The Beast

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The Beast

Postby Harry Dalek » Thu Mar 25, 2021 9:19 pm

This one has come about due to my 60s oscilloscope BWD 421A mains transformer kicking the bucket and i am unlikely to find a replacement so pretty much junk and now spare parts to me ..nothing lasts forever as they say .
IMG_0055.JPG

So been studying up on the GEC 1025H cathode ray tube,its the same tube as the 1000 H used in the D 43 Scope pdf posted apart from a different phosphor
its also equivalents are CV8299 SE4D31 what phosphor they use i don't know mines Green as in the phosphor PDF below .
This double gun cathode ray tube with spiral helix PDA was made by GEC-MOV. Also used in the Telequipment D43 scopes.
The tube 1074H is the same tube with different phosphor.
GEC CRT numbering system:
first two digits= screen size in mm =10
next two= screen type. 24 or 74 or 25
24= short, green, as P31 or GH.
74= as 24 with Aluminised screen (by adding 50 to phosphor type)
the 25 screen is short, green-yellow, as P2 or GL.
Letter indicates tube type/characteristic. H = two guns, with PDA.

The CRT is of interest dual deflection as it will push me to learn how to tame this Beast thus the name :wink:
Rather interesting Tube with 2 guns 2 sets of deflection plates for the Y The X i think it uses one half for either gun or perhaps you could use both for one gun ,unless i am misreading the D43 scope schematic .
So 2 EHT supplies also needed for this and some other supplies as shown in the D43 Schematic and data .
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The Mu metal screen was rather grubby so cleaned that and gave if a paint job for the New Project ,i also had a case large enough to reuse for this
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Now the Tube needs to be mounted as its not safe with these power supplies ,so this step is where i am up to took a little while to work out the best way with the case i have .
The 2 silver panels and hidden door panel will hold the controls ,still need to cover holes back of case .
This CRT is all experimental depending on how well i can control it will depend on how it ends up ,what i would like it to do is similar 2 the 240 line 2 hz frame rate test on the Devil monitor but horizontal scanning so something like 120 180 240 line frame rate select ..using low frame rate i can use the audio bandwidth of my PC to display higher quality which would be lost trying a higher frame rate also the phosphor is a little longer so more suited to a low frame rate ..any case if it gets to this stage i will play around here.
I forgot if i can also do a dual display i will do something similar to the Binocular monitor but unlike having a sperate CRT for the scope and have a scope display below the video image on the same crt ,well want and can do depends first up if i can light this Beast .
OH well Fingers crossed one hand behind my back and here we go again ...
Attachments
1074H_D43_crt-wm.pdf
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Telequipment--D43--service--ID9899.pdf
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CRT screen phosphors-wm.pdf
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The electromagnetic spectrum has no theoretical limit at either end. If all the mass/energy in the Universe is considered a 'limit', then that would be the only real theoretical limit to the maximum frequency attainable.
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Re: The Beast

Postby Harry Dalek » Fri Mar 26, 2021 6:29 pm

Today CRT mounted fixed to case ,back panel blocked and 240 socket + panel switch added ..that's out of the way safe to start wiring now .
Attachments
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The electromagnetic spectrum has no theoretical limit at either end. If all the mass/energy in the Universe is considered a 'limit', then that would be the only real theoretical limit to the maximum frequency attainable.
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Re: The Beast

Postby Harry Dalek » Sun Mar 28, 2021 3:48 pm

Well the power supply is now mains connected So i have the HV negative and some of the high positive , dual 12 volt supply for the circuits ,What i had been thinking about was how to do the under 3kv EHT was going to use a cheap Chinese HV module with a lm317 to it to adjust the output this worked fine for the magnetically deflected CRT projects i have done ..
Looking at the old scopes old caps at its once EHT supply they are all rated at 3KV so we are looking at a 2 or under 3kv supply i will just make that via the mains transformer as i am doing for the Negative and lower positive supply in the few hundreds ,easy enough if you take care .

