The Medium band Television Monitor

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Re: The Medium band Television Monitor

Postby Harry Dalek » Sun May 07, 2023 12:35 pm

Post up readings this afternoon when i get home
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 Medium band Television Monitor

Postby Harry Dalek » Sun May 07, 2023 5:50 pm

Thought it would be easier to add the readings to the schematic .
Part changes shown just some resistors to get focus better .


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I took note of the readings as to where i took ground and the cathode readings from they seem a bit odd to me as the positive and negative voltages seem reversed to the other Crts

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Now what i found my multiplier under load gives 1.6Kv i have( 2 2W 220k in parallel) which drops that voltage to 1.280V why ? i must not have checked underload the voltage after the resistors ,seeing that now i could increase that voltage 200v 300v more so at least a touch under 1.6Kv .

I will start another post as i have 2 videos to show and get this one out of the way
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 Medium band Television Monitor

Postby Harry Dalek » Sun May 07, 2023 6:28 pm

Problem or slight problem with Brightness control when setting is adjusted close to beam cut off
Below with the original 470K 2W resistor after the focus pot to ground very defocused but you can see towards the end at beam cut off it gets a bit messy and beam moves to the right


The Problem adjusting brightness shows up more when the beam has better focus



On something else my son got a laser temperature gun i thought this will come in handy checking the resistors or any thing else over heating and will keep my fingers away from nasty voltages .
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All the caps and diodes nice and cool and most of the resistors but the one i am worried about is the 2W 100k across the focus pot its showing 153 C but pretty steady i have this one mounted high above the PCB .
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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 Medium band Television Monitor

Postby Steve Anderson » Sun May 07, 2023 7:22 pm

It seems Harry that you're not far off the mark on voltages for this CRT. It wouldn't be a problem to re-do that drawing specifically for the 150BT-B31, just a simple bit of number-crunching on the calculator and altering the text within the drawing. From what you've hinted at it may be that the power supply for the CRT circuit is a bit 'weak', the voltage 'sags' under a varying load. But one thing at a time...I'll get to it in the morning...I would do it now, but it's 40 Celcius in my office/workshop...time to shut down the PC...

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Re: The Medium band Television Monitor

Postby Harry Dalek » Sun May 07, 2023 9:15 pm

Steve Anderson wrote:It seems Harry that you're not far off the mark on voltages for this CRT. It wouldn't be a problem to re-do that drawing specifically for the 150BT-B31, just a simple bit of number-crunching on the calculator and altering the text within the drawing. From what you've hinted at it may be that the power supply for the CRT circuit is a bit 'weak', the voltage 'sags' under a varying load. But one thing at a time...I'll get to it in the morning...I would do it now, but it's 40 Celcius in my office/workshop...time to shut down the PC...

Steve A.


OH thanks Steve yes that would be good to see what you think of the voltages and a neater drawing i forgot to take the reading before the 220K i was going to take it now but have a guest sleeping in the room where my work table is i have to take it tomorrow

I would move on but seems a bit more work getting the CRT's voltages nicer i didn't realise under load i dropped the HV negative so much an easy fix i suppose, but increasing this voltage current i would expect a bit more heating at the focus pot 100k resistor so the 69K i am using after the focus pot that was 470k might have to be adjusted back to that to be safe till we find out what it should be i can do it trial and error seeing which way to adjust the resistor values but your maths skills would be appreciated.
Reason i think that one is heating and not the 69K is i have 3 2 watt resistors in parallel to drop the 470K to 69K spreading the heating i think .
Any case an increase in the high negative seems correct a normal working voltage of 2Kv i thought i was pushing it dropping it 700v or 800v makes sense now on the defocused beam is neater to cut out than a higher focused beam with a lower HV negative .
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 Medium band Television Monitor

Postby Harry Dalek » Mon May 08, 2023 7:28 am

update i think my meter was low battery Steve double checking this morning i was getting different readings and checked with the other meter and its now showing same on both meters after a battery change arrrr rookie mistake ! :oops:
New readings look more normal multiplier out -1790 v after the 2 220k in parallel (Dropped voltage to stop sparking ) its -1569v to the CRT circuit -
before the 220k its -1500v after the 220k top of the focus pot its -1068 +427 after focus pot -875 +400 and to astig +369v
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 Medium band Television Monitor

Postby Steve Anderson » Mon May 08, 2023 10:52 am

Yes, we all get caught out by the low battery on a multimeter situation at some point. Often the symbol on the display for low battery is too small to notice...then only to find you don't have a replacement battery in the house...a quick trip to the 711 is next...thankfully they're open 24hrs! If you're in a small village or really rural, you'll have to wait until the next time you go into town...luckily my nearest 711 is only 400m away...a couple of minutes on my old trusty 1980 edition bicycle...problem sorted...and a bit of exercise at the same time...though a downer when there's heavy rain, it is coming up to the wet season here...

Steve A.
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Re: The Medium band Television Monitor

Postby Steve Anderson » Mon May 08, 2023 2:38 pm

I now see part of the problem you've had with this CRT...the information for it is all over the place! Mostly to do with conflicting pin numbers. This may take a while longer than I thought...if it can be fathomed out at all...

