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Old 13th Oct 2020, 10:58 am   #21
murphyv310
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Default Re: Can you identify these early 1950's (?) TV bits ?

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Originally Posted by GrimJosef View Post
Thanks Nick, as far as I can tell the dimensions of the tube correspond to those on the MW31-16 datasheet here http://electronbin.com/sheets/030/m/MW31-16.pdf, which would make it a 12" one as you say.

It seems to pass Trevor's test. The heater current was 298mA (i.e. nominal). With a 10k series resistor and about 105V DC supply (the yellow meter reads a little low, and the 100V Zener was running rather warm) I got 4.43mA. This value took a couple of minutes to come up - it started at around 1mA - but maybe the cathode needed a bit of reviving ? At a second attempt it reached 4mA much more quickly. It was still climbing, albeit very slowly, when I took the picture. But given Adrian's comment about stripping the cathode and also the bad consequences if the Zener were to overheat and go o/c I took a quick snap and turned everything off.

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GJ
It's perfectly OK to leave it on. You see this on CRT tester meters as it runs. It's just the CRT coming back to life, the emission is just gradually improving. Should be a decent enough tube and set. No cabinet though?
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Old 13th Oct 2020, 11:05 am   #22
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Default Re: Can you identify these early 1950's (?) TV bits ?

Hi GJ that sounds good a lot better tube than mine.

I have just been testing mine using a DC buck converter and the lowest this one goes to is 150 Volts, with 6.3 Volts on the heaters and a 11K resistor in series with the grid, the best I get is 0.9 mA grid current, which gives me 140 Volts across the grid-cathode junction.

This is a very poor tube in my mind, the screen goes negative on high brightness settings, feedback lines start to appear before the image has any real contrast and a generally blurry image. So the readings do bear out Trevor's figures.

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Old 13th Oct 2020, 11:29 am   #23
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Default Re: Can you identify these early 1950's (?) TV bits ?

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... Should be a decent enough tube and set. No cabinet though?
All I have is what you can see in the pictures Trevor. A lot of the wiring inside the chassis has been snipped short. I suspect the previous owner was keeping these bits as a spares stock. No-one knows though, and he's no longer with us so we can't ask him.

I have no use for the tube and never will, I'm afraid. So I'll put it up in the For Sale thread for someone who might be able to use it, albeit with the bits and pieces downwind of the cathode and grid untestable here.

Likewise the chassis.

Cheers,

GJ
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Old 13th Oct 2020, 11:44 am   #24
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Default Re: Can you identify these early 1950's (?) TV bits ?

The tube should be snapped up quick GJ.
I'd be interested in the remnants of the Chassis if it's postable.
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Old 13th Oct 2020, 12:45 pm   #25
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Default Re: Can you identify these early 1950's (?) TV bits ?

I'll be interested in the tube. Many years ago I obtained a perfect cabinet and back for a Bush TUG24 and since then a chassis for a TV24.

The only help needed is how to mount the front controls and to obtain the brackets for the chassis ears at the back.

It does look like your chassis is from the TUG24 looking at the top rear mounts.

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Old 13th Oct 2020, 2:24 pm   #26
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Default Re: Can you identify these early 1950's (?) TV bits ?

I could do with the LOPT for my TV22, if it is any good, that is!

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Old 13th Oct 2020, 3:36 pm   #27
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Default Re: Can you identify these early 1950's (?) TV bits ?

I still feel I owe you something for those transformers you let me have when I dropped the projection screen off all those years ago Trevor ! I'm also grateful for the advice above about the tube. So the chassis is yours for the price of the postage if you want it - I'll PM you when I've got a number from Parcel2Go. Sorry if I've disappointed anyone who was hoping for a part. You could PM Trevor if you're desperate and see if he can spare it.

It does seem like there's more than one person interested in the tube. So I will do that properly and post in the For Sale thread. I'll leave it open for a few days and run a hat, so don't feel you have to sit glued to the forum waiting for the instant it comes up (probably later today).

Cheers,

GJ
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Old 13th Oct 2020, 5:14 pm   #28
murphyv310
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Default Re: Can you identify these early 1950's (?) TV bits ?

Hi.
Thanks GJ for the Chassis. Mark I'll check the LOPT and if it's OK it's yours. It's really the chassis I'm after not so much the individual components
Once it's here I'll pm you with the news.
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Old 16th Oct 2020, 1:58 pm   #29
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Default Re: Can you identify these early 1950's (?) TV bits ?

Many thanks Trevor, good to see you back on the forum.
I have not had much luck with the rewound LOPT
I now always dry them out thoroughly by passing a current through the windings for a few days.

I was quite gutted when the original LOPT failed within an hour of completing the restoration, as the picture was superb.

Mark
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