I could of hooked the heater up today but will leave that till i work on the the CRT plug i was more interested in working out how to mount the boards so i had enough space , so if every thing works out i can stick in another board or 2 ,lots of room in the case but not so easy to place every thing and mount if i go flat so going vertical easier to get to every thing and gives me lots of board mounting room .
Use what's laying around best way you can i say ...free that way !
Attachments
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The electromagnetic spectrum has no theoretical limit at either end. If all the mass/energy in the Universe is considered a 'limit', then that would be the only real theoretical limit to the maximum frequency attainable.
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Re: The Beast

Postby Harry Dalek » Thu Apr 01, 2021 6:59 pm

Bit more work today but bit flat out till next week due to Easter .
I had another thought about the EHT needed since this is a little experimental i may be a bit limited using the mains transformer for this which i am already doing for the high negative positives in the hundreds of volts and low dual circuit supplies , So i think i will try my ZVS flyback with a variable low voltage supply to it can run on 10 to 40 volts have to do some testing again but last test i got a touch over 1.200 volts to high 12.050 volts ..i will have to set it so its controllable from low 1Kv to 4kv keep it safe for the CRT .
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Mounted but need to add the variable dc supply this will adjust 1 to 4 Kv
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Next i needed a place to fix the the CRT connections to terminals easy to work out what goes where .

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So still a few things to do before even trying to power this up ,i would like to mount the deflection amplifier board and power it and know i have deflection on one set of plates feel saver to add the supplies to the CRT . next week some more the holidays some times get in the way well this time around .
Attachments
DSCN7342.JPG
The electromagnetic spectrum has no theoretical limit at either end. If all the mass/energy in the Universe is considered a 'limit', then that would be the only real theoretical limit to the maximum frequency attainable.
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Harry Dalek
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Re: The Beast

Postby Harry Dalek » Fri Apr 09, 2021 8:07 pm

Now up to deflection side and that works really safer to have that before the powering the cathode ray tube .
Most of the HV supplies are there i will see if i can get them closer to what's need here before trying to fire up the CRT , that's my job tomorrow.
Attachments
DSCN7343.JPG
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The electromagnetic spectrum has no theoretical limit at either end. If all the mass/energy in the Universe is considered a 'limit', then that would be the only real theoretical limit to the maximum frequency attainable.
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Harry Dalek
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Re: The Beast

Postby Harry Dalek » Fri Apr 16, 2021 8:20 pm

Little step forward today i can see cathode rays very defocused but better than none ,the camera does make the result look brighter than to the eye and looks like i have no deflection which i do .
So a lot of work still to carry out on this one but i think getting to this point is a big step and its now working out getting the voltages closer to what the tube needs .
Attachments
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The electromagnetic spectrum has no theoretical limit at either end. If all the mass/energy in the Universe is considered a 'limit', then that would be the only real theoretical limit to the maximum frequency attainable.
User avatar
Harry Dalek
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Re: The Beast

Postby Harry Dalek » Sat Apr 17, 2021 9:24 pm

Testing today i could see it will need some changes to go further .
What i found bit hard to understand is the difference in the Data sheet to what the data in the Scope circuit is showing me .
Shown in screen grabs ..................................................................................................................
Anode 1 scope 250v + Anode Date sheet normal operating 1.2KV ! that is a bit of difference .
Anode 3 Angain 250v Anode 3 data sheet 1.2 kv again mmmm
IPS....the scope circuit must be under 300 with that pot but again data shows it should be 1.2Kv on the IPS pin
scope beam blanking data 800 to 1kv at the moment 250v
Registration the same 800 to 1Kv same one 250 at the moment
Focus in the scope circuit -500v data i can't tell top range is 1.5KV ,i am running at -800
If i am right reading the data i need a higher positive supply on the high end 1.2KV positive .
I have the 1.2kv negative supply and low hundreds positive supply and adding a 1.2 KV positive supply seem a path to go
It sort of makes sense why the spot on the screen even with deflection is not very controllable really just a smudge of a spot .
Not an easy tube to control but it needs what it needs and i haven't giving it that yet its only confusing with 2 sets of data showing different needs
BTW i took of the Green filter the Tube does have a green phosphor...so its on the lower range in the data sheet i would say .
Attachments
Screen 00002.jpg
Screen 00002.jpg (21.18 KiB) Viewed 302 times
Screen 00004.jpg
Screen 00004.jpg (24.16 KiB) Viewed 302 times
Screen 00003.jpg
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The electromagnetic spectrum has no theoretical limit at either end. If all the mass/energy in the Universe is considered a 'limit', then that would be the only real theoretical limit to the maximum frequency attainable.
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Harry Dalek
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Re: The Beast

Postby Steve Anderson » Sun Apr 18, 2021 11:53 am

I'm surprised you're getting anything on the screen at such low voltages, but at least you know there's some life in the tube. I would sit down and re-think the power arrangements. CRTs of this type ('scope tubes) are amazingly flexible, but as they become more specialised (this one) they do tend to be more 'fussy' with how they're fed and nurtured.

