Date   

Re: CRT book by Keller

Chuck Harris <cfharris@...>
 

Originally, the cathode ray tube, was a device to project
"cathode rays" at a phosphor screen... possibly with some
object (Maltese Cross) in between.

As I understand the description of the Coketron, it has something
like one of the ubiquitous 5UP1 gun assemblies in the neck, and
no internal deflection plates.

So, you should be able to focus the beam, and with a magnet do
experiments with magnetic deflection of said beam.

-Chuck Harris

Jeff Dutky wrote:

Tom,

I actually have the same question as Roy.

There are "CRTs" that merely illuminate the entire face of the tube, and others that have some limited amount of control over the illumination (e.g. the 6E5 tuning eye, or DM160 "Magic-Eye" indicator tubes). It is not clear from the description that the "coketron" was able to scan the beam, or whether it merely caused the end of the tube to illuminate like these Russian ILD3-K tubes (https://www.ebay.com/itm/ILD3-K-P590-ULTRARARE-VINTAGE-CRT-VFD-INDICATOR-TUBE-for-DIY-and-education/112031678404).

My copy of Peter Keller's book has not arrived, so I am speaking from a certain depth of ignorance.

-- Jeff Dutky






Re: Tektronix 492BP

 

I think option 8 remove the extended frequency. This unit may had that as the options tag has been erased as it is old probably 90s.


Re: 2465B trace and readout focus at different positions of focus knob

Chuck Harris <cfharris@...>
 

Yes, that is where the compromise that makes both
focus at about the same point happens.

Unfortunately, it is a compromise adjustment. The
readout is considered the designated loser in this
race.

-Chuck Harris

Mark Hatch wrote:

Hi,

Have a late model 2465B. Noticed today that the focus point for the readout is at one point on the focus knob. But it I also want to get an optimal focus for the trace, I need to turn the knob to a different position.

I guessing that I should first perform the 2465B CRT Adjustments (Grid Bias, High Drive Focus, and Edge Focus). Is this the right path here?

Focus knob is more or less in the center position when Readout is in focus and only a little off center with trace in focus.

Thanks

Mark






Re: Tektronix 492BP

 

May have been unit has been opened before, but works fine up to 21GHz. But what switches do you refer to on what board? Where can I find where the switches suppose to be?


Who has not received their book in the US by now?

 

If you have NOT received Peter Keller's book by now please contact me
off-list at dennis at ridesoft dot com and I will see if I can locate it for
you. Include your zip code in your email.

If you DID NOT receive Peter's book in the mail by TUESDAY EVENING please
let me know and include your zip code in the email.

Dennis Tillman W7pF


Re: CRT book by Keller

 

Tom,

I actually have the same question as Roy.

There are "CRTs" that merely illuminate the entire face of the tube, and others that have some limited amount of control over the illumination (e.g. the 6E5 tuning eye, or DM160 "Magic-Eye" indicator tubes). It is not clear from the description that the "coketron" was able to scan the beam, or whether it merely caused the end of the tube to illuminate like these Russian ILD3-K tubes (https://www.ebay.com/itm/ILD3-K-P590-ULTRARARE-VINTAGE-CRT-VFD-INDICATOR-TUBE-for-DIY-and-education/112031678404).

My copy of Peter Keller's book has not arrived, so I am speaking from a certain depth of ignorance.

-- Jeff Dutky


Re: Tektronix 492BP

Thomas S. Knutsen
 

You want to check those dip switches again, the alternative may be that the
EPROM is losing its memory, and that's not a fault you want to have.
Could it be that the switches have been fooled with by a former owner?

BR.
Thomas.


tor. 14. jan. 2021 kl. 21:56 skrev Mike Yepes <theamberco@hotmail.com>:

Thanks a lot for hte help but the dip switches on those boards are ok.
(Vertical digital storage and memory board)





--
With Best regards, Thomas S. Knutsen.

Please avoid sending me Word or PowerPoint attachments.


Re: Tektronix 492BP

 

Thanks a lot for hte help but the dip switches on those boards are ok. (Vertical digital storage and memory board)


Re: CRT book by Keller

Tom Lee
 

Your question baffles me, Roy. If someone were to hand you a non-Coke bottle crt, would you ask, "Yeah, but what does it do?"

It's a crt. Made out of a Coke bottle, yes, but a crt nonetheless.

Tom

--
Prof. Thomas H. Lee
Allen Ctr., Rm. 205
350 Jane Stanford Way
Stanford University
Stanford, CA 94305-4070
http://www-smirc.stanford.edu

On 1/14/2021 12:09, Roy Thistle wrote:
On Wed, Jan 13, 2021 at 05:49 PM, Glydeck wrote:

check it out
There is a bad photo of Peter's artifact... and as Peter claims... '... results in an operable CRT..." [pg. 24]
But given that it was "operable," what did it do?
Peter doesn't say?




Re: CRT book by Keller

Roy Thistle
 

On Wed, Jan 13, 2021 at 05:49 PM, Glydeck wrote:


check it out
There is a bad photo of Peter's artifact... and as Peter claims... '... results in an operable CRT..." [pg. 24]
But given that it was "operable," what did it do?
Peter doesn't say?


