Date   

Re: Bringing up to snuff a Tek 465M

 

On 16 Feb 2016 13:45:13 -0800, you wrote:

Does anyone know if the "bleed" on the screen is normal for a CRT screen like the one on the
465M? Here's a video of mine as I turn up the intensity:
Yes, it is perfectly normal. It is partly caused by normal scattering, partly (mostly the halo-like disc) by the scan expansion mesh that these CRT's use to increase the horizontal and vertical deviation sensitivity (and possibly reduce the deviation sensitivity to PDA acceleration voltage).
You'll find that intensity is fully satisfactory in almost all cases long before this effect becomes disturbing. Standard good practice is to not increase intensity beyond a level that permits good visibility, for a number of reasons.

Raymond
It looks normal to me.

I think the ghosting directly surrounding the bright parts of the
trace is secondary emission from the electrons hitting the screen; the
high anode voltage from the PDA (post deflection acceleration) pulls
them back where they strike the phosphor surrounding the current beam
position. All oscilloscopes with PDA display this behavior.

The scan expansion mesh creates a ghost which is *not* aligned with
the beam (except in the very center) and is not normally visible. If
you want to see it, remove the input signal and use a slow sweep so
that you can watch the beam progress across the screen. The ghost
from the scan expansion mesh will follow the beam position catching up
at the center of the screen and then precede the beam to the right.


Re: Probes for 2445A

 

That is about the same price as a new Chinese made Texas probe which
would also work. Texas is either the OEM for the current crop of
Keysight oscilloscope probes (and Rigol and probably others) or they
are both made by the same company.

<http://www.ebay.com/itm/Two-new-250MHZ-Oscilloscope-clip-probes-w-readout-pin-/220306079644>

If you buy those, then you get all the little probe tip accessories as
well. They have two high frequency adjustments on the compensation
box so they can be adapted to different oscilloscopes although I did
not have to adjust mine for use below 200 MHz.

On Tue, 16 Feb 2016 18:56:17 +0000, you wrote:

Hi,

Before I spend $200 on 4 P6133 probes (ebay #351442258034) shipped to the
UK, am I getting the correct ones for my Tek 2445A? Is that a good price?

Thanks,
Malcolm


Re: 7904 - Very Dim Trace

 

Thanks to David DiGiacomo for correcting me on this. I did not even
notice that the DC restorers are on a separate board from the z-axis
amplifier. I have not had my 7904 apart that far.

The z-axis board includes the amplifiers and adjustments including the
grid bias control. I think you could get by with just making
measurements to verify proper operation but changing it should do no
harm and looks to be the easiest thing to do.

On 16 Feb 2016 06:39:38 -0800, you wrote:

Right. So far, I've not torn into the HV sections of the power supply. Replacing/Fixing the Z-axis board is on the path of least resistance...
On Mon, 15 Feb 2016 22:56:40 -0700, you wrote:

On Mon, Feb 15, 2016 at 10:31 PM, David <@DWH> wrote:

agree that your proposed steps are the way to go. The z-axis DC
restorer is the most likely suspect so replace or rebuild the z-axis
board
Except the DC restorer is in the high voltage module, not on the Z-axis board...


Re: Bringing up to snuff a Tek 465M

 

Does anyone know if the "bleed" on the screen is normal for a CRT screen like the one on the
465M? Here's a video of mine as I turn up the intensity:
Yes, it is perfectly normal. It is partly caused by normal scattering, partly (mostly the halo-like disc) by the scan expansion mesh that these CRT's use to increase the horizontal and vertical deviation sensitivity (and possibly reduce the deviation sensitivity to PDA acceleration voltage).
You'll find that intensity is fully satisfactory in almost all cases long before this effect becomes disturbing. Standard good practice is to not increase intensity beyond a level that permits good visibility, for a number of reasons.

Raymond


Re: Bringing up to snuff a Tek 465M

eliya gwetta
 

Does anyone know if the "bleed" on the screen is normal for a CRT screen like the one on the 465M? Here's a video of mine as I turn up the intensity:

https://youtu.be/0qielKd25RE https://youtu.be/0qielKd25RE


Re: Probes for 2445A

 

it's a 2 metre.
>
Yeah, I had seen that and I'm not sure if it could be accomodated in a 1.3m without component change. These probes have several adjustments "under the hood", for those with the right equipment.

Re Probe suitability:

Googling "Tektronix P6131" shows a link to a useful pdf at Tek.com. In my Google results, it's at #2.