Steve A.
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Re: The Beast

Postby Harry Dalek » Sun Apr 18, 2021 2:51 pm

Steve Anderson wrote:I'm surprised you're getting anything on the screen at such low voltages, but at least you know there's some life in the tube. I would sit down and re-think the power arrangements. CRTs of this type ('scope tubes) are amazingly flexible, but as they become more specialised (this one) they do tend to be more 'fussy' with how they're fed and nurtured.

Steve A.


Hi Steve
I know this ones a hard one but that makes it fun don't what things to be to easy ! :wink:
And i will sure learn a lot which i have already just getting a smudgy spot on the screen is an accomplishment .
I am doing this so far just using your 3Bp1 CRT circuit and also the deflection amplifiers just in case i get focus so i don't damage the tube. controlling the beam cut off is close to the 3bp1 so that works so far as is .

The EHT is up around the high 3Kv i am making that with a fly back transformer i can adjust it and could go higher its on 12 volts to get that but circuit can run on 40 volts but its giving what the data says so left it as is ...dropping the supply which is variable result is like a light a brightness control dropping to 2Kv and below...i think i can run it on 4.5Kv which i have not tried yet .
Focus is on -800 does not seem to effect any thing much that i can see tube data or scope circuits says it should be around -500
Main supply i am using to the CRT circuit is -1.2Kv bit over what the scope circuit is using 1kV.
Yes i have Stopped to think about which way to go i have so far used the scope circuit as some thing to copy from as far as voltages ,the data seems different for typical operational voltage to the grids and anodes .
If i go that way i need a positive 1.2kv supply pretty easy to to do just a positive version negative supply ,pretty have every other voltage possible built already and adjust able .
Before i hooked every thing up i used a spare 3BP1 just to test the circuit powering Circuit to the CRT worked and Ramp and deflection amplifiers worked all displayed well ...well on 1.2KV lower than wanted for a 3Bp1 so what was expected .
The electromagnetic spectrum has no theoretical limit at either end. If all the mass/energy in the Universe is considered a 'limit', then that would be the only real theoretical limit to the maximum frequency attainable.
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Harry Dalek
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Re: The Beast

Postby Harry Dalek » Sat Apr 24, 2021 10:01 am

I thought i would take a different take on how to work out what the Tube needs as in trying a resistor divider to first see if i could work out all this ,first removing the beam cut off so i purely can work with beam with out this effecting it (i want to see what i am doing ! ) .
The Tube is a H1025 there are a few versions of this CRT so data i have may be a touch off what this Tube needs.
I have focus but the last pot was a bit worn causing problems so just replaced quick with a 2 watt 4 meg resistor so a touch off range now for my focus pot .
Now i have a raster if sorts this helps a lot ,i expect to refine the resistor chain when i have time and take some more readings once i know all is correct .
From what i worked out so far very much closer to the Scope circuit more than the data sheet need to tweak voltages a touch better to make sure ,it seems beam cut off was way off what i was using removing this for now i can work on the once problem when i get back to it .
Little bit of success today The beast is being tamed !
Attachments
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DSCN7363.JPG
The electromagnetic spectrum has no theoretical limit at either end. If all the mass/energy in the Universe is considered a 'limit', then that would be the only real theoretical limit to the maximum frequency attainable.
User avatar
Harry Dalek
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Location: Australia

Re: The Beast

Postby Harry Dalek » Sun Apr 25, 2021 4:37 pm

Today i replaced the flyback EHT with a Cockcroft-Walton voltage multiplier first go here 2.5KV enough drive the CRT , the flyback was to noisy good for testing but not for this ,one of the things Steve has mentioned to me a few times so an easy fix when you listen :wink:
I also got the correct deflection plates now .....but for now ! i think i have to just use one of the X axis as i only have one set of these and here i am just using one electron gun so far i have 2 Y axis sets .
So a little cleaner today and another step to Making the beast work for me
Attachments
DSCN7379_x264.mp4
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DSCN7382.JPG
The electromagnetic spectrum has no theoretical limit at either end. If all the mass/energy in the Universe is considered a 'limit', then that would be the only real theoretical limit to the maximum frequency attainable.
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Harry Dalek
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Re: The Beast

Postby Steve Anderson » Sun Apr 25, 2021 5:04 pm

You know Harry, I have to admire your perseverance! I don't know if I would have attempted this, but here you are with a useable raster, actually a clear and sharp one. All I can say is "Well done!"