Re: Tektronix 492BP

Tom Lee
 

I've had the same experience as John, and not only with Tek's instruments. HP gear of that period also seems to suffer from the same affliction. That likely implies that you'd find this in the products of other manufacturers as well.

-- Tom

--
Prof. Thomas H. Lee
Allen Ctr., Rm. 205
350 Jane Stanford Way
Stanford University
Stanford, CA 94305-4070
http://www-smirc.stanford.edu

On 1/14/2021 11:27, John Miles wrote:
It's not a question of them being set incorrectly, it's a question of whether their contacts actually match their settings.

The DIP switches used by Tek in this era are extremely failure-prone due to aging. But normally they are OK until they're toggled on or off for the first time in 20+ years. You can rule out the switches by checking them with an ohmmeter to see if the ones that are in the 'OPEN' position are actually open (i.e., med/high resistance across the contacts.) Likewise for the others, with ~0 ohms expected across the contacts for the switches that are closed.

-- john, KE5FX


-----Original Message-----
From: TekScopes@groups.io [mailto:TekScopes@groups.io] On Behalf Of
Mike Yepes
Sent: Thursday, January 14, 2021 8:54 AM
To: TekScopes@groups.io
Subject: Re: [TekScopes] Tektronix 492BP

The only boards with dip switches are the memory board and the vertical
digital storage board. I have no idea which ones supposed to be on or off.






Re: Tektronix 492BP

John Miles
 

It's not a question of them being set incorrectly, it's a question of whether their contacts actually match their settings.

The DIP switches used by Tek in this era are extremely failure-prone due to aging. But normally they are OK until they're toggled on or off for the first time in 20+ years. You can rule out the switches by checking them with an ohmmeter to see if the ones that are in the 'OPEN' position are actually open (i.e., med/high resistance across the contacts.) Likewise for the others, with ~0 ohms expected across the contacts for the switches that are closed.

-- john, KE5FX

-----Original Message-----
From: TekScopes@groups.io [mailto:TekScopes@groups.io] On Behalf Of
Mike Yepes
Sent: Thursday, January 14, 2021 8:54 AM
To: TekScopes@groups.io
Subject: Re: [TekScopes] Tektronix 492BP

The only boards with dip switches are the memory board and the vertical
digital storage board. I have no idea which ones supposed to be on or off.



2465B trace and readout focus at different positions of focus knob

Mark Hatch
 

Hi,

Have a late model 2465B. Noticed today that the focus point for the readout is at one point on the focus knob. But it I also want to get an optimal focus for the trace, I need to turn the knob to a different position.

I guessing that I should first perform the 2465B CRT Adjustments (Grid Bias, High Drive Focus, and Edge Focus). Is this the right path here?

Focus knob is more or less in the center position when Readout is in focus and only a little off center with trace in focus.

Thanks

Mark


Re: Tektronix 492BP

Thomas S. Knutsen
 

That is the same as my 492BP.
If I remember it, I will take the cover off and note the switch settings. By flipping the switches you can get any model no. And any version. Often the switches fails after years and need replacement.

Thomas.

Sendt fra min iPhone

14. jan. 2021 kl. 19:05 skrev Mike Yepes <theamberco@hotmail.com>:

9.1 and 1.1 panel ver.





Re: Tektronix 492BP

 


Re: Tektronix 492BP

 

9.1 and 1.1 panel ver.


Re: 2247A Is this normal?

Alex
 

When that happens to me, I usually increase the screen intensity and then I can see that there was either some pulses or noise on the signal that go beyond the signal and are what actually are defining the position of the cursors, and where invisible under normal intensity conditions. Other than that I find the voltmeter function very accurate and useful.


Re: Tektronix 492BP

Thomas S. Knutsen
 

Start by giving what version no. Your SA gives when starting up. The dip
switches changes between the software versions.

If there is sockets on the front, and the correct cabling inside your SA
has external mixers. There was a different front panel for those without
it, and there is no pushbutton hole nor hole for IF in.
The only strange version is the 75ohm version that has some of the coaxes
inside re-routed and an 75ohm:50ohm transformer with BNC that goes into the
hole where IF input should have been.

BR.
Thomas.


tor. 14. jan. 2021 kl. 17:54 skrev Mike Yepes <theamberco@hotmail.com>:

The only boards with dip switches are the memory board and the vertical
digital storage board. I have no idea which ones supposed to be on or off.





--
With Best regards, Thomas S. Knutsen.

Please avoid sending me Word or PowerPoint attachments.


Re: Tektronix 492BP

 

The only boards with dip switches are the memory board and the vertical digital storage board. I have no idea which ones supposed to be on or off.


Re: Tektronix 492BP

 

Check the DIP switches in the CPU section for continuity, as well as the ones
on the Z-axis board. Sounds like one or more of them may have failed, and the
instrument thinks it doesn't have the external mixer jack.
I only have the operators manual. Let me see if I can find the schematics in pdf format somewhere.
I will revise that , thanks a lot.
So all units with the external mixer jacks must provide extended range? Becasue I was told there is an option that eliminted the extended range and this unit had erased the tag for the options so not sure if it may had that option.

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