Raymond


Re: Probes for 2445A

Malcolm Hunter
 

On 16 February 2016 at 20:23, @Raymond [TekScopes] <
TekScopes@...> wrote:

I confirmed to the seller that I would like to buy them if they are good
(cable etc.)
The seller is on this Marktplaats for 6.5 years, which usually means that
they are ok. He's got some other "serious/professional" stuff for sale ATM
as well.
I'll let you know as soon as I get a response.

​Thanks Raymond​

You know there are several versions of these probes? Firstly, there are
different cable lengths: These are all "nice and short" 1.3m length, i.e.
highest BW. Also, there's an Option 25 (I think), which has the larger,
more traditional (6 mm) tip. AFAI could see, these are not Option 25.

​I thought that was the P6133 with the Option 25?



Should you want to (start with) a spare cable: There's one for sale "brand
new" from Israel on Ebay # 231844909513.
​Tempting. I might get that if I have a P6131 complete - it's a 2 metre.

Malcolm​


[Non-text portions of this message have been removed]


Re: Probes for 2445A

Malcolm Hunter
 

On 16 February 2016 at 20:12, John Clark johnclark05@...
[TekScopes] <TekScopes@...> wrote:

I found the old Tek catalogs very helpful for this. The latest catalog
available on the TekWiki site is from 2000 but on page 500 it lists the
suggested replacement probes for the discontinued instruments, including
the 2445A.

<http://w140.com/tekwiki/wiki/Tek_Catalogs>
​Thanks. These seem to be quite specific and don't mention that you can use
a P6131 on a 2445A (for example).

Malcolm​


Re: Probes for 2445A

 

Malcolm,
I confirmed to the seller that I would like to buy them if they are good (cable etc.)
The seller is on this Marktplaats for 6.5 years, which usually means that they are ok. He's got some other "serious/professional" stuff for sale ATM as well.
I'll let you know as soon as I get a response.

You know there are several versions of these probes? Firstly, there are different cable lengths: These are all "nice and short" 1.3m length, i.e. highest BW. Also, there's an Option 25 (I think), which has the larger, more traditional (6 mm) tip. AFAI could see, these are not Option 25.

Should you want to (start with) a spare cable: There's one for sale "brand new" from Israel on Ebay # 231844909513.

Raymond


Re: Probes for 2445A

John Clark
 

Malcom,
I found the old Tek catalogs very helpful for this. The latest catalog available on the TekWiki site is from 2000 but on page 500 it lists the suggested replacement probes for the discontinued instruments, including the 2445A.

<http://w140.com/tekwiki/wiki/Tek_Catalogs>

John

To: TekScopes@...
From: TekScopes@...
Date: Tue, 16 Feb 2016 18:56:17 +0000
Subject: [TekScopes] Probes for 2445A


























Hi,



Before I spend $200 on 4 P6133 probes (ebay #351442258034) shipped to the

UK, am I getting the correct ones for my Tek 2445A? Is that a good price?



Thanks,

Malcolm



[Non-text portions of this message have been removed]


Re: Probes for 2445A

Malcolm Hunter
 

On 16 February 2016 at 19:16, 'Colin Herbert' colingherbert@...
[TekScopes] <TekScopes@...> wrote:

Yes, I think so. In future, you could always take a peek here:

http://www.barrytech.com/tektronix/probes/tekprobes.html

You'll find a wealth of info on Tek probes, including compatibility,
original prices, eBay prices, etc..
​Thanks Colin. Yes, I knew about that list but​ didn't want to risk $200 on
my interpretation.

Malcolm


[Non-text portions of this message have been removed]


Re: Probes for 2445A

 

Made a mistake in my recent msg.Here is a link (in Dutch . Please Yahoo, don't let me down on this:

<http://www.marktplaats.nl/a/doe-het-zelf-en-verbouw/meetapparatuur/m1020754709-tektronix-p6131-probes.html?c=8c285449651fa109c354bbabe740c1b&previousPage=lr>

Raymond


Re: Probes for 2445A

 

Hi Malcolm,
I don't think that's a very good price at all.
P6133's are regularly available in (continental) Europe at lower prices. The other day, four P6131's (300 MHz, well suited for anything from 2445(X) to 2465/67(X)) € 25 each, which is typical. Two are left at the moment.
P6138/39's etc. are more expensive - and not as easily adapted to a 24XX.
Like the probes in your link, the low-inductance accessory "pins" don't seem to be part of the deal though.
I'll buy them for you if you want. I would try and get confirmation that cables are in perfect condition.
P6106(A)'s (as an example) are well suited for your 2445(X) as well and not expensive.