Steve A.
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Re: The Beast

Postby Harry Dalek » Sun Apr 25, 2021 8:02 pm

Steve Anderson wrote:You know Harry, I have to admire your perseverance! I don't know if I would have attempted this, but here you are with a useable raster, actually a clear and sharp one. All I can say is "Well done!"

Steve A.


Thanks Steve ! i was thinking i should know enough by now to light it up try and tweak any results pretty much where i am at the moment .
Very happy with results today ,nice raster does show the CRT is useable so that means i can use it for what i hoped to use it for .
Its largest electrostatically graticule free CRT i have handy ,not an easy to tube to work out at first site but when you have a little bit of data as you helped me does make it possible gone a bit quicker than i expected .
I need to clean the experimental wiring mess up and Tweak parts to the gun and copy it for the second gun .
Not sure how it will go but the plan is video for one gun and second gun for a scope a one tube Binocular project idea .
Thanks again Steve i took this on using what you pretty much taught me so if i can do it you can .
The electromagnetic spectrum has no theoretical limit at either end. If all the mass/energy in the Universe is considered a 'limit', then that would be the only real theoretical limit to the maximum frequency attainable.
User avatar
Harry Dalek
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Posts: 4605
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Re: The Beast

Postby Harry Dalek » Sun Apr 25, 2021 9:32 pm

This is project CRT is a H1025 ,i came across this GEC H1046 when looking for extra data Tube pretty much looks the same as mine but it is different , has either a white or blue phosphor looks similar to most P7 SSTV crts using a filter of this colour, my filter is Green as is the Phosphor.
Mu metal shield on mine is similar but all one unit not split like this one .
Runs a bit higher than mine at 4kV data is in PDF a few posts back
Attachments
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s-l1600 (8).jpg
s-l1600 (2).jpg
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The electromagnetic spectrum has no theoretical limit at either end. If all the mass/energy in the Universe is considered a 'limit', then that would be the only real theoretical limit to the maximum frequency attainable.
User avatar
Harry Dalek
"Fester! Don't do that to 'Thing'"
 
Posts: 4605
Joined: Fri Sep 26, 2008 4:58 pm
Location: Australia

Re: The Beast

Postby Harry Dalek » Fri Apr 30, 2021 8:56 pm

What i did today was increase the output of the EHT to 3 KV added some higher filtering capacitors for a cleaner DC Output taking 7 450v 10uf's in series and 7 10meg resistors across those to discharge the cap's on switch off that works well .

I also swapped back over to Steves CRT 3BP1 circuit since its built to try this experimental CRT tube ,focus great works fine ,i am having trouble with the beam cut off only seems to be getting 10 volts across cathode to control grid when the opto coupler led is fully on i need about -54 volts here , my zener is 72 volts which should be more than enough for total beam cut off but not getting that control 44 volts off whats needed ,this zener in measuring fine across it so it must be working , swapped the optocoupler so its not that ,measuring 5 volts across the 5 volt zener ,could be the PNP HV Transistor i haven't looked at that yet ,The diode seems to measure its ok .
So spending a bit of time here working this out ,i have 2 identical CRT circuits for both CRT guns ,i will swap over and see if i get the same results or not tomorrow but will do a bit more measuring and jot down the numbers to compare to the other circuit ,i have a feeling its the transistor ZTX558 , only 5 things it could be on the solid state parts...mystery so far and only gets fixed checking checking and more checking : )
Once this is fixed i will move on to the video circuits which i will use what i learnt from the Devil monitor
Attachments
24a.gif
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The electromagnetic spectrum has no theoretical limit at either end. If all the mass/energy in the Universe is considered a 'limit', then that would be the only real theoretical limit to the maximum frequency attainable.
User avatar
Harry Dalek
"Fester! Don't do that to 'Thing'"
 
Posts: 4605
Joined: Fri Sep 26, 2008 4:58 pm
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