like to see what it is like. We must need considerable negative bias before we find out.

Possibly with the uTracer on -50v and the anode limited to 100v and a current limit inline with the uTracer I can begin to edge up some information gathering slowly step by step.

Maybe if I find a quiescent point without runnaway I just hook it up and have a listen. All in the fullness of time.

Just buggs me to see such a beautiful valve never tried.
"Two things are infinite, the universe and human stupidity, and I am not yet completely sure about the universe." – Albert Einstein
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pre65
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#128

Post by pre65 »

Looking on the interweb it seems several persons have tried CV57 in push pull.
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G-Popz THE easy listening connoisseur. (Philip)
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Paul Barker
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#129

Post by Paul Barker »

Let me just say something here which is really important for us to take to heart.

Look at the fantastic after sales support we get here from Ronald.

This is where we in the West need to support people of similar background to us, instead of buying everything from emerging industrial revolution nations just because with their low labour rates and government support (which gives them an unfair advantage in our country, I can give you an example, when I did Solar PV the European manufacturers told me the certain country taking over the market are given a 20% premium by their own government for exporting to Europe[to counter VAT]) they have a 20% trade advantage.

I used to study Economics. This is disaster. Outr Western Governments must address this.

But the biggest issue for me is the after care. I guarantee it will be nill in such a case is the one documented here.

Similarly I recently bought a muse spdif converter it doesn't work to return it with proof of postage would cost me more than it is worth. OK a small thing. But he who can't be trusted in a small thing should not be trusted in a big thing.

So why say this?

I was considering importing a CNC coil winder from an emerging nation.

No thanks. Changed my mind. I would own a few grands worth of door stop as soon as the substandard design and production values reap fruit.

I'll just have to get my finger out and make my own. It is meant to be the first project after the uTracer.
"Two things are infinite, the universe and human stupidity, and I am not yet completely sure about the universe." – Albert Einstein
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Paul Barker
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#130

Post by Paul Barker »

pre65 wrote:Looking on the interweb it seems several persons have tried CV57 in push pull.
Thanks Phil, will do a G:shock: gle.
"Two things are infinite, the universe and human stupidity, and I am not yet completely sure about the universe." – Albert Einstein
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Paul Barker
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#131

Post by Paul Barker »

OK I see Jerry at Crowthorne has built one.

If they are doing it PP and from what I have gleaned, most likely they operate it in class B.
"Two things are infinite, the universe and human stupidity, and I am not yet completely sure about the universe." – Albert Einstein
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#132

Post by Paul Barker »

4 TUBES NEUFS CV57 BRITISH ARMY, MOV england made ~~1940
10 to 50 watts possible ! sound like the 300B but bass are better
see those exemples :
Infos /cv57.htm
réalisation http://blogs.aol.fr/patrickgaffet/hifim ... --cv174/82
so those four tubes are guarantee .
MANY HOURS WITH A VERY GOOD MUSICALITY GARANTEE !!!


If the above is true they may not be dissimilar to PX25 once one learns how to bias them. Pull em up slowly on a variac I suppose and listen.
"Two things are infinite, the universe and human stupidity, and I am not yet completely sure about the universe." – Albert Einstein
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Paul Barker
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#133

Post by Paul Barker »

James wrote:Though I had referenced the uTracer heater circuit to the positive side of the filament, may not have though. Will check and re run during the week.

James.
Looks like my method was right.

I heat the dht's externally voltage devide to zero potential and connect this to the cathode uTracer post.

What is forbidden is using the internal heater on a dht and connecting that to the cathode connection. (which I would never consider doing) That is where the short circuit occurs which killed a whole uTracer.

"The situation is different when an external heater supply is used which is electrically floating with respect to the uTracer. In that case the cathode connection has to be connected to one of the heater connections on the tube (Fig. 23.2D). "
"Two things are infinite, the universe and human stupidity, and I am not yet completely sure about the universe." – Albert Einstein
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Paul Barker
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#134

Post by Paul Barker »

OK Ronald has trouble shooted it from across the North Sea.

You will have to await his right up.

Anyway it's mended.

So I had a chance to trace the effect of the resistor load on the screen.Fig.96

I am surprised.

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Paul Barker
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#135

Post by Paul Barker »

Can I just say what a pain in the butt it is to remove transistors from a through board two sides soldered pcb when you have installed them tight.

I prefer working inside a valve amp.
"Two things are infinite, the universe and human stupidity, and I am not yet completely sure about the universe." – Albert Einstein
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