Raymond


Re: Probes for 2445A

Colin Herbert
 

Yes, I think so. In future, you could always take a peek here:



http://www.barrytech.com/tektronix/probes/tekprobes.html



You'll find a wealth of info on Tek probes, including compatibility,
original prices, eBay prices, etc..



Colin



From: TekScopes@... [mailto:TekScopes@...]
Sent: 16 February 2016 18:56
To: TekScopes@...
Subject: [TekScopes] Probes for 2445A





Hi,

Before I spend $200 on 4 P6133 probes (ebay #351442258034) shipped to the
UK, am I getting the correct ones for my Tek 2445A? Is that a good price?

Thanks,
Malcolm


Re: Ebay Rip-off ? - "Global Shipping Program"

tek_547
 

Also a bit late Dennis but good to know, thanx!
René


Probes for 2445A

Malcolm Hunter
 

Hi,

Before I spend $200 on 4 P6133 probes (ebay #351442258034) shipped to the
UK, am I getting the correct ones for my Tek 2445A? Is that a good price?

Thanks,
Malcolm


Re: Tek 465 intensity problem

Tom Gardner
 

On 16/02/16 00:15, fqo63ta@... [TekScopes] wrote:

The 0777 CRT will run just fine in a 465...I've done it many times.
This raises the question of how to determine which tubes can work in which scopes, especially tubes (such at the 0777) that weren't originally used in the (465) scope. My only sources are:
http://www.reprise.com/host/tektronix/reference/crt.asp
and
http://www.sphere.bc.ca/test/tek-crts.html

Are there any others?


Re: CRT article

EB4APL
 

Neutral gray filters are the most basic, the principle of operation is
that the light from the phosphor crosses the filter one time but the
ambient light does twice, one time to the screen and other when
reflected back so it is attenuated twice that the light from the trace.
Colored filters usually are made in a color that matches the emission
spectra of the phosphor so the trace light is attenuated much less than
the ambient light.
The metallic mesh filters also serve another purpose, they shield the
EMI leaking from the screen aperture.
There are more sophisticated filters like the polarized ones that are
based in that the reflected light is polarized in reverse so it is
attenuated very much. They work like Polaroid sunglasses.

Regards,
Ignacio

El 16/02/2016 a las 16:56, 'Dale H. Cook'
bridgewaterma@... [TekScopes] escribi:

At 10:12 AM 2/16/2016, Dwayne Verhey wrote:

I was also intrigued by the notation that most scopes came with a
grey filter. In my very limited experience, I have not seen one remain
with the scope over the years, or tried one. How effective are they?

They can be very effective when there is a lot of ambient light that
would otherwise reflect off of the face of the CRT or affect the
phosphor. Gray filters made of a fine mesh have also been used for
that purpose, as on my 453:

http://plymouthcolony.net/starcity/radios/images/tek453_a.jpg

Dale H. Cook, GR / HP Collector, Roanoke/Lynchburg, VA
http://plymouthcolony.net/starcity/radios/index.html


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Posted by: "Dale H. Cook" <bridgewaterma@...>
------------------------------------------------------------------------


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Re: CRT article

Dale H. Cook
 

At 10:12 AM 2/16/2016, Dwayne Verhey wrote:

I was also intrigued by the notation that most scopes came with a grey filter. In my very limited experience, I have not seen one remain with the scope over the years, or tried one. How effective are they?
They can be very effective when there is a lot of ambient light that would otherwise reflect off of the face of the CRT or affect the phosphor. Gray filters made of a fine mesh have also been used for that purpose, as on my 453:

http://plymouthcolony.net/starcity/radios/images/tek453_a.jpg

Dale H. Cook, GR / HP Collector, Roanoke/Lynchburg, VA
http://plymouthcolony.net/starcity/radios/index.html


Re: CRT article

Marian B
 

On 16.02.2016 16:12, Dwayne Verhey tekscopes@... [TekScopes] wrote:
On 15/02/2016 4:35 PM, David @DWH [TekScopes] wrote:

http://www.davmar.org/concepts.html
http://www.davmar.org/TE/TekConcepts/062-0852-01_CRTs_Jul69.pdf
That was a great read, and really helped clear up some concepts for me
(eg: what exactly does the astigmatism control adjust?).
Indeed a good read! I feel like I should learn more about electron
optics, can someone recommend a book about them?

Cheers, Marian