Steve A.
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Re: The Medium band Television Monitor

Postby Harry Dalek » Mon May 08, 2023 5:44 pm

Steve Anderson wrote:Yes, we all get caught out by the low battery on a multimeter situation at some point. Often the symbol on the display for low battery is too small to notice...then only to find you don't have a replacement battery in the house...a quick trip to the 711 is next...thankfully they're open 24hrs! If you're in a small village or really rural, you'll have to wait until the next time you go into town...luckily my nearest 711 is only 400m away...a couple of minutes on my old trusty 1980 edition bicycle...problem sorted...and a bit of exercise at the same time...though a downer when there's heavy rain, it is coming up to the wet season here...

Steve A.


Yes i got caught out for sure ! The double checking this morning before work pointed right to the Battery being weak .Lucky i had time to check all the readings again .
Only thing took the readings shown with the 470K from focus pot to ground instead of the 69K which has the beam better focused than defocused i would think the readings would be a touch different with the better focused Resistor in place .
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 Medium band Television Monitor

Postby Harry Dalek » Mon May 08, 2023 6:07 pm

Steve Anderson wrote:I now see part of the problem you've had with this CRT...the information for it is all over the place! Mostly to do with conflicting pin numbers. This may take a while longer than I thought...if it can be fathomed out at all...

Steve A.


Yes that was my first problem same CRT with different pinout i think i have it right it sort of has a mu metal shield which is hard to take off so could not double check the pinout by looking at what go's where.
The most confusing CRT i have ever come across yet Well you can see what went with cathode pin 3 not 7 the deflection plates match what i am seeing as well and the N/C pins match the socket .
Just the Astig think pins 5 and 6 i have tied together i am not sure if that's correct i have seen one scope schematic that does this for this CRT and its done inside other CRTS but must be a reason why there's separate pins ,what it seems to do when i adjust the high positive Astig control it increases the trace line size or lowers it a bit .
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 Medium band Television Monitor

Postby Harry Dalek » Fri May 19, 2023 2:57 pm

Sorry for the lack of time on the project ,today needed a big bench clean up running out of room and looking very messy ,not a good thing with working on the High voltages !
That's cleaned up now and looked back into the temperature of the 100k resistor across the focus pot only thing a little hot for me liking so swapped over what i think is a 5 Watt 120K i had handy ,the case of the resistor is now about half of what it was finding the Resistor wirer that enters the casing is up around the high 80's C but its case is staying around 30 C not sure if left for hours if the temperature would climb the resistor is mounted high off the board so i would think its safe enough seems stable ,i find if things are going to over heat you get that result pretty quick .
I am thinking of using the metal case as a heatsink its on my mind or perhaps using some lower resistance in series but a few watts for each Resistor .
So apart for this minor fussy fixation i have on its Temperature every thing else is well behaved .
I am still not 100% sure why the sinewave on the deflection plates looses its position on beam cut off but a guess might be the 24 volts AC might be to low to control when the beam intensity is lowered .
So i will just move on to getting the Ramp generation circuits up and running in this and see what happens .

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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 Medium band Television Monitor

Postby Harry Dalek » Sun May 21, 2023 9:39 am

Been working on mounting the boards the NBTV side is sort of done with Steve's analogue digital converter i had a spare i made some time back ,i say sort of as its not wired in yet and on this type of circuit i have never tried to sync it to the video signal just used a crystal clock ,but any case it will come in handy testing the deflection amplifier result on this CRT which i want to do next .
I have 2 spare boards i might make an analogue version on the now slightly higher line rates which the A/D converter i suppose could do as well with 2 variable clocks feeding the H/V sides so i will see how it go's.
Syncing is easier on the analogue version but i will try it on this already made circuit and may be i will not need the extra boards apart from the clock circuits .
I will see how it go's later this i will have time to power the circuit up and test .
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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Harry Dalek
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Re: The Medium band Television Monitor

Postby Steve Anderson » Mon May 22, 2023 2:20 pm

Harry, just a quick note...I've sent you a PM...

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Re: The Medium band Television Monitor

Postby Harry Dalek » Thu May 25, 2023 4:18 pm

OK sitting down at my desk looking at a all that space in my project case i thought how good it would be if i could make use of it and add a scope as i did on the Binocular project .
I have still a few 3BP1's thanks to Andrew and as always a way to thank him is to use them ! well i have now done just that i don't muck around when i make my mind up its now mounted
As i found last time around doing this was not to hard at all a lot of circuit voltage sharing between the CRTs .
The idea is evolving again a better use of all the space .

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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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Posts: 5364
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Re: The Medium band Television Monitor

Postby Harry Dalek » Sat May 27, 2023 6:41 pm

Today built the 3BP1 CRT drive circuit i could of went with just a resistor chain for the original idea to power it for a scope but this can do both that and modulate it ,could very well do a scope and a second display depending on if i am willing to do it so i put in the Option .
I have the drive circuit above other side of the 150BT-B31 HV case keeping all this HV around the same area of the case .
Next week i will hook the 3BP1 to it and again try a raster line with the AC supply on the deflection plates see how the crt's go working together .
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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'"
 
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